[R-390] Using Break-In

[rbethman]

Ed,

When these were built, QSK wasn't even a thought.  Break In grounds the 
antenna input to the circuitry.  You still need an antenna relay to keep 
the transmitter from blasting into the R-390A.

I use a Johnson TR Switch, turn on break in, and put a monitor scope on 
the 455 Kc IF BNC on the back of the IF section.

It still gets enough RF to show precisely what my transmit signal looks 
like.

Bob - N0DGN

Ed G wrote:
> Hi Folks,
>      From reading about the break-in feature of the 390A, I *think* it works
> like "receiver muting" does on more modern receivers, but I wanted to get
> some other opinions. If I leave the front panel break-in switch off, I
> believe the 390 just keeps receiving (with no connections to TB103 pin 9),
> correct?  If I turn the front panel break-in switch on, what have I enabled
> circuit-wise?  Can I then ground the rear panel TB103 pin 9 and have the
> receiver mute, or does the receiver then just ground the antenna inputs, but
> allow me to hear the transmitter?
>      I guess the term "break-in" is slightly confusing, as I doubt this is
> really full QSK.
> --Ed G--
>   

-- 
Bob - NØDGN