John,
I don't have a BC tx, but my rig would compare in regard tuner
requirements. I home brewed a link coupled tuner, and think that's
the only way to go for a big power AM tuner to open feed line. I got
a very large rf coil with rotating link off epay several years ago,
along with a split stator air variable of about 250pf per section and
probably 7+kv rating. Very simple to build if you can find or make
the parts. I've tested the tuner into a makeshift load (dummy) of
about 200 ohms with almost 3KW and the coil did nothing but get a
little warm after a minute or so.
Brian / w5ami
On 12/7/06, John Lawson <[EMAIL PROTECTED]> wrote:
I'll be dragging an RCA BTA-1MX broadcast transmitter back to KB6SCO
next weekend. (Was going to try this weekend, but schedules and weather
prevent...)
And I'll be primarily QRV (QRO!) on the AM Window of 80M.
I have a 480' square loop of good 14ga copperclad wire strung around the
fence at the rear of my property - the feedline is 450-ohm ladderline at
the point closest to the shack. It's 5' off the ground on average, one leg
of about 50 feet is at 7'. It's a quasi-NVIS, or "RF Fountain" if you
will.
And before the "Why don't you..." comments even get started - I can't do
anything else in the QTH I'm in now - the Antenna Configuration will not
change until I move...
Currently I use an Ameritron ATR-15 tuner, using the balanced outputs
(through an MFJ crossed-needle balanced ammeter) and driven by my faithful
Valiant. On any part of 80, I can tune 'er down to 1.1:1 - and have many
successful QSOs with good signal reports - so the System appears to be
working.
NOW, THEREFORE: I would like to use the RCA and yet do as little damage
as possible to the Rig, the Fence, and my Nieghborhood Relations. I have
a plan in mind to build a fixed-bandwidth tuner installed at the feedpoint
of the Loop - and just run good coax out to it - from where the RCA will
be situated this is about 30'. I also have a dual-rolling-inductor tuner
which was built by someone who makes them 'to order' - still pretty much a
homebrew job - it is supposed to handle 2KW easily - and has a coax
solenoid for a balun.
What are you QRO-types' experiences with tuners, antennae, and higher
powers? Especially if anyone is running a b'cast rig thru a homebrew or
commercial (or military?) tuner - I'd be curious as to pros/cons -
likes/dislikes - horror stories, etc.
Cheers and Best of the Season
John
KB6SCO
DM09fg
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