There IS isolation IF and only IF you throw the RX/TRX switch on the
back panel that causes the isolation. If you leave that switch
connected, transmitter RF may show on the receiver input jack. Though
there's supposed to be PIN diode isolation even then.
Virtually NO receiver has an output for a second receiver. You can run
two receivers on one antenna with a simple power splitter, such as an HF
versions of a cable or TV two way splitter, looses 3 dB (and a hair)
which isn't usually a problem at HF. Most receivers tolerate being
connected with their inputs in parallel. Works better after a low gain
preamp. There have been commercial signal splitters for a gaggle of
receivers, often used on military ships. There was a relatively fancy
splitter in QEX using ferrite cores and a couple MAV11 MMICs.
You can build one with a preamp stage, followed by as many
cathode/emitter/source followers with their high input impedance to
drive each receiver. If there's enough gain in the preamp (a few dB more
than the loss in a splitter) you can use a resistive two way splitter
consisting of three 16 ohm resistors in a star connection. One resistor
to the input, one each resistor to the isolated output.
According to MY Corsair II manual, there's two diodes switched off by
removing the R voltage from the LFP-TR board, then the T voltage causes
a transistor to short the receiver input for further isolation. Getting
100 watts to the receiver input with or without the RX/TRX switch in the
RX position, means putting 100 watts of RF on the internal receiver
input. Which should be frying the internal receiver input via the low
level driver board.
Looking through the circuits, a second receiver on the auxiliary
receiver jack should receive just fine with the RX/TRX switch in the
closed position and neither that receiver nor the Corsair II receiver
should receive excess power from transmitting with the Corsair II.
Blowing a Beverage transformer would indicate failures in Corsair
circuits.
73, Jerry, K0CQ
--
Entire content copyright Dr. Gerald N. Johnson. Reproduction by
permission only.
|