[R-390] R-290a modified IF sub-chassis

[Gary I. Biasini]

Good Day.  This is my first post as a member so I hope I don't run afoul of
any of the rules which I have carefully read.

 

I recently purchased what purports to be a Teledyne Systems R-390a Serial
number 2697.  I say "purports to be" because the various sub-chassis are as
follows:

 

RF sub-chassis - Capehart Corporation Order No. 21582-PC-61, Serial no. 585
Crystal Oscillator sub-chassis - Capehart Corporation Order No. 21582-PC-61,
Serial no. 626 IF sub-chassis - Capehart Corporation Order No. 21582-PC-61,
Serial no. 808 Power Supply sub-chassis - Capehart Corporation Order No.
21582-PC-61-A1-A1, Serial no. 713 Audio sub-chassis - Teledyne Systems Corp.
Order No. 37856-PC-63 PTO - Progressitron Corp. Type 798 Serial No. 8703

 

I purchased the receiver from William Pearl, a formerly licensed ham
operator living in the Long Beach, CA area.  I happened to be in the Phoenix
AZ area at the time I agreed to purchase it so my wife and I drove out to
meet Bill and pick up the receiver in person.

 

Bill advised that he obtained the receiver more than 30 years ago from
another ham and, after children arrived, it sat in his garage unused for 30
years.  He said he turned it on prior to selling it and, with a short wire
antenna, it picked up some stations.

 

I have carefully read the admonitions against turning on the receiver until
a few things are checked out and replaced like C553 and, have ordered
replacement caps for all of the paper capacitors and others that are
recommended and will hopefully find time to replace them in the next few
months.  In the meantime, in looking at the receiver, it appears that a
number of modifications were made, some of which I cannot seem to find in
the archives.

 

This first message will discuss the modifications that I have noted on the
IF sub-chassis.  In particular, I note a 1,000 uF 25VDC electrolytic
capacitor and an unknown device with 8 leads exiting the body.  I assume
that this is some sort of AGC modification.   Any comments would be welcome
and any questions will be answered to my ability.

 

The URLs to pictures of the modified module are below:

 

https://1drv.ms/i/s!AhXaYQRsUlJ0gbU1YrERkfud0axItQ

 

https://1drv.ms/i/s!AhXaYQRsUlJ0gbU5K1--TAXeKe4ZgQ

 

Thank you in advance for any comments.

 

Gary Biasini