[R-390] R-390a question (Tony Casorso)

[ToddRoberts2001 at aol.com]

In a message dated 2/13/2008 4:07:21 P.M.  Eastern Standard Time, 
SHELLY199 at aol.com writes:
If you get similar readings  you have the Lankford mod in the IF deck.   Just 
one word of  caution-watch the 1N4148 diodes.  Switching the AGC time  
constant  
will deteriorate one of the diodes because of a fairly high voltage   
transient during the switch operation.  I once measured it because I  got  
tired of 
changing diodes but don’t remember the transient voltage  value.   To 
evaluate the 
diodes you have to unsolder one end  because of the parallel ckt  
resistances. 
I ended up with a 1N914 and a  1N5060.    If  you notice distortion on a very 
strong  broadcast station check the  diodes.

Bye
Rich  


Thanks for the warning about blowing the 1N4148 diodes. It would be  
disappointing to take the time and trouble of installing the Lankford  mod  just to 
have the 1N4148 diodes deteriorate and give poor results.
 
73 Todd WD4NGG



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