[R-390] nos pots

[Tim Shoppa]

> I need pots for a couple of 390-A's. Mouser does not have them.
Neither 
does AES.
> I am looking for the good 2 watt  pots that cam with the radios. Any
ideas?

Which pot? 500K limiter, 5K RF gain, 2.5K line gain and local gain
audio?

I have had good luck taking 5K audio taper pots, putting 5K resistors
in parallel to maintain the correct cathode load on the V601B cathode
follower, and using them in the line and local gain positions. I don't
think there's anything magical about the 2W rating there. The input
impedance to the next stage is 470K so there's nothing magical about
the exact resistance rating either.

Last time I checked the 2.5K audio taper pots were still current parts
in the Allen-Bradley catalog, just not standard stocked things at Mouser
Digikey et al.

Tim.