From kenw8ek at gmail.com Tue Aug 9 11:49:03 2016 From: kenw8ek at gmail.com (Ken, W8EK) Date: Tue, 9 Aug 2016 11:49:03 -0400 Subject: [AMRadio] MFJ Items FS Message-ID: MFJ Items For Sale: Chrome CW Paddles, CW Pocket Reader, Coax Antenna Switches, DC Outlet Control Panel, Dual Digital Clock, Wall Wart Power Supplies, DC Bias T, and more . . Chrome CW Paddles: MFJ 564 Chrome CW Paddles Basically a clone of the Bencher BY-2 paddles. It has an extremely nice chrome base, with full range adjustment in tension and contact spacing, with self- adjusting nylon/steel needle bearings and non-skid feet and heavy base. This particular unit appears to be new. It is in its original box. $60 . . MFJ 461 Pocket CW Reader Automatic Speed Tracking MFJ AutoTrak automatically locks on and tracks CW speed to decode high and low speed Morse code. MFJ Instant Replay The most recent 140 characters can be instantly replayed. This lets you re-read or check your copy if you are copying along with the MFJ-461. High Performance Modem Consistently get solid copy from MFJs high performance PLL modem technology. Digs out weak signals and even tracks slightly drifting signals. Of course, nothing can clean up and copy a sloppy fist, especially with a weak signals with lots of QRM/QRN. High Contrast LCD Display 2-line LCD display has 32 large 1/4 inch high-contrast characters. You can display decoded CW as text and speed or switch to all text on both lines. True Pocket Size Fits in your shirt pocket with room to spare -- its smaller than a pack of cigarettes. Weighs less than 5.5 ounces. More Features A serial port lets you display CW text on a monitor using a computer and terminal program. When its too noisy for its microphone pickup, or when you don't want to hear CW you can connect the MFJ-461 to your receiver with a cable. Battery saving feature puts it to sleep during periods of inactivity. Uses 9-Volt battery. This one works fine, and looks close to new. $50 . . "Strip Line" Coaxial Antenna Switches: All of the following coax switches use "strip line" construction so that the 50 ohm impedance is closely preserved, making them usable at much higher frequencies. All work fine, look fine, and use SO-239 connectors. Paper work included with all. MFJ 1702 B, Two position "Strip Line" Coax Switch The unused terminal is automatically grounded, plus it has a third position grounding both antennas. Heavy cavity type construction. It looks great. $20 OPEK CX-201 2 position Coax Switch Unused port is grounded. VSWR: < 1.2:1 Center Ground Tap Impedance: 50-Ohms Power Rating: 1kW (cw) Frequency: Up to 600 MHz Insertion Loss: < 0.2 dB Isolation Loss: Better than 50dB Looks like new. $22 . . MFJ 1701, 6 position Coax Switch Rated for 1.8 to 30 MHz, 2000 W PEP, 1000 W CW. Unused terminals are grounded. This one has been used, but it is still in its original box. $45 . . MFJ 1118 DC Outlet Control Panel: The MFJ-1118 Multiple DC Power Outlet is a high current DC power outlet controller. It lets you power two HF and/or VHF transceivers and six or more accessories from your transceivers main 12 V DC supply. The MFJ-1118 has two pairs of super heavy duty 30 amp 5 way binding posts to connect your transceivers. Each pair is fused and RF bypassed. Handles 35 Amps total. Six pairs of heavy duty, RF bypassed 5-way binding posts let you power your accessories. They handle 15 Amps total, are protected by a master fuse and have an ON/OFF switch with "ON" LED indicator. The MFJ-1118 has a built-in 0-25 VDC voltage meter with six feet super heavy duty eight gauge cable. This one is new, in its original box, with paper work. MFJ sells these for $85. Get this one for only $60. . . MFJ 108 B, Dual digital clock: This clock has two LCD displays, each independent of the other. One is in 24 hour format, and ideal for setting to GMT. The other is in 12 hour format, ideal for setting to local time. It works fine and looks close to new. With single page manual for $18. . . Wall Cube Power Supplies: MFJ 1312 D, 12 V DC at 500 ma, $14 9 Volt DC at 500 ma This unit was used on a MFJ 422 keyer, but will also power other items needing 9 V DC. It has a 2.5 mm male plug on it, tip positive. $12 . . MFJ 4117 Bias T with DC switch: Used on many devices to send DC power down the RF Coax cable. Appears new. $25 . . I also have many other accessories available such as many different types of microphones, HTs, VHF and UHF rigs, HF and VHF/UHF antennas, connectors, miscellaneous accessories, etc. Just too many to list here. Please e-mail your requests. Prices do not include shipping from Florida. Thanks. 73, Ken, W8EK Ken Simpson E-mail to W8EK at FLHam.net or W8EK at arrl.net Voice Phone (352) 732-8400 From mjcal77 at yahoo.com Tue Aug 9 16:18:49 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Tue, 9 Aug 2016 20:18:49 +0000 (UTC) Subject: [AMRadio] Dayton References: <1065787302.14241289.1470773929438.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <1065787302.14241289.1470773929438.JavaMail.yahoo@mail.yahoo.com> >From a reply... "What made it great in my opinion was not that you'd find a Ranger or Matchbox or Weller soldering iron, but that you'd find weird or unusual items." If you know Ron WB4OQL, Carl, W4RCW, and the fellow I call the bug man because he works for Dow Chemical, N4TIC, Bill, and George, W4BUW who has a thing for SP600's like Mel Gibson had for the book 'Catcher in the Rye' in the Conspiracy Theory, you may have run across me selling at their booth for a few years several years ago. I agree, the rare and unique shows up at Dayton, but the one thing I noticed was comments on stuff, something you never heard years ago. Two fellows will be looking at things and asking each other what this is or what do think that was for as the go over the stuff on a table, and it will be common parts that the most neophyte Novice knew about in the day. Today, for many folks, it is like a walk though the caveman exhibit at a museum, wondering what all those things were used for. Another comment I always got a chuckle from, was a couple OT's would see something and one would say, I had one of those back in the...insert favorite year, and his partner would say why don't you buy it for nostalgia reasons. The best answer, "No, it was a piece of crap back then too, I'm sure it isn't any better now." I also learned to watch your stuff like a hawk. Somebody examining an HR10 I had for sale reached around and stole the crystals out of the filter. A few months later I was lucky enough to have a fellow give me two for a few 12BY7's. Charlie, W4MEC in NC From k4kyv at charter.net Wed Aug 10 16:26:38 2016 From: k4kyv at charter.net (Donald Chester) Date: Wed, 10 Aug 2016 15:26:38 -0500 Subject: [AMRadio] Dayton In-Reply-To: <1065787302.14241289.1470773929438.JavaMail.yahoo@mail.yahoo.com> References: <1065787302.14241289.1470773929438.JavaMail.yahoo.ref@mail.yahoo.com> <1065787302.14241289.1470773929438.JavaMail.yahoo@mail.yahoo.com> Message-ID: <000901d1f345$7f689b70$7e39d250$@charter.net> > "What made it great in my opinion was not that you'd find a Ranger or > Matchbox or Weller soldering iron, but that you'd find weird or unusual > items." > > Charlie, W4MEC in NC That's what I go for. No interest in DX-100s, NC300s, Viking Valiants, GK-500s, "ham radio quality" modulation transformers or "vintage SSB" junk. Just oddball unobtanium items I have been on lookout for years, that occasionally shows up, like EF Johnson coil clips, Bud metal name plates, plug-in coil hardware and other little esoteric stiff. This last time, I did pick up a 75A4. It was very clean and only $300, but didn't work and the guy said he couldn't figure out what was wrong with it. I got it running but it still needs work. If I can get it up to par I might use it for my main receiver. I might take home a quality piece of pre-WWII gear in reasonable condx, or a bargain priced broadcast modulation transformer or reactor, but most of the "goodies" I see now I already have, and need the room more than I need additional copies. Don k4kyv From mjcal77 at yahoo.com Fri Aug 12 10:00:35 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Fri, 12 Aug 2016 14:00:35 +0000 (UTC) Subject: [AMRadio] AM-864/U References: <429843097.15143018.1471010435915.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> Anybody familiar with this audio amp? Was used in studio applications to maintain a constant audio level output placed between studio equipment and the TX and is apparently still highly sought after when you see what they want for it on ebay. I have owned one for over 45 years, getting it in a govt. surplus sale in 1971 at NAS JAX, and have used it on an off for different things, but now want to use it in earnest in a homebrew TX project. Dragged it out and went through it, replacing all the coupling caps as they were all leaking, and performed the alignment procedures. Putting in -35db (.066 volts) at 1Khz, it is only supposed to deliver 0 DB into 600 ohms, and mine gives +10 into a lab audio power meter set to 600 ohms. It functions exactly buy the book in its regulation function maintaining 0 out over a 10db input swing. The only thing I found was the plate resistors on the input push pull amp tube were 12K, while the schematic called for 47K. There is no evidence those 2 resistors were ever changed out. Every other component is by the book, and the output is exactly 10DB higher as measured on the power meter, and by calculation from the RMS reading on a HP AC voltmeter. There is no reference to any authorized changes to the equipment. Could those 12K's be the source of my extra 10DB? I would think 12K would lower the output from 47K's. I never did this test before, never had a manual. Here's another question for those who ever went to an actual soldering class like those given in the military. I was taught that on terminal boards, wires went to the bottom of the terminal, and component to the top to facilitate repair. Alot of my military gear is just the opposite, including this amp. Was wire on bottom/component on top not really a requirement of manufacturers? Charlie, W4MEC in NC From bguyger at yahoo.com Fri Aug 12 11:09:26 2016 From: bguyger at yahoo.com (Bill Guyger) Date: Fri, 12 Aug 2016 15:09:26 +0000 (UTC) Subject: [AMRadio] AM-864/U In-Reply-To: <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> References: <429843097.15143018.1471010435915.JavaMail.yahoo.ref@mail.yahoo.com> <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> Message-ID: <1860571573.13999969.1471014566649.JavaMail.yahoo@mail.yahoo.com> Charlie Not sure about the gain issue, have to mull that one, but the component on the bottom, wire on top probably comes from the terminal board being preassembled?at one production?"station"?then installed in the chassis and wired at another during production. More efficient that way. Bill AD5OL From: CL in NC via AMRadio To: amradio at mailman.qth.net Sent: Friday, August 12, 2016 9:00 AM Subject: [AMRadio] AM-864/U Anybody familiar with this audio amp?? ? Was used in studio applications to maintain a constant audio level output placed between studio equipment and the TX and is apparently still highly sought after when you see what they want for it on ebay. I have owned one for over 45 years, getting it in a govt. surplus sale in 1971 at NAS JAX,? and have used it on an off for different things, but now want to use it in earnest in a homebrew TX project.? Dragged it out and went through it, replacing all the coupling caps as they were all leaking, and performed the alignment procedures.? Putting in -35db (.066 volts) at 1Khz,? it is only supposed to deliver 0 DB? into 600 ohms, and mine gives +10 into a lab audio power meter set to 600 ohms.? It functions exactly buy the book in its regulation function maintaining 0 out over a 10db input swing.? The only thing I found was the plate resistors on the input push pull amp tube were 12K, while the schematic called for 47K. There is no evidence those 2 resistors were ever changed out.? Every other component is by the book, and the output is exactly 10DB higher as measured on the power meter, and by calculation from the RMS reading on a HP AC voltmeter. There is no reference to any aut horized changes to the equipment.? Could those 12K's be the source of my extra 10DB?? I would think 12K would lower the output from 47K's.? I never did this test before, never had a manual. Here's another question for those who ever went to an actual soldering class like those given in the military.? I was taught that on terminal boards, wires went to the bottom of the terminal, and component to the top to facilitate repair.? Alot of my military gear is just the opposite, including this amp.? Was wire on bottom/component on top not really a requirement of manufacturers? Charlie, W4MEC in NC ______________________________________________________________ Our Main Website: http://www.amfone.net/ AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net/ Please help support this email list: http://www.qsl.net/donate.html Message delivered to bguyger at yahoo.com From k4kyv at charter.net Fri Aug 12 11:57:22 2016 From: k4kyv at charter.net (Donald Chester) Date: Fri, 12 Aug 2016 10:57:22 -0500 Subject: [AMRadio] AM-864/U In-Reply-To: <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> References: <429843097.15143018.1471010435915.JavaMail.yahoo.ref@mail.yahoo.com> <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> Message-ID: <000101d1f4b2$36587d60$a3097820$@charter.net> > Here's another question for those who ever went to an actual soldering class > like those given in the military. I was taught that on terminal boards, wires > went to the bottom of the terminal, and component to the top to facilitate > repair. Alot of my military gear is just the opposite, including this amp. Was > wire on bottom/component on top not really a requirement of > manufacturers? > > Charlie, W4MEC in NC Something else that has irritated me, particularly with Collins equipment, they often went far beyond the practice of making a "firm mechanical connection before solder is applied". The wire would be threaded through the eye of the terminal lug and wrapped back around several times, each turn threaded through the eyelet, making it impossible to remove a component without destroying the solder lug, and damaging nearby components and wire insulation with the hot soldering iron while trying to get the thing apart. I don't even do the "firm mechanical connection" bit if I don't have to. I usually just poke the wire through the eyelet, with or without a hook, and then apply solder. If the connection holds together long enough for soldering, the wire itself will break in two long before the soldered connection pulls apart. I sometimes wrap the wire a little less than one complete turn when several connections are to be made to the same terminal, so that none of the wires fall out before the last one is inserted and solder applied. I try to make anything I build as easy to disassemble as possible, to facilitate future wiring changes or repair. Don k4kyv From jay.walker.voiceover at gmail.com Fri Aug 12 12:16:05 2016 From: jay.walker.voiceover at gmail.com (Jay Walker) Date: Fri, 12 Aug 2016 11:16:05 -0500 Subject: [AMRadio] Dayton Message-ID: An interesting point was brought up on the "What is it" comments you hear when manning a table at a tailgate sale. You can always tell a 'newb' when you see one asking "What kind of tube is that?" when pointing at a vacuum variable capacitor. ?That said, we ALL were 'newbs' once so I always do my best to suppress the urge to laugh and explain what an item 'is' and is used for.? Today's tests are a bit lacking in technical area these days so it's really not surprising. I had an interesting QSO the other day with a new 7 day wonder extra (?) who was bemoaning the lack of step by step tuning instructions in a Viking Valiant manual. I had to explain in general it was understood 'back in the day' that after passing a test one would know to dip the plate current etc. As it was in past decades and is now today, the real knowledge only begins when you put your first station on the air. VRY 73 de NS5F *Sent from my Commodore 64 Plus...* From bguyger at yahoo.com Fri Aug 12 12:27:26 2016 From: bguyger at yahoo.com (Bill Guyger) Date: Fri, 12 Aug 2016 16:27:26 +0000 (UTC) Subject: [AMRadio] AM-864/U In-Reply-To: <000101d1f4b2$36587d60$a3097820$@charter.net> References: <429843097.15143018.1471010435915.JavaMail.yahoo.ref@mail.yahoo.com> <429843097.15143018.1471010435915.JavaMail.yahoo@mail.yahoo.com> <000101d1f4b2$36587d60$a3097820$@charter.net> Message-ID: <513455993.13218269.1471019246741.JavaMail.yahoo@mail.yahoo.com> Yeah, those multiple wraps around a terminal can be a pain. I'm sort of in the middle on this, on those terminal strips with the terminals spaced apart on a Bakelite strip I do crimp the wire around the lug once because the hole is so large, ditto for toggle switch lugs especially the?larger 15-20 Amp?ones. But if you stop to think, on thru the?hole?Printed Circuit Boards (vs. surface mount)?you just insert the lead and solder without a "firm mechanical connection" same for XLR connectors and the center contacts of many coax connectors (even some where the shield is crimped), etc. Bill AD5OL From: Donald Chester To: amradio at mailman.qth.net Sent: Friday, August 12, 2016 10:57 AM Subject: Re: [AMRadio] AM-864/U > Here's another question for those who ever went to an actual soldering class > like those given in the military.? I was taught that on terminal boards, wires > went to the bottom of the terminal, and component to the top to facilitate > repair.? Alot of my military gear is just the opposite, including this amp.? Was > wire on bottom/component on top not really a requirement of > manufacturers? > > Charlie, W4MEC in NC Something else that has irritated me, particularly with Collins equipment, they often went far beyond the practice of making a "firm mechanical connection before solder is applied". The wire would be threaded through the eye of the terminal lug and wrapped back around several times, each turn threaded through the eyelet, making it impossible to remove a component without destroying the solder lug, and damaging nearby components and wire insulation with the hot soldering iron while trying to? get the thing apart. I don't even do the "firm mechanical connection" bit if I don't have to. I usually just poke the wire through the eyelet, with or without a hook, and then apply solder. If the connection holds together long enough for soldering, the wire itself will break in two long before the soldered connection pulls apart.? I sometimes wrap the wire a little less than one complete turn when several connections are to be made to the same terminal, so that none of the wires fall out before the last one is inserted and solder applied.? I try to make anything I build as easy to disassemble as possible, to facilitate future wiring changes or repair. Don k4kyv ______________________________________________________________ Our Main Website: http://www.amfone.net/ AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net/ Please help support this email list: http://www.qsl.net/donate.html Message delivered to bguyger at yahoo.com From mjcal77 at yahoo.com Fri Aug 12 22:35:35 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Sat, 13 Aug 2016 02:35:35 +0000 (UTC) Subject: [AMRadio] AM-864/U output finale References: <2132167616.15703665.1471055735168.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <2132167616.15703665.1471055735168.JavaMail.yahoo@mail.yahoo.com> Well, after reading the alignment procedure again, it says with -35db in, you should get no less than 0db out across 600 ohms. The manual does not give an upper limit, so, +10db is definitely more than 0. Guess this may fall in the 'weasel word' category. The 12K resistor mix up may be a typo. On the plate side, the schematic calls for 47K, then passing through the coupling caps to the grid side of the push-pull output stage, there actually are 2 - 47K resistors as shown in the schematic. This is about the only military manual I have seen that does not include a descriptive parts list, so have nothing to double check with. Charlie, W4MEC in NC From mjcal77 at yahoo.com Sat Aug 13 21:55:58 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Sun, 14 Aug 2016 01:55:58 +0000 (UTC) Subject: [AMRadio] Everyone know this but me? References: <307817241.16119656.1471139758989.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> Doing research on boost/buck transformers, I learned that it is not the 120 volt load that determines the KVA needed, but the load on the lower voltage winding that does the boosting or bucking. This only applies when wired as an auto- transformer, SOLA rates their 120 volt .25KVA unit at 20.8 amps at 120 volts. You can put your whole vintage station on one and get 1950's 110 VAC for 50 bucks or so for this size unit from several sources. Check it out at: http://www.emersonindustrial.com/en-US/documentcenter/EGSElectricalGroup/products_documents/control_power_solutions/xformers/buck_boost_xformer/buckboost-xformers/buck_boost_transformer_catalog_pages.pdf Charlie W4MEC in NC From k4kyv at charter.net Sun Aug 14 00:13:59 2016 From: k4kyv at charter.net (Donald Chester) Date: Sat, 13 Aug 2016 23:13:59 -0500 Subject: [AMRadio] Everyone know this but me? In-Reply-To: <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> References: <307817241.16119656.1471139758989.JavaMail.yahoo.ref@mail.yahoo.com> <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> Message-ID: <001501d1f5e2$48b9b880$da2d2980$@charter.net> > Doing research on boost/buck transformers, I learned that it is not the 120 > volt load that determines the KVA needed, but the load on the lower voltage > winding that does the boosting or bucking. This only applies when wired as > an auto- transformer, SOLA rates their 120 volt .25KVA unit at 20.8 amps at > 120 volts. You can put your whole vintage station on one and get 1950's 110 > VAC for 50 bucks or so for this size unit from several sources. A 10-volt 20-amp filament transformer will work just fine. If 10 volts is not exactly the bucking voltage you need, you can feed the primary of the filament transformer with a much smaller variac, to adjust the total output voltage to just the right value. A variac feeding the load directly does the most work when the voltage is adjusted somewhere around mid-scale. If the voltage is set close to zero or nearly to maximum, the variac does very little work. In fact, if the output voltage of the variac is set to exactly the same is the line voltage, the variac does no work at all, merely acting as an inductor bridged across the power mains. Don k4kyv From ranchorobbo at gmail.com Sun Aug 14 08:44:14 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Sun, 14 Aug 2016 07:44:14 -0500 Subject: [AMRadio] Everyone know this but me? In-Reply-To: <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> References: <307817241.16119656.1471139758989.JavaMail.yahoo.ref@mail.yahoo.com> <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> Message-ID: There's a lot here I am not getting. On Sat, Aug 13, 2016 at 8:55 PM, CL in NC via AMRadio wrote: > Doing research on boost/buck transformers, I learned that it is not the 120 volt load that determines the KVA needed, but the load on >the lower voltage winding that does the boosting or bucking. When you write "buck/boost transformer" I picture a single winding with a common and line pair of taps and another tap above or below the line tap that goes to the load. The "lower voltage winding" would be the same winding because there's only one winding. > This only applies when wired as an auto- transformer, > An "auto-transformer" is what I just described > SOLA rates their 120 volt .25KVA unit at 20.8 amps at 120 volts. SOLA makes these devices that hold the v. to the load at a constant amount while the line v. can move up and down. I can't remember how they work, only that they hum loudly and give off a lot of heat. Is this the kind of device you are talking about? > You can put your whole vintage station on one and get 1950's 110 VAC for 50 bucks or so for this size unit from several sources. > Well, 21 amps @ 120 v. is around 2500 watts so that should run a couple 100 watt rigs and a receiver or two but I don't know where the .25KVA comes from. So as I said, there's a lot I am missing here. 73 Rob K5UJ From mjcal77 at yahoo.com Sun Aug 14 10:17:01 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Sun, 14 Aug 2016 14:17:01 +0000 (UTC) Subject: [AMRadio] Boost/buck from the horses mouth References: <1922080175.4816714.1471184221069.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <1922080175.4816714.1471184221069.JavaMail.yahoo@mail.yahoo.com> Here's the SOLA site with all the details if interested: http://www.emersonindustrial.com/en-US/documentcenter/EGSElectricalGroup/products_documents/control_power_solutions/xformers/buck_boost_xformer/buckboost-xformers/buck_boost_transformer_catalog_pages.pdf No, these xfmrs do not hum loudly like the SOLA voltage regulators. Charlie From mjcal77 at yahoo.com Sun Aug 14 10:38:33 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Sun, 14 Aug 2016 14:38:33 +0000 (UTC) Subject: [AMRadio] Just had to send this... References: <1748800858.16188747.1471185513236.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <1748800858.16188747.1471185513236.JavaMail.yahoo@mail.yahoo.com> Was looking for some info on a radio and found this site. Did you know you can put a bunch of old parts in a glass of some sort, and sell them as antique art work? Check this out: https://www.1stdibs.com/furniture/more-furniture-collectibles/scientific-instruments/television-electronic-components-circa-mid-century-displayed-crystal-vase/id-f_5259293/ Well, that glass full of caps is inaccurate as described 'mid century'. Don't think they had polystyrene caps and tantalums of that style in 1950. I going to get all my burned out parts in my vintage 'burned out parts' box and some mason jars and get rich. Charlie From n7rk at cox.net Sun Aug 14 11:39:34 2016 From: n7rk at cox.net (Dave Hollander) Date: Sun, 14 Aug 2016 08:39:34 -0700 Subject: [AMRadio] Just had to send this... In-Reply-To: References: <1748800858.16188747.1471185513236.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <57B090B6.5060208@cox.net> And you probably will get more money if their are black beauties in it. :-) Seriously, I have given several boxes of tubes to a lady artist friend and she has done some neat pieces with them. She has also done some neat pieces with old semiconductors. Dave N7RK -- Dave Hollander N7RK Arizona Tube Supply http://arizonatubesupply.com Ham Radio Page http://n7rk.com From oldradio at comcast.net Sun Aug 14 12:37:04 2016 From: oldradio at comcast.net (oldradio at comcast.net) Date: Sun, 14 Aug 2016 16:37:04 +0000 (UTC) Subject: [AMRadio] Just had to send this... In-Reply-To: <1748800858.16188747.1471185513236.JavaMail.yahoo@mail.yahoo.com> References: <1748800858.16188747.1471185513236.JavaMail.yahoo.ref@mail.yahoo.com> <1748800858.16188747.1471185513236.JavaMail.yahoo@mail.yahoo.com> Message-ID: <1784262708.4131651.1471192624263.JavaMail.zimbra@comcast.net> CL, Mason jars are larger, you should be able to charge more $$. 73, John ----- Original Message ----- From: "CL in NC via AMRadio" To: amradio at mailman.qth.net Sent: Sunday, August 14, 2016 10:38:33 AM Subject: [AMRadio] Just had to send this... Was looking for some info on a radio and found this site. Did you know you can put a bunch of old parts in a glass of some sort, and sell them as antique art work? Check this out: https://www.1stdibs.com/furniture/more-furniture-collectibles/scientific-instruments/television-electronic-components-circa-mid-century-displayed-crystal-vase/id-f_5259293/ Well, that glass full of caps is inaccurate as described 'mid century'. Don't think they had polystyrene caps and tantalums of that style in 1950. I going to get all my burned out parts in my vintage 'burned out parts' box and some mason jars and get rich. Charlie ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to oldradio at comcast.net From k4kyv at charter.net Sun Aug 14 15:43:23 2016 From: k4kyv at charter.net (Donald Chester) Date: Sun, 14 Aug 2016 14:43:23 -0500 Subject: [AMRadio] Everyone know this but me? In-Reply-To: References: <307817241.16119656.1471139758989.JavaMail.yahoo.ref@mail.yahoo.com> <307817241.16119656.1471139758989.JavaMail.yahoo@mail.yahoo.com> Message-ID: <001c01d1f664$1e798d20$5b6ca760$@charter.net> > From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of > Rob Atkinson > There's a lot here I am not getting. > > When you write "buck/boost transformer" I picture a single winding with a > common and line pair of taps and another tap above or below the line tap > that goes to the load. The "lower voltage winding" would be the same > winding because there's only one winding. The buck/boost transformer would be low-voltage high current, perhaps a filament transformer, with separate primary and secondary windings. The primary is connected directly to the a.c. mains outlet. The LV secondary is wired in series between the "hot" side of the line and the load, while the neutral (or the other hot if it's wired for 230V) is connected to the load. In other words, the low voltage output from the filament winding is wired in series with the output from the a.c. mains , so that it either adds or subtracts from the mains voltage, depending on polarity. A second way to hook it up would be to connect the hot side of the filament transformer primary so that it is in parallel with the load, in series with the filament winding, instead of directly to the hot mains wire. In that case it is made to function as an autotransformer. I always preferred the former configuration, but they should each work equally well but give slightly different output voltages, so it might be well to try both configurations to see which one comes closer to the desired net output voltage. > SOLA makes these devices that hold the v. to the load at a constant amount > while the line v. can move up and down. I can't remember how they work, > only that they hum loudly and give off a lot of heat. Is this the kind of device > you are talking about? Those things are inefficient and tend to be acoustically noisy. They have two secondaries; one close to 1:1 turns ratio for the load, and the other a HV winding with enough capacitance connected in parallel with the winding, to form a tuned circuit at line frequency. The unloaded resonant circuit pulls a lot of current at each peak of the cycle, enough to drive the core into saturation. The saturated core is what limits the voltage from the 1:1 turns ratio winding. One problem is that the output isn't a pure sine wave but maybe more like a square wave, and in some equipment power supply circuits this may cause weirdness or other problems. I have a small one of those, rated at 75 V-A, which is actually very quiet. I use it to run my 75A-4. It was manufactured more recently, sometime in the 1980s, designed to run a desktop computer in an office setting, so they evidently went out of their way to make it quiet. A Dayton flea market find. > Well, 21 amps @ 120 v. is around 2500 watts so that should run a couple 100 > watt rigs and a receiver or two but I don't know where the .25KVA comes > from. Using a 120v primary/10v 20A secondary filament transformer as an example, since the filament winding is in series with the power mains, it is supplying full current (20 amps), but only at its rated output voltage ( 10 volts), the load on the transformer is .200 KVA (10v times 20 amps) ; it's supplying only a small fraction of the total power delivered to the load. Connected to boost mode, the above configuration would boost the 120v line to 130 volts. In buck mode, it would reduce it to 110v. The load would be pulling a net total of either 2.60 KVA (in boost mode) or 2.20 KVA (in buck mode), but the buck/boost transformer is not supplying the full load. It's just suppling enough voltage (at 20 amps) to correct the voltage delivered to the load. Don k4kyv From tobiebw2 at newmexico.com Tue Aug 16 00:08:37 2016 From: tobiebw2 at newmexico.com (Steve Wender) Date: Mon, 15 Aug 2016 22:08:37 -0600 Subject: [AMRadio] Viking Valiant frequency knob play Message-ID: Hi all, Any thoughts on fixing the play in my valiant VFO control. It seems to be mechanical. I can move the dial a little and there is no motion in the tuning cap. I can't really see without dismantling the VFO shield what is going on. It seems like the linkage is loose but the set screws are tight on the shaft. Is there a coupling spider in there that is loose? Or am I asking too much for a 60 year old rig and maybe I should put it back together and just enjoy using it. Thanks, Steve KC5WN From jayw5jay at cox.net Tue Aug 16 01:15:42 2016 From: jayw5jay at cox.net (Jay Bromley) Date: Tue, 16 Aug 2016 00:15:42 -0500 Subject: [AMRadio] Viking Valiant frequency knob play In-Reply-To: References: Message-ID: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> Sounds like you broke the bakelite flex coupling that drives the cap. Pain in the backside to fix, you have to take off the knobs and front panel. Some guys repair the broken bakelite with circuit board material or find a good junkbox that has a coupling that will work. I don't remember the issue, but I think in Electric Radio had an article on how to repair the coupling. 73 de w5jay.. >>>>Hi all, Any thoughts on fixing the play in my valiant VFO control. It seems to be mechanical. I can move the dial a little and there is no motion in the tuning cap. I can't really see without dismantling the VFO shield what is going on. It seems like the linkage is loose but the set screws are tight on the shaft. Is there a coupling spider in there that is loose? Or am I asking too much for a 60 year old rig and maybe I should put it back together and just enjoy using it. Thanks, Steve KC5WN ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jayw5jay at cox.net From ranchorobbo at gmail.com Tue Aug 16 06:08:33 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Tue, 16 Aug 2016 05:08:33 -0500 Subject: [AMRadio] Viking Valiant frequency knob play In-Reply-To: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> References: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> Message-ID: Can't you just use a standard porcelain insulated shaft coupler? Rob K5UJ On Tue, Aug 16, 2016 at 12:15 AM, Jay Bromley wrote: > Sounds like you broke the bakelite flex coupling that drives the cap. Pain > in the backside to fix, you have to take off the knobs and front panel. > Some guys repair the broken bakelite with circuit board material or find a > good junkbox that has a coupling that will work. From oneets123 at gmail.com Tue Aug 16 12:13:57 2016 From: oneets123 at gmail.com (Larry Oneets) Date: Tue, 16 Aug 2016 11:13:57 -0500 Subject: [AMRadio] Buck/Boost transformer Message-ID: I have used an old 6 volt battery charger transformer for years on my bench to drop the line voltage to most all of my equipment with no problems. The load current can be no more than what the secondary is able to carry and that is why a discarded (really cheap) battery charger transformer will work well and last a very long time. Try it you just may like it. Larry K9LWI From ranchorobbo at gmail.com Tue Aug 16 13:06:00 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Tue, 16 Aug 2016 12:06:00 -0500 Subject: [AMRadio] Buck/Boost transformer In-Reply-To: References: Message-ID: I've used the filament windings in series to buck line down to 112 or so from 123 v. by using the 6 and 5 v. secondary windings with the primary, on one of the standard small power supply transformers that has a 115 v. primary and a 700 VCT secondary plus the filament secondaries. I think the way it works is that in buck mode the pair of filament windings at 11 v. in reverse "polarity" partially cancels the magnetic field but I can't remember how I wired it all up now. I think you connect the neutral return to one end of the primary winding and connect one end of what is now the 11 v. coil to the other end of the primary that is free, then connect the hot line in to the unused end of the 11 v. winding. I know, it's all as clear as "Get the vector Victor." I'd have to mess around with it using a v. meter to figure it out again. Rob K5UJ From jayw5jay at cox.net Thu Aug 18 03:33:35 2016 From: jayw5jay at cox.net (Jay Bromley) Date: Thu, 18 Aug 2016 02:33:35 -0500 Subject: [AMRadio] Viking Valiant frequency knob play In-Reply-To: References: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> Message-ID: <00de01d1f922$d51a7420$7f4f5c60$@cox.net> Hi Rob, I would think so if there is room to do that. I've been lucky so far and never broke one. Surely someone that has tried this would comment? This a good case just to use a DDS VFO and bypass the original VFO, :-) 73 de jay/w5jay.. Can't you just use a standard porcelain insulated shaft coupler? Rob K5UJ On Tue, Aug 16, 2016 at 12:15 AM, Jay Bromley wrote: > Sounds like you broke the bakelite flex coupling that drives the cap. > Pain in the backside to fix, you have to take off the knobs and front panel. > Some guys repair the broken bakelite with circuit board material or > find a good junkbox that has a coupling that will work. From hbrnut at suddenlink.net Thu Aug 18 05:45:05 2016 From: hbrnut at suddenlink.net (WA5VGO) Date: Thu, 18 Aug 2016 04:45:05 -0500 Subject: [AMRadio] Viking Valiant frequency knob play In-Reply-To: <00de01d1f922$d51a7420$7f4f5c60$@cox.net> References: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> <00de01d1f922$d51a7420$7f4f5c60$@cox.net> Message-ID: I think Johnson used an odd-ball reducer coupling - 1/4" X 3/16". This pretty much forces you to stick with the original. Darrell > On Aug 18, 2016, at 2:33 AM, Jay Bromley wrote: > > Hi Rob, > I would think so if there is room to do that. I've been lucky so far and never broke one. Surely someone that has tried this would comment? > > This a good case just to use a DDS VFO and bypass the original VFO, :-) > > > 73 de jay/w5jay.. > > > Can't you just use a standard porcelain insulated shaft coupler? > > Rob > K5UJ > >> On Tue, Aug 16, 2016 at 12:15 AM, Jay Bromley wrote: >> Sounds like you broke the bakelite flex coupling that drives the cap. >> Pain in the backside to fix, you have to take off the knobs and front panel. >> Some guys repair the broken bakelite with circuit board material or >> find a good junkbox that has a coupling that will work. > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Archives: http://mailman.qth.net/pipermail/amradio/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: AMRadio at mailman.qth.net > To unsubscribe, send an email to amradio-request at mailman.qth.net with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to hbrnut at suddenlink.net From tobiebw2 at newmexico.com Thu Aug 18 09:40:21 2016 From: tobiebw2 at newmexico.com (Steve Wender) Date: Thu, 18 Aug 2016 07:40:21 -0600 Subject: [AMRadio] Play in Valiant VFO knob Message-ID: <93f7513e-f00f-776c-4516-b0875e193e58@newmexico.com> Hi All, Well, I am still working on fixing the Valiant VFO play in the VFO. I took the front panel off and a lot of the VFO shielding to look at the coupling. There is a bakalite spider that goes from 3/16" shaft on the variable cap to 1/4 inch reducing gear mechanism which goes to the dial. The bakalite spider was broken and needs to be replaced. Any one have one around? I have a choice of repairing the spider-- I need a new bakalite piece or using a direct metal coupling. I think i can make a coupling out of metal because I think the rotor of the cap is at ground but I will not have the flexibility in the drive shaft. I can try to repair the spider by drilling out the rivets and replacing the bakalite sheet-- have to find some bakalite sheet or use something else. Any thougths? The fun continues. Steve KC5WN From k6xyz at sbcglobal.net Thu Aug 18 10:20:00 2016 From: k6xyz at sbcglobal.net (David Harmon) Date: Thu, 18 Aug 2016 09:20:00 -0500 Subject: [AMRadio] Play in Valiant VFO knob In-Reply-To: <93f7513e-f00f-776c-4516-b0875e193e58@newmexico.com> References: <93f7513e-f00f-776c-4516-b0875e193e58@newmexico.com> Message-ID: <000201d1f95b$9d0b03e0$d7210ba0$@sbcglobal.net> I believe someone previously mentioned thin unclad .008" to .010" thick ckt board material. Flexible but still very tough. Check the archives. 73 David Harmon K6XYZ Sperry, OK -----Original Message----- From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Steve Wender Sent: Thursday, August 18, 2016 8:40 AM To: Discussion of AM Radio in the Amateur Service Subject: [AMRadio] Play in Valiant VFO knob Hi All, Well, I am still working on fixing the Valiant VFO play in the VFO. I took the front panel off and a lot of the VFO shielding to look at the coupling. There is a bakalite spider that goes from 3/16" shaft on the variable cap to 1/4 inch reducing gear mechanism which goes to the dial. The bakalite spider was broken and needs to be replaced. Any one have one around? I have a choice of repairing the spider-- I need a new bakalite piece or using a direct metal coupling. I think i can make a coupling out of metal because I think the rotor of the cap is at ground but I will not have the flexibility in the drive shaft. I can try to repair the spider by drilling out the rivets and replacing the bakalite sheet-- have to find some bakalite sheet or use something else. Any thougths? The fun continues. Steve KC5WN ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to k6xyz at sbcglobal.net From ne1s at securespeed.us Thu Aug 18 10:48:05 2016 From: ne1s at securespeed.us (Larry Szendrei) Date: Thu, 18 Aug 2016 10:48:05 -0400 Subject: [AMRadio] Play in Valiant VFO knob In-Reply-To: <81c7fcb6-ac30-1095-72cb-afb3f7db346f@securespeed.us> References: <93f7513e-f00f-776c-4516-b0875e193e58@newmexico.com> <000201d1f95b$9d0b03e0$d7210ba0$@sbcglobal.net> <81c7fcb6-ac30-1095-72cb-afb3f7db346f@securespeed.us> Message-ID: I think the circuit board material would be a better solution than metal. Multiple paths from the VFO capacitor rotor to ground, or to the "wrong" ground point, could have unpredictable effects. Not necessarily, but possibly. I'd stick to an insulating material. 73 es GL, -Larry/NE1S On 8/18/16 10:20 AM, David Harmon wrote: > I believe someone previously mentioned thin unclad .008" to .010" > thick ckt > board material. > Flexible but still very tough. > Check the archives. > > > 73 > > David Harmon > K6XYZ > Sperry, OK > > -----Original Message----- > From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Steve > Wender > Sent: Thursday, August 18, 2016 8:40 AM > To: Discussion of AM Radio in the Amateur Service > > Subject: [AMRadio] Play in Valiant VFO knob > > Hi All, > > > Well, I am still working on fixing the Valiant VFO play in the VFO. I > took > the front panel off and a lot of the VFO shielding to look at the > coupling. > There is a bakalite spider that goes from 3/16" shaft on the variable > cap to > 1/4 inch reducing gear mechanism which goes to the dial. The bakalite > spider was broken and needs to be replaced. Any one have one around? I > have a choice of repairing the spider-- I need a new bakalite piece or > using > a direct metal coupling. I think i can make a coupling out of metal > because > I think the rotor of the cap is at ground but I will not have the > flexibility in the drive shaft. I can try to repair the spider by > drilling > out the rivets and replacing the bakalite > sheet-- have to find some bakalite sheet or use something else. Any > thougths? > > The fun continues. > > Steve KC5WN > From ranchorobbo at gmail.com Thu Aug 18 12:40:09 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Thu, 18 Aug 2016 11:40:09 -0500 Subject: [AMRadio] Play in Valiant VFO knob In-Reply-To: References: <93f7513e-f00f-776c-4516-b0875e193e58@newmexico.com> <000201d1f95b$9d0b03e0$d7210ba0$@sbcglobal.net> <81c7fcb6-ac30-1095-72cb-afb3f7db346f@securespeed.us> Message-ID: I'd try to repair the bakelite with two ton clear epoxy. It's just turning a small variable cap right? Rob K5UJ From jayw5jay at cox.net Thu Aug 18 18:28:25 2016 From: jayw5jay at cox.net (Jay Bromley) Date: Thu, 18 Aug 2016 17:28:25 -0500 Subject: [AMRadio] Viking Valiant frequency knob play References: <00bc01d1f77d$3c8b7480$b5a25d80$@cox.net> Message-ID: <007201d1f99f$d64816e0$82d844a0$@cox.net> Hi Steve, Looks like Ebay could be your friend in this instance? http://www.ebay.com/itm/Johnson-Viking-500-Ranger-Valiant-Pacemaker-Navigator-VFO-coupler-repair-kit-/331939955110?hash=item4d4929c1a6:g:iVEAAOSwBadTo67P 73 de jay/w5jay.. From mjcal77 at yahoo.com Mon Aug 22 22:20:08 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Tue, 23 Aug 2016 02:20:08 +0000 (UTC) Subject: [AMRadio] Sound advice References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> I have been wanting to experiment with some of my old mics that basically sound pretty bad, either too tinny or too bass, (not the fish) and run them through a graphic equalizer.? The motivation for this is that I found a really nice single channel, 32 filter unit for a song, but it does not have enough sensitivity to handle crystal, dynamic, or controlled magnetic mics, giving only minimal indication on the output bar graph at high voice input, so I need some ooomph on the head end.? A homebrew 12AX7 amp to fit between my various basket case mics and the equalizer is required. Does anybody have experience in this area with some pointers? Ideas on a solid state preamp instead of a tube? I checked several designs online and the ones in the 'Encyclopedia of Electronic Circuits', but maybe somebody here has a bullet proof schematic. The DBK2031 equalizer performs as it spec sheet advertises, handling inputs and outputs to 40K loads. Charlie, W4MEC in NC From w5jo at brightok.net Mon Aug 22 23:17:02 2016 From: w5jo at brightok.net (w5jo at brightok.net) Date: Mon, 22 Aug 2016 22:17:02 -0500 Subject: [AMRadio] Sound advice In-Reply-To: <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> Message-ID: <3D38D40128704FB4B629D7E6EFC0A5C7@JimPC> Charlie, If you have an RCA Receiving Tube Manual, I believe there is a simple diagram in the back of it that will do what you need. You will want an RC-23 or before. 73, Jim W5JO -----Original Message----- I have been wanting to experiment with some of my old mics that basically sound pretty bad, either too tinny or too bass, (not the fish) and run them through a graphic equalizer. The motivation for this is that I found a really nice single channel, 32 filter unit for a song, but it does not have enough sensitivity to handle crystal, dynamic, or controlled magnetic mics, giving only minimal indication on the output bar graph at high voice input, so I need some ooomph on the head end. A homebrew 12AX7 amp to fit between my various basket case mics and the equalizer is required. Does anybody have experience in this area with some pointers? Ideas on a solid state preamp instead of a tube? I checked several designs online and the ones in the 'Encyclopedia of Electronic Circuits', but maybe somebody here has a bullet proof schematic. The DBK2031 equalizer performs as it spec sheet advertises, handling inputs and outputs to 40K loads. Charlie, W4MEC in NC From ranchorobbo at gmail.com Tue Aug 23 06:04:09 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Tue, 23 Aug 2016 05:04:09 -0500 Subject: [AMRadio] Sound advice In-Reply-To: <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> Message-ID: Equalizers accept line level audio, not mic level. You have to have a mic preamp to get it to line level ahead of the equalizer. I went through a lot of this last summer. Look for a vintage tube amplifier usually called a speech amp, mixer, or preamp. Besides 12AX7 you can use 6SC7s if you want a larger octal size to deal with. The two triodes in one of those tubes will get you up to line level. Put a pot between the first triode and the second to vary gain. As Jim wrote, look at circuits in tube manuals to get an idea. Here's the good and bad news: The good news is that you can have as many dual triodes as you want, each with its own input and pot going out to the equalizer, and on each one's input you can put a grid resistor that matches the nominal mic impedance. Crystal would take 10 megohm, dynamic maybe 50K depending on when it was made--the new ones are low impedance but you wrote "old mics" so I'm guessing maybe 50 to 100K for the dynamics. Easy. The bad news is that the equalizer may be one of these boxes that takes a 600 ohm balanced input. If so, you have to find a way to step down the high Z of the tube plate (via a dc blocking cap) to the input of the driven circuit and get from unbalanced to balanced audio. I took a UTC LS27 (or maybe it was a 26) that was around 5K to 60K and flipped it to step the tube down to lower impedance. The ends of the former primary now secondary became the + and - balanced leads into the stage being driven with ground to the transformer case. This does several things. It gets your impedance down to a level that is close enough to the next item being driven, transfers from unbalanced to balanced audio, and isolates the two so RF and ground loop problems don't occur. If you don't do some kind of impedance step down your audio will sound tinny with no low frequency at all. Another gotcha to avoid--don't directly ground the cathodes in the preamp. It will work great until you transmit RF then everything will fall apart. Went through all of this last summer, hi. 73 Rob K5UJ On Mon, Aug 22, 2016 at 9:20 PM, CL in NC via AMRadio wrote: > I have been wanting to experiment with some of my old mics that basically sound pretty bad, either too tinny or too bass, (not the fish) and run them through a graphic equalizer. The motivation for this is that I found a really nice single channel, 32 filter unit for a song, but it does not have enough sensitivity to handle crystal, dynamic, or controlled magnetic mics, giving only minimal indication on the output bar graph at high voice input, so I need some ooomph on the head end. A homebrew 12AX7 amp to fit between my various basket case mics and the equalizer is required. Does anybody have experience in this area with some pointers? Ideas on a solid state preamp instead of a tube? I checked several designs online and the ones in the 'Encyclopedia of Electronic Circuits', but maybe somebody here has a bullet proof schematic. The DBK2031 equalizer performs as it spec sheet advertises, handling inputs and outputs to 40K loads. > > Charlie, W4MEC in NC From jayw5jay at gmail.com Tue Aug 23 15:29:56 2016 From: jayw5jay at gmail.com (Jay Bromley) Date: Tue, 23 Aug 2016 14:29:56 -0500 Subject: [AMRadio] Sound advice In-Reply-To: References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> Message-ID: <038e01d1fd74$bb967b10$32c37130$@gmail.com> HI Rob, Couldn't you use a cathode follower if one didn't have a transformer on hand? I had a few of the LS jobs here and they didn't always sweep that great compared to the modern day Jensens line of transformers. Those could have been bad and why they ended up in my junk box, hi 73 de w5jay/jay.. Rob wrote>>> Equalizers accept line level audio, not mic level. You have to have a mic preamp to get it to line level ahead of the equalizer. I went through a lot of this last summer. Look for a vintage tube amplifier usually called a speech amp, mixer, or preamp. Besides 12AX7 you can use 6SC7s if you want a larger octal size to deal with. The two triodes in one of those tubes will get you up to line level. Put a pot between the first triode and the second to vary gain. As Jim wrote, look at circuits in tube manuals to get an idea. Here's the good and bad news: The good news is that you can have as many dual triodes as you want, each with its own input and pot going out to the equalizer, and on each one's input you can put a grid resistor that matches the nominal mic impedance. Crystal would take 10 megohm, dynamic maybe 50K depending on when it was made--the new ones are low impedance but you wrote "old mics" so I'm guessing maybe 50 to 100K for the dynamics. Easy. The bad news is that the equalizer may be one of these boxes that takes a 600 ohm balanced input. If so, you have to find a way to step down the high Z of the tube plate (via a dc blocking cap) to the input of the driven circuit and get from unbalanced to balanced audio. I took a UTC LS27 (or maybe it was a 26) that was around 5K to 60K and flipped it to step the tube down to lower impedance. The ends of the former primary now secondary became the + and - balanced leads into the stage being driven with ground to the transformer case. This does several things. It gets your impedance down to a level that is close enough to the next item being driven, transfers from unbalanced to balanced audio, and isolates the two so RF and ground loop problems don't occur. If you don't do some kind of impedance step down your audio will sound tinny with no low frequency at all. Another gotcha to avoid--don't directly ground the cathodes in the preamp. It will work great until you transmit RF then everything will fall apart. Went through all of this last summer, hi. 73 Rob K5UJ On Mon, Aug 22, 2016 at 9:20 PM, CL in NC via AMRadio wrote: > I have been wanting to experiment with some of my old mics that basically sound pretty bad, either too tinny or too bass, (not the fish) and run them through a graphic equalizer. The motivation for this is that I found a really nice single channel, 32 filter unit for a song, but it does not have enough sensitivity to handle crystal, dynamic, or controlled magnetic mics, giving only minimal indication on the output bar graph at high voice input, so I need some ooomph on the head end. A homebrew 12AX7 amp to fit between my various basket case mics and the equalizer is required. Does anybody have experience in this area with some pointers? Ideas on a solid state preamp instead of a tube? I checked several designs online and the ones in the 'Encyclopedia of Electronic Circuits', but maybe somebody here has a bullet proof schematic. The DBK2031 equalizer performs as it spec sheet advertises, handling inputs and outputs to 40K loads. > > Charlie, W4MEC in NC ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jayw5jay at gmail.com From ranchorobbo at gmail.com Tue Aug 23 16:53:56 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Tue, 23 Aug 2016 15:53:56 -0500 Subject: [AMRadio] Sound advice In-Reply-To: <038e01d1fd74$bb967b10$32c37130$@gmail.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> <038e01d1fd74$bb967b10$32c37130$@gmail.com> Message-ID: Jay, That is a good suggestion provided it produces enough drive for the next box in the chain. You can also make it a phase splitter. 73 Rob K5UJ On Tue, Aug 23, 2016 at 2:29 PM, Jay Bromley wrote: > HI Rob, > Couldn't you use a cathode follower if one didn't have a transformer on > hand? I had a few of the LS jobs here and they didn't always sweep that > great compared to the modern day Jensens line of transformers. Those could > have been bad and why they ended up in my junk box, hi > > 73 de w5jay/jay.. > From ranchorobbo at gmail.com Tue Aug 23 16:54:01 2016 From: ranchorobbo at gmail.com (Rob Atkinson) Date: Tue, 23 Aug 2016 15:54:01 -0500 Subject: [AMRadio] Sound advice In-Reply-To: References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> Message-ID: p.s. I just read that you also asked about solid state. I don't know much about that at all, except that you'll need RF bypass caps to ground on all the inputs and outputs, .01 or .001 ceramics work, use balanced audio cable that's shielded, and use 1:1 isolation transformers on the audio ins and outs if necessary. Rob K5UJ From Foltarz at rocketmail.com Tue Aug 23 17:21:28 2016 From: Foltarz at rocketmail.com (Mark Foltarz) Date: Tue, 23 Aug 2016 21:21:28 +0000 (UTC) Subject: [AMRadio] DX on demand In-Reply-To: <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> Message-ID: <1694384765.10030278.1471987288110.JavaMail.yahoo@mail.yahoo.com> ? This is a novel idea for when 10 meters is dead.... http://www.dailymail.co.uk/sciencetech/article-3753417/The-Air-Force-reveals-radical-plan-bomb-sky-improve-radio-reception.html From bguyger at yahoo.com Tue Aug 23 17:39:09 2016 From: bguyger at yahoo.com (Bill Guyger) Date: Tue, 23 Aug 2016 21:39:09 +0000 (UTC) Subject: [AMRadio] DX on demand In-Reply-To: <1694384765.10030278.1471987288110.JavaMail.yahoo@mail.yahoo.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> <1694384765.10030278.1471987288110.JavaMail.yahoo@mail.yahoo.com> Message-ID: <904565612.1135423.1471988349146@mail.yahoo.com> That's kind of what "they" were trying with HAARP. Ionize an area way up high, modulate it with an ultra low frequency signal and then modulate that with data. You could communicate with subs on the other side of the world. If you dig into HAARP you will see that the Air Force was building / operating it, but the Navy was paying for it.? I assume it didn't work all that well which is why it was shut down a couple of years ago and recently turned over to the University of Alaska for research.? FWIW the above is my own hypothesis based on something a person associated with the company who built the transmitters told me. When I asked about the site, all he said was "think Submarines......". Bill AD5OL? From: Mark Foltarz via AMRadio To: "amradio at mailman.qth.net" Sent: Tuesday, August 23, 2016 4:21 PM Subject: [AMRadio] DX on demand ? This is a novel idea for when 10 meters is dead.... http://www.dailymail.co.uk/sciencetech/article-3753417/The-Air-Force-reveals-radical-plan-bomb-sky-improve-radio-reception.html ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Archives: http://mailman.qth.net/pipermail/amradio/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio at mailman.qth.net To unsubscribe, send an email to amradio-request at mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to bguyger at yahoo.com From k4kyv at charter.net Wed Aug 24 14:38:16 2016 From: k4kyv at charter.net (Donald Chester) Date: Wed, 24 Aug 2016 13:38:16 -0500 Subject: [AMRadio] Tron In-Reply-To: <233E48889934AE47B4D95CBA9F9162AD95E4CE47@UGUNHPAFF.easf.csd.disa.mil> References: <233E48889934AE47B4D95CBA9F9162AD95E4CE47@UGUNHPAFF.easf.csd.disa.mil> Message-ID: <003001d1fe36$ad84ddb0$088e9910$@charter.net> > The Tron has spoken with regards to the IC7300. That doesn't surprise me. People have flamed me for using the term 'plastic radio'. Don k4kyv From k4kyv at charter.net Wed Aug 24 14:47:37 2016 From: k4kyv at charter.net (Donald Chester) Date: Wed, 24 Aug 2016 13:47:37 -0500 Subject: [AMRadio] DX on demand In-Reply-To: <1694384765.10030278.1471987288110.JavaMail.yahoo@mail.yahoo.com> References: <690831522.498734.1471918808075.JavaMail.yahoo.ref@mail.yahoo.com> <690831522.498734.1471918808075.JavaMail.yahoo@mail.yahoo.com> <1694384765.10030278.1471987288110.JavaMail.yahoo@mail.yahoo.com> Message-ID: <003b01d1fe37$fc7075a0$f55160e0$@charter.net> > Mark Foltarz via AMRadio > This is a novel idea for when 10 meters is dead.... > http://www.dailymail.co.uk/sciencetech/article-3753417/The-Air-Force- > reveals-radical-plan-bomb-sky-improve-radio-reception.html We should be leery of this idea. There could be unintended consequences. What if it screws up propagation as we know it? Maybe increasing absorption enough to make the lower bands unusable even at night? (Of course, the present-day AM broadcast industry would love to get rid of night-time skywave, so they might lobby for even more seeding.) Or if it ends up having serious environmental effects, perhaps on global temperatures? Don k4kyv From donroden at hiwaay.net Wed Aug 24 14:48:59 2016 From: donroden at hiwaay.net (donroden at hiwaay.net) Date: Wed, 24 Aug 2016 13:48:59 -0500 Subject: [AMRadio] Tron In-Reply-To: <003001d1fe36$ad84ddb0$088e9910$@charter.net> References: <233E48889934AE47B4D95CBA9F9162AD95E4CE47@UGUNHPAFF.easf.csd.disa.mil> <003001d1fe36$ad84ddb0$088e9910$@charter.net> Message-ID: <20160824134859.Horde.XJlcItXi_CkV8r_VdibJbEP@webmail.hiwaay.net> Iconic aint it ? Don W4DNR Quoting Donald Chester : >> The Tron has spoken with regards to the IC7300. > > That doesn't surprise me. People have flamed me for using the term 'plastic > radio'. > > Don k4kyv > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Archives: http://mailman.qth.net/pipermail/amradio/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: AMRadio at mailman.qth.net > To unsubscribe, send an email to amradio-request at mailman.qth.net with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to donroden at hiwaay.net From mjcal77 at yahoo.com Thu Aug 25 10:20:21 2016 From: mjcal77 at yahoo.com (CL in NC) Date: Thu, 25 Aug 2016 14:20:21 +0000 (UTC) Subject: [AMRadio] Sound advice References: <719906317.11131751.1472134821554.JavaMail.yahoo.ref@mail.yahoo.com> Message-ID: <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> To all those who have responded here or direct, thank you for the ideas. If you have ever done research on mic preamps for a project like this, apparently the audiophile crowd that pays 60 bucks for a 12AX7 are just as nutty over mic preamps. While a simple solid state preamp kit can be had for $10 or less, you can fork over $2K bucks for a studio grade single channel mic preamp if you are so inclined, some still being made with 12AX7's. Must have really good specs. Charlie, W4MEC in NC From w5jo at brightok.net Thu Aug 25 12:09:44 2016 From: w5jo at brightok.net (w5jo at brightok.net) Date: Thu, 25 Aug 2016 11:09:44 -0500 Subject: [AMRadio] Sound advice In-Reply-To: <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> References: <719906317.11131751.1472134821554.JavaMail.yahoo.ref@mail.yahoo.com> <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> Message-ID: I guess, Charlie, it is packaging and perception for some people. Wish I had the income to afford a single channel 12AX7 preamp at those rates. Jim W5JO -----Original Message----- To all those who have responded here or direct, thank you for the ideas. If you have ever done research on mic preamps for a project like this, apparently the audiophile crowd that pays 60 bucks for a 12AX7 are just as nutty over mic preamps. While a simple solid state preamp kit can be had for $10 or less, you can fork over $2K bucks for a studio grade single channel mic preamp if you are so inclined, some still being made with 12AX7's. Must have really good specs. Charlie, W4MEC in NC From k4kyv at charter.net Thu Aug 25 13:24:13 2016 From: k4kyv at charter.net (Donald Chester) Date: Thu, 25 Aug 2016 12:24:13 -0500 Subject: [AMRadio] Sound advice In-Reply-To: <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> References: <719906317.11131751.1472134821554.JavaMail.yahoo.ref@mail.yahoo.com> <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> Message-ID: <000001d1fef5$800997d0$801cc770$@charter.net> > If > you have ever done research on mic preamps for a project like this, > apparently the audiophile crowd that pays 60 bucks for a 12AX7 are just as > nutty over mic preamps. > > Charlie, W4MEC in NC You don't have to pay that. Some guy was selling 12AX7s at the Huntsville hamfest for about $9 each. I use 6F5s in my pre-amp. The 6F5, a metal octal tube, is practically identical electrically to one section of a 12AX7, and they have the advantage of two separate tubes that can be swapped around to achieve better balance in a push-pull circuit. Another otherwise identical tube is the 6SF5, which has a different pin-out and the grid comes out at the base instead of a grid cap on top. Don k4kyv From k4kyv at charter.net Thu Aug 25 13:30:35 2016 From: k4kyv at charter.net (Donald Chester) Date: Thu, 25 Aug 2016 12:30:35 -0500 Subject: [AMRadio] Sound advice In-Reply-To: References: <719906317.11131751.1472134821554.JavaMail.yahoo.ref@mail.yahoo.com> <719906317.11131751.1472134821554.JavaMail.yahoo@mail.yahoo.com> Message-ID: <000301d1fef6$63744830$2a5cd890$@charter.net> > Wish I had the income to afford a single channel 12AX7 preamp at those > rates. > > Jim > W5JO I'd bet these guys do. (usual notice to copy/paste into ur browser to avoid line break that kills the link) http://gizmodo.com/obsessed-audiophiles-in-japan-are-installing-their-own-17 85291714?utm_medium=sharefromsite&utm_source=Gizmodo_facebook From oldrotorheadsarge1 at outlook.com Fri Aug 26 12:45:21 2016 From: oldrotorheadsarge1 at outlook.com (Bob Bethman) Date: Fri, 26 Aug 2016 16:45:21 +0000 Subject: [AMRadio] Please ignore! Testing after rebuilding Windows! Message-ID: Please ignore! Testing after rebuilding Windows! Regards, Bob Bethman

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