[ARC5] ATD/ARB on the air

[w7qho]

On Oct 6, 2008, at 7:55:25 PM, Meir-WF2U <wf2u at ws19ops.com> wrote:
Just for reference, I had a 100 pf  “doorknob” capacitor which I used initially in series with the antenna output of the ATD into the 50 ohm system. I managed to get around 25 W out of it, running out of tuning range on the ATD output tuning controls. With nothing at all between the ATD and the 50 ohm power meter (just to illustrate the large mismatch), maximum output I could get was 6 W

Hmmm...  I used a series cap and did better than that. Larger than 100pf but I don't remember how much.   Will have to dig out the rig and take a look.  Found a single value that worked FB on 75 and 40M and mounted it inside the cabinet.

The ATD  antenna circuit in the 3000 - 9050 kc TU is the familiar link off the PA tank to a variable inductance consisting of a variometer and a couple of additional coils with a bunch of taps instead of the more usual roller coil.  Also has an internal series cap that can be switched in  and out but only 40 pf, too small for 50 ohms on 75/80M.
--
Dennis D.  W7QHO
Glendale, CA
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