[R-390] CU-168 Coupler

[John KA1XC]

Woohoo Tony, it's your lucky day.
I was curious too so I went to the LOGSA site and typed in CU-168 into the
Pub Title Text box and hit search,
and out popped the TM 11-5985-212-15 Field  and Depot Maintenance Manual.

It's one of those classic designs that uses a lumped element delay line to
feed independent push-pull 12AU7 amps.
It has an input transformer for its front end and they are usually pretty
robust, so just treating it as a normal RX input should be sufficient to
protect it.  I remember an old post from Nolan Lee where he told of his
setup taking a lightning hit and toasting his multicoupler, but the RX's
connected to it were fine. Unlikely that a solid state multicoupler would
offer that kind of protection.

Don't forget to terminate the delay line output J203 if you're not using it
to feed something else.

http://www.logsa.army.mil/etms/find_etm.cfm

John
KA1XC


----- Original Message ----- 
From: "Tony Angerame" <tangerame@earthlink.net>
To: <r-390@mailman.qth.net>
Sent: Saturday, April 17, 2004 8:53 PM
Subject: [R-390] CU-168 Coupler


> The CU-168 coupler is in use by many R-390a owners so I hope this is not
> too far off topic. Question is: "Where can I get a schematic". The
> circuit is easy to reverse engineer but I just wanted to know what
> protection this device offered from excessive rf voltages at the antenna
> if any? I'd like to know this before I figure a way to add it in myself.
> i.e an extra set of relay contacts shorting the input when I key up.
>
>
> Tony WA6LZH (Aging Intercept Operator)
>
> R-390a Vietnam era Intercept Radio
> SP-600  Korean war to Vietnam era Intercept Radio
> BC-779/SP-210  WWII era Intercept Radio
> CU-168 Multicoupler   Listening to all of them at the same time!