Dick,
I've not read the AEA manual, but it should warn you about the method used
to measure able loss.
That loss method is dependent on cable Zo.
With connectors and relays in line, you will have impedance bumps that
upset the return loss readings. That can make the cable look lossier even
though it is NOT.
Such errors show up as a periodic variance in loss as frequency is changed.
That sounds exactly like what you have.
The most accurate way to measure loss will always be by reading power
applied and power delivered. The return loss method works fine, IF line Zo
is exactly right and there are no "bumps" in the line.
By the way, loss in a 259/SO-239 is nearly immeasurable at HF and lower
VHF.
73 Tom
> As you can see, the measurements for 80M, 15M and 10M are quite close to
the
> computed losses, and the differences could easily be accounted for by the
8
> PL-259's and one set of relay contacts in the run. But the measurements
for
> 40M and 20M are significantly higher than the computed values. The
antenna
> SWR curves, as measured from both the CIA HF and the transceiver are
normal.
> Does anyone know what might be causing the discrepancy? Could it be
> broadcast interference?
Don't you unhook the feedline from the antenna to measure loss? BC
interference is not a problem with no antenna, as long as the analyzer is
connected properly and the cable has proper shield connections.
73 Tom
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