In a message dated 2/11/04 1:33:09 PM Eastern Standard Time,
mark@microenh.com writes:
>>I didn't realize that there were 3 filters in the chain. I only thought that
there were the two at 6 MHz and 9 MHz. Was the 600 Hz roofing filter a
hardware change? I assume that this dedicates the radio to narrowband modes
as a 600 Hz roofing filter would be too narrow for voice.<<
There are actually 4 filters in the chain. The first one is the monolithic
filter Y1 that is 15 kHz wide and that is actually the roofing filter. This one
is hard wired in and this one, for non FM types, could be replaced by narrower
filter. Not much room around, but it is not impossible
to replace it with narrower one. If it was placed on the socket, it would
have given us nice option of tailoring the rig and perhaps beating the rest of
the rigs in specs.
Then we go to Y2 which is 9 MHz 2.4 kHz wide standard SSB filter and it is
socketed. The optional 9 MHz filter is in series with Y2. This is what allows
easy cascading of say 600 Hz filters in 9 MHz IF.
Then going through another conversion there is the 4 position 6 MHz filter
bank. Those are the third filters in the plug-in chain.
I "dedicate" the Omni before the contest to CW and place 1 kHz or 600 Hz
filter in Y2, 500 in 9 MHz optional position, and selection from 1 kHz, 500,
250
and 125 in 6MHz bank, either of TT or Inrad breed.
There is plenty of room inside TT radios, so filters could be wired with
switching arrangement. Or just plug those race horses that you need for the
upcoming race (less blow-by).
73 Yuri, K3BU
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