RG-62

[Bob Bruner WB4TAJ]

RG-62 cable is not an exotic product.  It's a commonly used coaxial cable,
applied to LANs, car radio antennas, etc. It's in the Belden catalog and
almost all large distributors sell it. There is no need to seek esoteric
sources, or deal with strangers in alleys to get it.  You can probably "get
away with" using other cable.  The advantage of RG-62 is that it is a low
loss, 91 ohm cable.  The 91 ohm impedance is obtained by using a smaller
center conductor and a partial air dielectric, which gives it a lower
capacitance per foot.  This results in reduced losses, and more importantly,
less loading and interaction on the tuned circuits inside the radio.  If you
used RG-58, let's say, you might have to retune the SB-3nn/SB-4nn combo to
compensate for the different capacitance of the cable.  You might find that
you slightly less drive on the HFO at the transmitter end of the cable on
some bands.  But your radio would still work.  The BFO and LMO operate at
such low frequencies, that there would be little real effect.  two feet of
cable is too short for SWR to be much of a factor on these lines.  Collins
used RG-58C in the same application and somehow they manage to get S-lines on
the air. In fact, their cables are 4 feet long. In theoretical terms, the
RG-62 would be "best," but don't let your radio sit around unused because you
don't have six feet of it.  If you really feel compelled to use that "stock
cable" you don't have to search the Internet for it, it's commonly available.
 In fact, if you work where there is a computer network you may find they
have a bunch of it that they will give you.  Most coaxial Ethernet is cabled
with RG-58, but some specialty LANs use RG-62.

73,
Bob Bruner
WB4TAJ/9

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