[R-390] RF IMD Problem SOLVED!

[Joe Foley]

> NEXT, out of desperation I changed the RF amplifier,
> 6DC6 tube with one
> borrowed from Dons Receiver.  EUREKA!!! IMD totally
> gone AND the S meter
> moved from 80dB to fully pegged on my local station
> (as other R-390A's
> have done in the past)           
> 
> What I DON'T understand is this.  These two tubes
> checked IDENTICALLY in
> the B& K emission tester, both checked IDENTICALLY
> for gain in my
> receiver at 21MHz.  Neither test shorted or gassy! 
> RF GAIN CONTROL had
> no affect on the IMD.  What really messed up my
> thinking was that since
> the RF gain control didn't affect the IMD the RF
> amplifier must NOT be
> the culprit.  
> 
> YOUR THOUGHTS ???
+++++++++
Phil,

Do you have a tube tester that has headphone jacks on
either side of the SHORTS light?  Like a TV-7 or
TV-10?

I'd sure like to know if that tube SOUNDS like it has
problems, especially when tapped with your finger at
each SHORTS setting.  Where's one of those little
rubber hammers when you need one?  How did it perform
under the LIFE test?

We have to find a way to make that problem show up on
a tester.

Joe

__________________________________________________
Do You Yahoo!?
Yahoo! Finance - Get real-time stock quotes
http://finance.yahoo.com