[R-390] Local & Line gain potentiometers R390/A

[Thomas Frobase]

I have NOS 2W linier 2.5K pots here if anyone needs them. ... tom, N3LLL 

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Charles Steinmetz
Sent: Monday, December 30, 2013 3:12 PM
To: 390 list
Subject: Re: [R-390] Local & Line gain potentiometers R390/A

Craig wrote:

>The question is what: What is the translation for RV4ATSA252D? Panel 
>mount is a yes, 2W is a yes, ¼ X 7/8 inch shaft is a yes. Taper????? 
>I’ll also dare to ask what is today’s replacement?

"252D" means 2.5k ohms, log taper.  Is the shaft really 7/8", or is it 5/8"?
(If it really is 7/8", check to see where the setscrew divot is on the shaft
-- if it is farther from the end than 1/4", a 5/8 will work in its place.)

I believe RV4 and the commercial equivalent, the "Series K," are still
available.  You might try State Electronics or ETI Systems.  Digi-Key has
RV4 pots, but not 2.5k log taper.

The pots in a 390A are hot-molded carbon, but you may also be able to get
conductive plastic.

If you don't care about originality, any 2.5k log pot should work fine.
Actually, any log pot from 2k to 10k should work fine.  And there is no need
for a 2W rating -- 1/4W is plenty.

This 5k audio taper Alpha part ($1.50) looks like it might have a form
factor that will work:
<http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV16AF-20-15S1-C5K/?qs=sGA
EpiMZZMtC25l1F4XBUxcT8FFa2pT4Cm7Y%252b7ehOxI%3d>

I'm sure other suppliers have similar parts with appropriate form factors.

Best regards,

Charles



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