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Old April 8th 07, 01:15 AM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Coaxial Cable considerations for HF

jawod wrote in news:68ca4$46182214$d066b697$10313
@FUSE.NET:

Having re-entered ham radio after a 30 year hiatus, I would like to ask
about RG/8U versus other cable types for use in a simple dipole or G5RV
installation with 100W max. transmitter output. In the "good old

days"
Low loss "8U" was sort of the standard. There are some newer cable
designations now.

Is there a better "standard" cable for the above use than RG/8U
(specifically Belden 9913 low loss)?


My article at http://www.vk1od.net/G5RV/index.htm models the efficiency
of a number of feed options for G5RV, it may provide the answer to your
questions.

Re a "simple dipole" (if that means a half wave dipole, a one band
antenna), I currently use an inverted V dipole on 40m. It is shortened to
cause VSWR=1.5 on RG6 feedline (75 ohm), and the RG6 feedline is of
length (21m) that transforms the feedpoint impedance to nominal 50 ohms
to connect directly to the amplifier (AL-811H) (VSWR1.1 at band centre).
The RG6 has a heap of suppression sleeves threaded over the load end as a
W2DU style balun. Total feedline + balun loss is 0.4dB. There are simple
solutions out there, and feedline doesn't come cheaper than RG6 at US
$0.20/m here in Oz (but you need to be selective in choosing RG6 for this
purpose).

Owen