My ungrounded Pegasus / 706 mike combo suffered from RF gobbledygook (to
use tech jargon) until I attached a 1/4 wavelength single wire radial
for each band of operation to the rig ground post. I also use a current
balun on the rig end of of the coax running to my antenna selection
switch. For that, I employ the DIY approach offered by Palomar Engineers
(http://www.palomar-engineers.com/Balun_Kits/balun_kits.html). I use
these devices in the antennas I build (www.aerialacts.com), too.
So-called line isolators from Radio Works (www.radioworks.com) may be
useful, as well -- though I've never tried them.
An unexpected avenue of RF incursion into my trusty old Drake TR-7 (a
wonderul radio!) was a PTT footswitch. Thnking myself a shrewd bargain
hunter, I bought a footswitch designed for musical keyboard use from
Radio Shack (when will I learn?) for about seven bucks. Heh, heh -- I
thought I had put one over on ole Bob Heil, who wanted an exhorbitant 40
dollars for his switch. (Isn't it curious how we'll spend thousands of
dollars on equipment, yet balk at dropping a few more bucks for
accessories?).
Guess what? I now own the Heil switch. It's far better in every way
(including shielding) and well worth the price. And -- no more RF problems.
Now -- my question. My shack doubles as a broadcast voiceover
production studio. I'd like to run the audio chain (studio mike,
preamp, EQ, compressor/limiter) ahead of my Pegasus. I did this with my
old Collins 32V-2 -- using a Lo-Z to Hi-Z matching transformer -- with
much success, but am having trouble doing the same with the Ten Tec.
I'm getting distortion that sounds like that caused by an impedance
mismatch whether the matching transformer's in line or not. Of course,
I could be wrong about the source of the problem.
At any rate, what is the microphone input impedance of the Pegasus? Is
it balanced or unbalanced? The usual amateur radio approach is high
impedance unbalanced. I'm hoping that's not so with the Pegasus.
Many thanks and 73,
Craig
W3CRR
|