[R-390] Collins 51J-4 Connectors

[Barry Hauser]

> Hello from Vienna !

Hello from Long Island Kurt!
>
> My Collins 51J-4 (Ser. No. 2954) has 3 connectors on the rear panel that I
> cannot find on a picture in the manual I have.

Uh-oh!  Professional looking, yet undocumented.  Might still be classified.
Turn encryption on.

>
> The green is named "Diode Load" , the white "AGC" . Whats the use for the
> diode load and especially I would like to know if these are original (they
> look original and also the printing on the backside for these 2
connectors.
> They are situated on the right side of the rear panel left and right of
the
> ZF Out.

They look like either pin jacks or banana jacks.  Are they?  Could be for
ease in testing/alignment.  The diode load would have the same use as on the
R-390(x)'s and that's familiar -- like the front mounted diode load jacks
that appear on some R-390A's.  The AGC jack may also be for ease in
adjustment/calibration, unless this unit was modified or special order for
diversity use or something.  Are there any additional markings, tags, etc.
or a suffix letter on the serial number?  Might just be a very professional
modification. Could the lettering be dry transfer.  That usually doesn't
hold up unless coated with something.

>
> On the left side of the rear panel there is a (for me) unknown connector.
It
> is an old 75 Ohm connector which I saw in use for some video equipment
years
> ago at a TV station. I don't know what this connictor is used for.

Looks vaguely familiar but it's been a while.  Did you trace the
connector -- probably a length of coax going somewhere, possibly jumpered
over to the terminal block just to provide a better, fully shielded
alternative.  If that's a "studio pro" type thing, perhaps this rx was
prepared for use in broadcast work -- newsroom monitoring, diversity for a
relay station, etc.
>
> Can someone of you give me some help and look for the pictures at:
> http://members.chello.at/kurt.brandstetter/File/PIC1.jpg and
> http://members.chello.at/kurt.brandstetter/File/PIC2.jpg and help me to
> identify these connectors and give me some information if they are
original

I also noticed the SO-239 -- I don't think these were original to the
51J-3/4, R-388/A, etc. were they?

>
Might also be a special "cold war" model.  Don't mind me.  It's just when I
see "Hello from Vienna" I hear a zither playing in the background ....
ding-da-ding-da-ding ... da ding    .... ding-da-ding-da-ding ... da ding.
(Third Man Theme ;-)

I would close with something like "hope this helps", but, alas, I've been of
no help at all ....
       ..... ding-da-ding-da-ding ... da ding <sigh>

Barry