[1000mp] RX Ant Out

[Mike Gilmer, N2MG]

The RX IN/RX OUT jacks should be of little mystery to most of us - they have
been on high-end radios for many years.  My ca. 1988 TS940 has them, as well
as all the (older) TS930 models I have seen.  On those radios, they are
buried on one of those dang DIN sockets, however. When the TS850 came out
and didn't even offer the signal on a DIN, much complaining was heard.  But
that's Kenwood...

If I remember any of my receiver circuits,  that small coil/resistor sounds
like a simple static-drain circuit, basically there to SLOWLY bleed off any
charge/voltage build-up that can occur on antennas that are not DC-grounded.
Since the charge never builds up very high (thanks to the circuit) the
circuit does not need to be very robust.  I don't think it'd ever function
as a "surge" protector, however.  A close-by lightning hit, or high-power RF
would surely be capable of destroying it.  And since the circuit has no
series (with the antenna) components to act like a fuse, once zapped it
would offer no further "protection".

73 Mike N2MG

> I forget whether Barry has an MP or a Mark 5.  The function of the RX
> IN/OUT jacks is addressed on page 3 of the Mark 5 technical overview,
which
> confirms what everyone's saying, that it provides a place where various
> preamps, filters, etc. can be placed in the circuit from the transmit
> antenna to the receiver.
>
> It appears that RL-1002 in the Mark 5 opens the RX input line to protect
> the receiver from RF coming in on a separate receive antenna when the
> transceiver itself is transmitting.  The overview also says that the Mark
5
> incorporates a surge suppressor on the RX antenna circuit -- looking at
the
> schematic, it appears that there's a small inductor in series with a
> 100-ohm resistor to ground which presumably does this job.  It would be
> interesting to know from someone more technically qualified than I am
> whether this surge suppressor affords any useful protection for the front
> end from strong signals originating in another transmitter, for example in
> an SO2R setup.