[R-390] IF Modifications - Teledyne 3399

[gary.biasini at shaw.ca]

Larry, and previously, Renee, 

 

Thanks for your comments.  I reviewed the drawing again against the wiring in the module and realized that I had missed a number of items.  A revised schematic, hopefully complete this time, is attached.

 

Regards,

 

From: Larry H <larry41gm at gmail.com> 
Sent: January 25, 2023 12:24 AM
To: gary.biasini at shaw.ca
Cc: R-390 at mailman.qth.net
Subject: Re: [R-390] IF Modifications - Teledyne 3399

 

Hi Gary, It looks like it converts V509A to an  AGC amp and removes V506A from the AGC time constant circuit.  But, the schematic still has some deficiencies to make it work.  V509A pins 1 and 2 need to be separated and pin 2 needs a resistor to set bias.  V506A still needs B+ to it's plate for the meter to work.

 

Regards, Larry

 

On Mon, Jan 23, 2023 at 9:35 AM <gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> > wrote:

Sorry folks,  I neglected to add the break in the C547 connection and the
addition of the new C547 connection.  Attached is a corrected PDF schematic.

Regards,

-----Original Message-----
From: r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net>  <r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net> > On
Behalf Of gary.biasini at shaw.ca <mailto:gary.biasini at shaw.ca> 
Sent: January 22, 2023 9:01 PM
To: R-390 at mailman.qth.net <mailto:R-390 at mailman.qth.net> 
Subject: [R-390] IF Modifications - Teledyne 3399

Good evening,



After some procrastination, I finally traced all the modifications that I
could see on the IF sub-chassis of one of my R-390a receivers.  I attach a
marked up schematic showing the changes.  This radio was in the worst shape
of the R-390a radios I have had and I have spent much time bringing it back
into shape.



Unfortunately, I cannot advise what effect these modifications appear to
have (they look like SSB and AGC modifications) since I cannot get the radio
to operate.  I had to stop troubleshooting as I blew all the 1/8 amp fuses
that I had and am waiting for some to arrive.





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