[AMRadio] 813 tx


Jim candela jcandela at prodigy.net
Sun Oct 31 16:21:21 EST 2004



Chris,

    I cannot operate my ham rig late at night because of today's speakers on
computers, and surround sound movie rooms. The advent of THX, Dolby digital
5.1, has brought a new problem to hams. All those satellite speakers with
built in amplifiers are a nuisance to us all. I had a neighbor with a $2000
set of speakers. These would fire up and talk whenever I was on the air. So
late at night ham activity kept my neighbor awake. He even tried
disconnecting the speakers, and wrapped the wire around the case. My voice
still came out. It was like on the three stooges where the medical intercom
would call out, "calling Dr.'s Larry, Mo, and Curly"..

	That AM rig in the dorm was 30 years ago. I do recall getting RF burns off
the window frame! No good ground at the third level of the building, except
for maybe the radiator pipes, widow frame, and cold water pipe. I think I
just tied the radiator pipe to the rig as a ground to go with the window
frame.

	I too use vinyl LP's and a old Marantz turntable. I use a reworked Sherwood
tube amplifier with a combined FM tuner. That is another story. Here is a
piece of that:

http://pages.prodigy.net/jcandela/Sherwood_S8000/HV_REG/regulator.htm

Regards,
Jim



-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of CHRIS PAPAIOANNOU
Sent: Sunday, October 31, 2004 12:40 PM
To: Discussion of AM Radio
Subject: Re: [AMRadio] 813 tx


Jim,
I don't think that this bulb dummy load radiated RF far away...but
sufficiently far away to provoke the neighbors around to start coming by...a
test once proved me that with a dummy load  my modulation has been heard no
more than about 195 feet.Didn't check out if this distance was more than 195
feet because an other fellow ham who was in his house heard me and this test
ended at this point,because this was the object.But since i believe that
antennas with regular electrical length depending of the frequency are
exactly the opposite of  a dummy load  i guess that this distance couldn't
be a little bit more than these 195 feet.
Regarding that Lear T30 seems that the aluminium window frame was a very
poor counterpoise..did you use at that time any form of rf ground?
I've experienced in the past TVi problems with tube AM rigs due to poor rf
grounds..you can immagine my ma's face when was coming to tell me that was
listening to a strange voice in the tv,something like cat's mew.Then learned
that this was me.
Fortunatelly i never had problems with the neighbors.Generally these
transmissions were midnight transmissions when the most of them were on bed.
FM?My 1st homebrew rig was a 6BQ5 rig.Self  oscillated (COLPITS type).I was
using an FM receiver when trying to tune it.Had homebrewd a 6AK5(5654W) self
oscillated also.With dipoles on the roof made from aluminium pipe.I remember
that had connected 2 transfrmrs with primaries 220V and secondaries 6,3V/2A
secondary to secondary in order to feed the rigs.In this way had no
confluences beetween rf and feeding and no hum.
Vinyl?I don't need to remember it Jim cause even now i still use my old
records..The others here are using digi media.I don't.My amp and tuner are
tube type also.By the others i mean the members of my family.
I really enjoyed your memories and experiences Jim,
Regards,
Chris,SV1DAF.
----- Original Message -----
From: "Jim candela" <jcandela at prodigy.net>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Sunday, October 31, 2004 3:17 PM
Subject: RE: [AMRadio] 813 tx


>
>
> Chris, You mentioned broadcasting music to entertain an audience. If the
> truth be known, some of us on this reflector may have at one time or
another
> done this. I can only speak for myself however. :)
>
> I once had a kilowatt AM rig where with 1000 watts DC input I got 850
watts
> carrier output (about 1983). On a particular Saturday night I installed a
> 600 watt movie projector bulb as a "dummy" load at the top of my 40 foot
> tower. The rig loaded really nicely into that bulb. Wanting to see how it
> looked with modulation I needed a modulation source to modulate the rig
> while I was outside looking at the light. So my first CD player was put to
> use playing some Beatles music. It was amazing how bright that bulb was,
and
> how much neighborhood illumination resulted. I had to quit when the
> neighbors started coming by... I wonder how far that thing radiated RF....
>
> About 10 years earlier when I was a freshman in college, I set up a 80
meter
> ham station in my dorm room. For an antenna I used a 10' whip out the
window
> with a loading coil, and the aluminum window frame was my counterpoise. I
> did work a few hams on AM using my Lear T30 transmitter (4 - 6L6's + 6SN7,
> and 6SJ7). I was received more by the dorm inhabitants on their TV sets
and
> stereo amplifiers however. They shut me down. About this time I was
> experimenting with transistors. With a simple transistor gain tester I
> noticed that the readings would vary when moving the leads of the
transistor
> tester. I had several computer boards, and some of these early silicon
> transistors made excellent VHF oscillators. I conjured up a two transistor
> 100 Mhz transmitter (MO and PA), and amplitude modulated the oscillator.
The
> amplifier was class C, so most of the AM was gone, and FM was the dominate
> modulation. Listening to this on a quality FM receiver startled me when I
> discovered that the quality was excellent. I guess that we had maybe 100
mw
> RF output, and with a dipole on the roof of a 3 story building, this thing
> really got out good. This was the beginning of WRFP, Radio Free
Puterbaugh.
> Every Friday and Saturday night we had a dorm sponsored radio station with
> full campus coverage. Requests would come into the front desk, and with
> dozens of students making their LP's available (remember vinyl?), we had a
> full fledged radio station with pre-recorded commercials. So what started
> out as a ham with a TVI and RFI problem turned into a full fledged radio
> station. The same folk that were mad at me were now actively working on
the
> broadcasting! We did this for several months before the novelty wore off.
>
> Regards,
> Jim
>
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net]On Behalf Of CHRIS PAPAIOANNOU
> Sent: Thursday, October 28, 2004 12:36 PM
> To: Discussion of AM Radio
> Cc: gpritchard at comtechpst.com
> Subject: Re: [AMRadio] 813 tx
>
>
> Legendary tube!About 20-25 yrs ago saw a rack mount homebrew 813 rig in a
> fellow's house..p.s and tx in different pi aluminium chassis one above the
> other...6L6 the oscillator tube,an 807 like buffer and 2 of those 813
> "babes"in parallel like p.a
> The p.a tubes were fed with 1200V on plate,was using an 100 W
> modulator-amp,and had a long wire about 300 feet long...
> I still remember it after all this time gone..
> Btw saw a ham from AZ today morning while was searching in the intrnet who
> has used the tube self-oscillated.A well homebrew rig..and a surprise for
me
> who have never seen this tube working in this way be4.
> 73,Chris,SV1DAF.
> ----- Original Message -----
> From: "George Pritchard" <gpritchard at comtechpst.com>
> To: "'Discussion of AM Radio'" <amradio at mailman.qth.net>
> Sent: Thursday, October 28, 2004 5:45 PM
> Subject: RE: [AMRadio] 813 tx
>
>
> > I had one of those rigs as a kid BEFORE I WAS A HAM. I used it on CB
> > modulated with 811A's. Then I found out about Amateur Radio. A backwards
> > experience. Years later I parted it out, unknowing it was so well
> > documented. I actually traced that thing out and drew the schematic at
16
> > years old. The rig sat at the high school in a corner for years... The
> > instructor gave it to me to male room at the end of June. I spent my
> summer
> > vacation that year on the CB band with that thing. Some of that rig is
> here
> > and there in the shack, sort of a ghost. When I saw it in the 1956
> handbook
> > I bought at a fest... I almost had tears. It WAS the one I had.
> > George
> > AB2KC
> >
> > -----Original Message-----
> > From: amradio-bounces at mailman.qth.net
> > [mailto:amradio-bounces at mailman.qth.net] On Behalf Of CHRIS PAPAIOANNOU
> > Sent: Tuesday, October 26, 2004 5:02 AM
> > To: Discussion of AM Radio
> > Cc: peter A Markavage
> > Subject: Re: [AMRadio] 813 tx
> >
> >
> > tnx Pete..
> > Chris,SV1DAF.
> > ----- Original Message -----
> > From: "peter A Markavage" <manualman at juno.com>
> > To: <amradio at mailman.qth.net>
> > Sent: Tuesday, October 26, 2004 9:02 AM
> > Subject: Re: [AMRadio] 813 tx
> >
> >
> > > Here's some:
> > > http://www.amwindow.org/tech/htm/813/813.htm
> > >
> > > http://www.remote.arrl.org/tis/info/pdf/5401011.pdf
> > >
> > > http://www.remote.arrl.org/tis/info/pdf/5610033.pdf
> > >
> > > http://www.remote.arrl.org/tis/info/pdf/57hb192.pdf
> > >
> > > Doing a "Google" search on "813 transmitter" turned up 49 hits.
> > >
> > > Pete, wa2cwa
> > >
> > >
> > > On Tue, 26 Oct 2004 06:44:32 +0300 "CHRIS  PAPAIOANNOU"
> > > <amateur at ipnet.gr> writes:
> > > > 73 to all group's members around,
> > > > i'm new in this list.My name is Chris,my call is SV1DAF and i'm
> > > > located in Athens,Greece.
> > > > I'm not new in AM..20-25 years ago there was too much AM activity
> > > > here,with homemade tube rigs,in the MW band.Was illegal but there
> > > > was.Then most of the "amateurs"became hams with legal activity in
> > > > the ham bands.The rest of them left the radiowaves.
> > > > Not long ago i started homebrewing again after long time.My homebrew
> > > > rigs now are:
> > > > 1)6V6/807 crystal controlled where the 1st tube is the oscillator
> > > > tube and the 2nd one the pa one.
> > > > 2)6J5/EL34
> > > > I prefer plate modulation and the reasons are known and clear,and
> > > > i'm using an amp with 2 EL504s like output tubes.These are sweep
> > > > tubes.
> > > > I'm now searching for a tx drawing with an 813 tube like pa tube.Any
> > > > replies will be too much appreciated.
> > > > Tnx for the attention paid to my introduction,
> > > > 73,Chris,SV1DAF.
> > >
> > > ________________________________________________________________
> > > Speed up your surfing with Juno SpeedBand.
> > > Now includes pop-up blocker!
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