Can anyone tell me the approximate loss for a PL-259 connector at 28 MHz?
Also, does anyone know the approximate loss at 28 MHz for antenna switching
relays like the ones used in the Ameritron RCV-8?
Right now, I have 8 connectors between the amp and each of my antennas,
which includes junctions at a couple of Polyphaser lightning protectors and
a remote antenna switch. The switch adds one set of relay contacts. My AEA
CIA HF analyst shows total loss for the 260' cable run, including connectors
and the antenna switch, as 2.2 dB at 28.250 MHz, which is only .2 dB higher
than manufacturer's spec of 2.0 dB for a cable of that length (it's Times
Microwave LMR400UF and I got their loss figure from the attenuation
calculator on their web page.) That seems pretty reasonable, and would
indicate something on the order of .025 dB loss per junction (averaging the
connectors and relay contacts.)
I ask because I'm planning to install more PL-259's and more relays for
automatic two-radio switching and bandpass filtering, and am trying to
anticipate the additional losses. With some rearrangement of the existing
configuration, the basic switching adds 2 connectors, bandpass filtering
adds 2 connectors and switching for amp sharing adds 3 more connectors, for
a total of 15. (The latter is an experiment: sharing an 87A between two
radios with automatic switching, the idea being to take advantage of the 87A
automatic QSY.) The switches will add four more sets of relay contacts
(replacing the Ameritron with TopTen A/B and 1-of-6 switches.) If the above
loss-per-junction figure is right, I'm looking at an increased loss of about
.3 dB. Sound right?
73, Dick, WC1M
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