[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 
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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