Having both owned and used TS-850's for a long time in the past. A
stock kenwood 250 Hz 455 IF will work just fine. Used them this way at
W5KFT for many many years. Never operated any 250 Hz filter that didn't
work fine that came from Icom (751, 761, 765) Kenwood 930, 850. Yaesu
FT-1000D. No doubt inrad's might be better.
However, if you are using sound card RTTY then wider might actually be
better. But I continue to use hardware modems along with sound cards in
combo. I have used the cocoaModem and 2.0 Khz filters, but Chen writes
much better software than what most windows folks are using.
Jay WS7I
On 7/22/2012 4:52 PM, Joe Subich, W4TV wrote:
> John,
>
>> I can only buy one filter, wanting the most filtering for blood and
>> guts 160 cw tests, but open enough to allow for fsk operation.
> When you say FSK operation that fairly clearly puts a "400 Hz" lower
> limit on the bandwidth and leaves you with two choices the 8830 KHz
> (1st IF) filter or the 455 KHz (2nd IF) filter.
>
> The 1st IF filter will provide a bit better RX IMD performance by
> getting the "narrow" filter earlier in the IF chain but the 2nd IF
> filter will provide slightly sharper skirts because of its lower
> frequency. You can see the filter curves at www.inrad.net.
>
> The 1st IF Filter is slightly less expansive than the 2nd. If it
> were me, I'd flip a coin and get one now and pick up the second one
> when conditions/finances allow. Ultimately you will want the pair.
>
> 73,
>
> ... Joe, W4TV
>
>
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