[NLRS] Transco relay

[John Oehlenschlager]

You might consider using a transfer relay rather than a regular relay.  It
is a 4 port device rather than a three port.  One port to the transceiver,
one to the antenna and two to the preamp.  In the de-energized position, the
transmitter is routed to the antenna and the preamp input and output are
shorted together.  In the energized position the preamplifier input is to
the antenna and the preamplifier output is routed to the transceiver.  It
could be used the other way but this ensures that a power failure or other
such uncommon occurrences don't eat the preamp.  Since the preamp I/O are
shorted together you get much more protection than just the contact
isolation.  Transfer relays are commonly used in the Radar, Electronic
Warfare and aviation communications which I have worked with over the years.

        John Oehlenschlager  K0JO