In article ,
west wrote:
Originally I requested a source for various length of cables with SMA Male
on one end to plug into a HT (Kenwood TH-F6A) and the other end a PL-259.
Lengthy and comprehensive treads soon made me realize that the PL-259 would
be ill advised especially at UHF & higher. So I found some ready made cables
with SMA and N connectors. The only problem (if it's really a problem) is
those skinny cables they come in. Some claim that they are 50 ohms, another
RG-174.
RG-174 is a 50-ohm cable, just over 1/10" in diameter. It's a decent
choice for HT-to-whatever pigtails, at long as the length isn't so
great that losses become unacceptable.
I don't know the other types. Do you think it will be alright to use
those narrow cables from my HT to an amplifier to my monitoring meter and
then use regular RG 8 to the base antenna?
Almost certainly for short lengths. I wouldn't use it for long runs.
The attenuation per 100' of RG-174 is around 13 dB at 146 MHz, and
about twice that at 440. Thus, at 440, 10' of the cable would lose
you around 2.5 dB, or less than 1/2 of an S-unit at the conventional
calibration. This loss would occur for both transmission and reception.
There are other cables of this size which are less lossy - LMR-100A
has approximately half as much signal loss per foot.
Both RG-174 and LMR-100A have solid center conductors, and might not
stand up to a very large number of flexing cycles. A cable of similar
size with a multistrand center conductor might live longer.
Will those skinny cables present
some kind of mismatch.
Not unless the manufacture is seriously botched (e.g. cable not
soldered to connector correctly). They're the same impedance as RG-8,
but are a lot more lossy.
You know it's almost impossible to solder a SMA
connector to an RG 8. Thoughts, please? Thank you.
Go for it. A pigtail of anywhere from 18" to a few feet should act as
a perfectly acceptable strain-relief for your HT's SMA connector, and
even at 440 its loss should be low enough that you'd be unlikely to
notice it.
--
Dave Platt AE6EO
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