Excellent. Thank you, Alan. Data for this particular measurement are very
difficult to find on the web -- of course it took an ex-HP guy to do it!
Times Microwave (a manufacturer of coaxial cable) says 0.01 dB per UHF
connector pair (PL-259-to-SO-239) at HF; I have seen other private measurements
that estimate 0.02 dB; and now this data from N1AL. I usually take the greater
of these, 0.02 dB, as a worst-case number. But Alan's measurements pretty much
show that the loss at HF is almost too small to measure-- even if he had
performed a full two-port cal.
Even so, you might be surprised to see how quickly it can add up. Beginning at
the transmitter output (or receiver input) it is not uncommon to find 20 or
more UHF connections in the path to the antenna. Using the 0.02 dB worst-case
figure, that's at least 0.4 dB, or 9% of your power. I wouldn't worry about
that but I know there are folks on here that would be bothered by that.
This, of course, is not counting loss in cables, filters, lightning arrestors,
power meters, bulkheads, switches, antenna tuners, baluns, amplifier
through-paths, transmission lines, etc. These can add another dB or more to the
total and far outweigh any loss in UHF connectors. If you want to minimize
losses, UHF connectors are the last thing you should worry about.
I encourage you to do an analysis to determine your system efficiency. I
recently did so and discovered that I have a worst-case loss (to the feedpoint
up at the antenna) of 1 dB, which is 21% of my power. Gone. Forever. Whoosh!
Al W6LX
_______________________________________________________
--------- Type N -------- ---------- UHF ----------
FREQ (MHz) TOTAL LOSS PER CONNECTOR TOTAL LOSS PER CONNECTOR
1.8 0 dB 0 dB 0 dB 0 dB
30 0 0 0 0
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