[AMRadio] RE: GB> Antenna Tuner Wonderings


Donald Chester k4kyv at hotmail.com
Sun Dec 26 20:27:30 EST 2004



>From: "Merz Donald S" <merz.ds at mellon.com>
>Reply-To: Discussion of AM Radio <amradio at mailman.qth.net>
>To: "Bob Macklin" 
><macklinbob at msn.com>,<glowbugs at piobaire.mines.uidaho.edu>,"'Amradio 
>(E-mail)" <amradio at mailman.qth.net>
>Subject: [AMRadio] RE: GB> Antenna Tuner Wonderings
>Date: Tue, 14 Dec 2004 11:14:24 -0500
>
>Thanks for your reply.
>
>OK, Yes, I understand. Some of the rigs here are homebrew and the output 
>network designs are all over the lot. On the antenna side, there are 
>situations here like a vertical with a poor counterpoise that will have 25 
>or 30 ohms to match at some frequencies. Then there's the Windom, which 
>isn't resonant anywhere. IMHO, resonant antennas are convenient, but 
>certainly not necessary (thank God).
>
>73, Don Merz, N3RHT
>
>
>-----Original Message-----
>From: Bob Macklin [mailto:macklinbob at msn.com]
>Sent: Monday, December 13, 2004 5:56 PM
>To: Merz Donald S; glowbugs at piobaire.mines.uidaho.edu; 'Amradio (E-mail)
>Subject: Re: GB> Antenna Tuner Wonderings
>
>
>With BA unit wit Pi networks you don't need a TransMatch (they ARE NOT
>antenna tuners). Most will match anything between 50 and about 500 ohms. 
>One
>exception is the Heath DX-60. It is limited to 50 to 75 ohms becase of the
>built in LP filter.
>
>You need a resonant antenna for each band you want to work. Some could be
>multi band antennas.
>
>A TransMatch does not correct antenna problems. It hides them from the
>transmitter. The Pi network in the BA rigs is the same thing that was in
>older transmatches to connect link couples transmitters to coax lines.
>
>It is the solid state riceboxes that really need a transmatch.
>
>Bob Macklin
>K5MYJ/7
>Seattle, Wa.
>
>"REAL RADIOS GLOW IN THE DARK"
>
>
>
>----- Original Message -----
>From: "Merz Donald S" <merz.ds at mellon.com>
>To: <glowbugs at piobaire.mines.uidaho.edu>; "'Amradio (E-mail)"
><amradio at mailman.qth.net>
>Sent: Monday, December 13, 2004 2:23 PM
>Subject: GB> Antenna Tuner Wonderings
>
>
> > As most of you know, I am a long time BA collector and inexperienced
>operator. I am getting there. But it's a learning process <grin>.
> >
> > I have the shack structured (in the loosest sense of the word...) into a
>number of stations (20-25 with about 10 in actual operation). These mostly
>consist of a transmitter/receiver pair with T/R relay and RX muting. The
>stations are in the range of 40 to 250 watts max. I run these into your
>choice of 5 or 6 crappy, mostly non-resonant antennas with connections 
>being
>made through a home-made SO-239 "patch panel".
> >
> > Most of my interest is in AM operation on or near the supposed "AM
>windows" on 80, 40 and 20. I have some rigs that I never change bands on. 
>My
>operation is often xtal-controlled but I have VFOs on some of the rigs. 
>Most
>of these old BA transmitters are pi-net outputs.
> >
> > So here's the deal: I can tune any of these stations into a 52 ohm dummy
>load and set up the rig easily enough. Now I switch to one of my crappy
>antennas. And of course, it is nowhere near 52 ohms at the desired 
>operating
>frequency. If the mismatch isn't too bad, I can re-tune the rig's output
>network. If the mismatch is ugly, or if the output network is limited in
>range, then I can  "insert antenna tuner here" to get a match.
> >
> > After a while, laziness sets in. Why should I have an antenna tuner for
>each rig?--especially if I never change bands on that rig? Wouldn't it make
>more sense to dedicate an antenna tuner to each antenna? I can use my 
>little
>Palomar Tuner Tuner to match to pre-set each antenna to 52 ohms for each
>frequency of interest and mark each antenna tuner accordingly. Then I can
>simply load the rig up for 52 ohms into a dummy load, select an antenna, 
>set
>the antenna tuner to my previously-marked 52 ohm point for that frequency 
>on
>that antenna, patch the rig into the antenna tuner--and push-to-talk.
> >
> > Ok, sure, this setup put the antenna tuner over at the patch panel and 
>not
>on top of the rig. Pretty inconvenient. But hey, there's 20-25 stations to
>deal with here. I'm supposed to have 25 antenna tuners? OTOH, I have only 3
>antennas that are sloppily non-resonant enough to require a tuner at the
>frequencies I am interested in. So that's 25 tuners (okay, I'm
>exaggerating--it would probably be only 10-15 tuners because the other
>stations probably have adequate output networks) versus just 3.
> >
> > This trade-off seems worth it to me. But experience is in short supply
>here. So "pray tell me"** experienced ones, what am I missing? What is 
>there
>about this idea that is bad?
> >
> > Any thoughts appreciated.
> >
> > 73, Don Merz, N3RHT
> >
> > ** When Winston Churchill was named First Lord of the Admiralty in 1939,
>he was famous for firing off memos with questions to subordinates that 
>began
>"Pray tell me...". In the Royal Navy, these soon became known, obviously, 
>as
>"the Lord's prayers".
> >
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