"Dave Platt" wrote in message
...
In article ,
Douglas W. \"Popeye\" Frederick wrote:
But hhhhhere's a question for the braintrust:
I'm after a (mobile) VHF radio that's common to northern (i.e., the
Yukon,
and Northwest Territories) Canadian truckers- who don't monitor CB bands.
(info
http://forums.qrz.com/showthread.php?t=171741
I'm sure, as a sine wave challenged layman, that I can't use the same
antenna and coax as my CB?
In principle, you could combine the CB output (27 MHz) with the VHF
radio output (up above the 2-meter band) using a diplexer, and feed
the result down a single coax.
At the antenna end, you'd have a couple of choices. You can use
another diplexer to split out the HF and VHF signals, and feed them to
two separate antennas. Or, you might be able to find a single CB-type
antenna which is also capable of matching up well enough on these VHF
frequencies to work tolerably well.
The chances are very poor that a randomly-selected CB antenna would
give you a tolerable SWR on the 160-or-so-MHz VHF band... and if it
did, there's no telling what its vertical radiation pattern would look
like. An antenna intended for these two bands would probably have to
be custom designed - I can think of a couple of possible ways to do
it. Such a dualband antenna would almost certainly be a compromise
antenna on both bands - it wouldn't work as well as separate antennas
designed for best operation on a single band each.
Commercial HF/VHF diplexers run somewhere around $80, last time I
looked. You'd probably find it less expensive in the end to just run
a second coax and put up a second (VHF-only) whip antenna.
Thanks!
That's the kind of helpful and intelligent response I was looking for.
The radio would be for emergency communications anyway, to trucks in
the -immediate- vicinity.
The 4 "LADD" frequencies are used by the scale houses up there, as well.
--
Dave Platt AE6EO
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--
Popeye
"Best thing for him, really. His therapy
was going nowhere," -Hannibal Lector.
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