The Drake TR-4 came with 2.1 kHz filters.? I replaced them in mine with the aftermarket Inrad 2.5kHz filters.
Not only do I get much better reports on the air but the receive fidelity is a LOT easier to listen to!
I get great audio reports with my HT-32B.? I think it's got a 3kHz filter in it?
I couldn't find the filter specs in the SR-400 manual.? I guess they really don't say what the BW? is. but it would seem to be somewhere around 2.3-2.5 kHz based on the shift in the carrier frequencies?? I guess the only way to know for sure would be to "sweep" it.
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73/Rick
W4XA
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Rick W7IMM