Rca q16e radio volume taper replacement wisdom needed

[smccaskill]

I am rebuilding an RCA Q16E tube radio chassis RC-561-C and need to replace the bad volume taper. It has a combination power switch and volume taper. The volume taper is a 2 meg volume taper with a 500K tap. I am not familiar with the 500K tap feature on a volume taper. Is there some way to simulate this feature with a standard 2 meg taper? It has a very simple circuit with 6SA7, 6SK7, 6SQ7, 6F6G and 5Y3G but its a nice multi-band radio. I may have to dismantle the old taper and try to move the wiper bar or something. I would prefer to replace it with a new one if I can, but they don't make this kind anymore, I don't think. Any help would be SO greatly appreciated! Stuart McCaskill

 

[peterh]

The 500k tap is most likley part of a "Loudness" circuit. It cannot be simulated without a tap.
As you also have a power switch in the volume pot you really need an exact sparepart
or you have to rebuild your unit.

If rebuilding is needed you might use an SSR instead of power switch, controlling
the SSR with any small-signal switch you have available on the front panel.
Providing you have a small battery ( 4.5V will do ) you can wire the switch so it will
energize the SSR with power from the battery until you have some other power
available that will continue to energize the SSR. That way your battery will last years and years.

 

[ferninando]

Ssr?

 

[peterh]

solid state relay
http://en.wikipedia.org/wiki/Solid-state_relay

A "relay" controlling 50A with 3-32V a few mA, opto-isolated and make/break in the zerocrossing.

 

[gadget73]

Try this guy, he may have exactly the right volume control:

http://www.oldradioparts.com/

Also, this gentleman has a lot of parts. No, its not the same guy

http://www.oldradioparts.net/


I wouldn't worry about the power switch. Its not that common that they burned out. I've got some that are pushing 90 years old and still working fine. Actually the only smoked power switch I have is on a late 50s Fisher. All of my others are original, many from the 20s-60s.