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Re: 2m uplink available on Wednesdays



Jim Jerzycke wrote:
> 
> Why can't you just run your rig in 'split' mode, and use a transfer
> relay with a sequencer to avoid blowing out your downconverter?

Well, you COULD, but:
  1) most people WON'T
  2) if you ever plan to use the radio to receive on 2 meters, at
     some point you will either have to remove or defeat the transfer
     relay, at which point you are once again vulnerable to forgetting
     to re-insert/re-enable the transfer relay, and in a moment of
     hurry, POOF goes the downconverter.

Another solution would be to have a pair of coax relays, one on each
side of the downconverter.  Whenever the downconverter is turned on,
it would switch the coax relays into circuit and disable VHF transmit,
(or enable the T/R bypass relay you mention).  And whenever the
downconverter is turned off, the coax relays switch the downconverter
out of circuit and bypass it completely, and then either re-enable
the VHF transmit circuit or bypass the T/R relay.  A little more
complicated arrangement, but somewhat more foolproof.

And I use the word foolproof with some reluctance.  There's an old
saying that goes, "You can't make anything foolproof because fools
are so ingenious."  I'm amazed at the stupid things that even very
smart and reasonable people do on occasion, when they just don't
pause to think things through carefully...

I will be interested to hear reports back from folks who try to
operate in mode V/S.  Maybe the shielding of the downconverter,
feedline, and 2M receiver will be sufficient to keep out "enough"
of the 2M transmit power.  Maybe the fact that many of the
downconverters have plenty of gain on the 2M side and actually
need attenuation before coming into the 2M receiver will help to
reduce desense.  Maybe the fact that someone running mode V/S with
a 2M IF on the S-band downlink needs two wholly separate radios to
do it in full-duplex mode will also help overcome the desense
problem.  Maybe the fact that some folks are running modified
surplus downconverters at 123 MHz instead of 144 MHz will help a
bit.  Or maybe none of the above will be enough.  The only way
to know for sure is to try it.  I certainly feel that a short test
period once a week is worth a try, and I applaud the Command Team
for being open to doing the experiment, even though I have no
plans to try the mode myself.

73 de KB0ZEV
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