|[AMRadio] Open Wire - was AMRadio Digest, Vol 46, Issue 24|
km1h at jeremy.mv.com
Wed Nov 14 12:41:32 EST 2007
----- Original Message -----
From: "Robert Nickels" <W9RAN at oneradio.net>
To: "Discussion of AM Radio in the Amateur Service"
<amradio at mailman.qth.net>
Sent: Wednesday, November 14, 2007 11:10 AM
Subject: Re: [AMRadio] Open Wire - was AMRadio Digest, Vol 46, Issue 24
> Ben Dover wrote:
>> I personally love the stuff. Coax has it's place, but often it's not the
>> best solution to the problem.
> I've always used coax, but wanted to give open wire a try, and so far I'm
> very pleased with it. But let's talk tuners for a minute, assuming that
> we're not directly coupling to a balanced plate tank. I've been running
> 1500 watts PEP into a Heathkit SA-2060 with it's 4:1 balun without
> incident, but I've heard all the stories about core saturation, etc.
> How much advantage would a "real" balanced line tuner (e.g. a link-coupled
> tuner or Johnson Matchbox) have? Then antenna by the way is 130 ft,
> center fed, and primarily used on 75 meters.
Bob, the KW Matchbox has a limited range on 80M and is reportedly quite
You can upgrade your Heath (or is that Heat) tuner with a stack of T400A-2
cores, some #12 or 10 teflon wire and HV tape. Calculate the turns from the
Amidon or Micrometals site specifically for 3.8 MHz, it will maintain
excellent balance 160-20 as well as less loss.
> Also, having read comments by Cebik and others - any thoughts on
> homebrewing high-power balanced tuners?
Other than trying to find the components that can handle the power go for
it. The design should be High C to minimize loss. I believe there was a
built to order commercial tuner available that was pricey but built to
perform. Id probably go for one of those big edge wound fixed coils and a
big switch, or a pair if you cant find a 2 section one. I wouldnt trust a
rotary over such a wide range of unknowns.
> Thanks and 73,
> Bob W9RAN
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