I have the 73 MHz roofing filter in my FT1000D and like it a lot since I
have another ham 3 blocks from me that also operates HF. It is still not a
cure all but knocks him down quite a bit where I can still work stations
while listening to his low level signal. (His signal is strong enough that
it gets into the 455 KHz IF so no matter where you tune you always here
him. Before the mod, the receiver just went dead when he would transmit.)
As far as the 455 KHz, 125 Hz filter goes, I tried one on 160 and it was
impossible to hear anything because the ringing was very bad. I assume it
was the noise ringing because of the non-linear group delay of the filter.
So I returned it to IR and settled for a 250 Hz. It still rings but on a
few occasions it works well. My thought now is to get IR to design a
Gaussian or Chebyshev Phase Error filter with a flat group delay to get
away from the ringing. The shape factor would not be as good but at least
the filter would be useable on the high noise low bands.
Most of the time on receive I use the 500 Hz with short Beverage antennas.
73 Hardy N7RT
At 11:53 AM 4/19/2007 -0400, email@example.com wrote:
>Ok I have an FT-1000mp Mark V. While it is off at
>yaesu have a problem fixed with the CAT system. Yeah
>it is me again. Nothing I tried would get the CAT to
>work. So off it goes to Yaesu....
>While I'am waiting for it to come back I wanted to
>get Some of the INRAD filters & mods coming.
>What would ya'll recommend either the Roofing Mod. or
>the 70mhz Front End Mod.
>As for the filters I mainly operate CW in a
>contesting environment I plan on the 250hz for both
>the 455khz & the 8.215mhz.
>What are the thoughts on the 125hz for the low bands.
>What are most of ya'll using.
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