Regrettably I am resigned to never having stacked monobanders on this
suburban lot. I have now started investigating the idea of using a
triplexor and associated bandpass filters as a way of getting an SO2R
antenna system operational utilizing the same 5 band yagi. Currently I am
using a ground mounted vertical (during the winter only) as the second
antenna.
The common application recommendations are to use one of the 2x6 or 2x8
switches to direct the 20/15/10m signals from either transceiver through the
matching BPF and into one input of the triplexor. I am seeing band to band
isolation figures of the filter/triplexor combos in the 85-100 dB
Unfortunately the 2xn switches appear to have radio A to radio B isolation
values in the 70 dB range.
Would this multiport switch isolation not be the limiting factor? Two 1 kw
transmitters will still place -10 dBm signals at the input of the other
radio.
How critical is it that the unselected bands be terminated in 50 ohm? I see
that many of the 2xn switches ground the unselected ports and this would
effectively put a short on the unused BPS filter input.
Would a second set of low power BPFs installed between the radio and power
amplifier be effective in removing another 30-40 dB of offending signals.
This comes at the expense of another dB or so of insertion loss.
Does anyone have any real-world practical experience using two - 1kw radios
triplexor/filter/switches.
Lessons learned are much appreciated.
Ed VE4VT
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