[R-390] Dead R-390A Update

[Bob Camp]

Hi

The R-390- either one was built in the era of the VTVM. Most of the 
voltage checks on the radio are based on a high impedance measuring 
device. A VOM will give you different readings on *some* of the test 
points. VTVM's are not a real popular item any more. You see them come 
up on the auction sites or at flea markets for less than the price of a 
family lunch  at Burger King. They also do not take up a lot of room in 
storage while you are not using them. If you don't already have one I 
think it might be a good idea to get one. They make the process you are 
diving into a whole lot easier.

On a lighter note - this is a perfect excuse to buy a second working 
radio. Then you could swap modules back and forth to find the problem. 
The purchase of the $500 radio would save you the $10 or $15 on the 
VTVM.

Of course once you found the problem module in the radio, you would 
need a replacement. Now you need to buy a parts radio to swap in the 
module from. Now with three radios the investment in a signal generator 
makes sense. So does stocking a full set of tubes.

This is more or less a disease ....

	Take Care!

		Bob Camp
		KB8TQ



On Feb 20, 2005, at 6:05 PM, Bill Keller wrote:

> The situation with this radio is getting more confusing.  I went 
> through it and checked every tube substituting one tube at a time and 
> found nothing - ended up leaving the old tubes in.  I also checked all 
> connections and replaced the can holding Y201 & Y203 - didn't help, so 
> left original can and crystals in.  So, nothing was actually replaced, 
> but somewhere during the time I was doing the checking, the radio 
> gradually went from totally dead to barely working.  The strongest 
> signals will now come in barely audible with the gain all the way up 
> but still not strong enough to copy.  If I turn the limiter on, they 
> get slightly stronger.  And if I turn on the BFO, they get even a 
> little bit stronger, but still not strong enough to even hear unless 
> the gain is turned all the way up.  I can barely tell that signals are 
> there, and that includes nearby broadcast stations.  Nothing, of 
> course, is anywhere near strong enough to even budge the S meter.  
> This radio was totally restored by Miltronics a few years back and is 
> exceptionally clean, so I know that it's well worth fixing if I ever 
> get smart enough to figure out what's wrong with it.  And if I have 
> the time and space to take it apart to work on it.
> Bill K.
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