[AMRadio] High-power tuners

John Lawson jpl15 at panix.com
Thu Dec 7 14:24:39 EST 2006

   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 

   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 

   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 

   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


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