[R-390] IF Modifications - Teledyne 3399

[Larry H]

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> 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 <r-390-bounces at mailman.qth.net> On
> Behalf Of gary.biasini at shaw.ca
> Sent: January 22, 2023 9:01 PM
> To: 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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