Re: [TenTec] Narrow Filters on Omni VI

[Jim <jlboockh@earthlink.net>]

Using a narrow filter in the 9 mhz IF eliminates the RTTY signal from 
the passband. A wide filter >2100 hz makes it audible.

You can use a narrow filter in the 6.4 mhz IF and make the RTTY signal 
audible by turning the PBT knob to about 3 o'clock. Usually I just use a 
wide filter.

I have a TT Model 216 digital filter in my Omni V.9 in Greece, and it 
works great. Someday I will get one for my Omni VI+ in the USA. If you 
want to use a narrow filter on RTTY, the 216 is the way to go.

I wanted to use FSK with my Omni's so I can set the sound card output 
level for PSK31 and not have to adjust it for AFSK.

				Jim  N4AL

Mark Erbaugh wrote:
> I'm trying to set up my Omni VI (opt 3) for the upcoming RTTY contest.  I
> have 250 and 500 Hz filters in both IFs. The 9 MHz filters are centered for
> CW.
>
> What the difference in using a narrow filter in the 9 MHz IF vs the 6 MHz
> IF. I do realize that I can center the passband of the 6 MHz with the PBT
> adjustment.  Would performance improve if I cascaded filters using a 250 in
> each IF. Since I'm can use AFSK that should be possible, I just won't be
> using "standard" RTTY tones.
>
> I understand that if I want to use FSK, I'd have to use the 6 MHz filter and
> offset it with PBT. The passband of the 9 MHz filter is not going to pass
> standard RTTY tones.
>
> Also, what are the other pros and cons of using FSK vs AFSK? I realize that
> with AFSK, I have to worry about the computer audio level and that it
> probably takes a little more horsepower from the computer / soundcard to
> generage the AFSK tone, but is there anything else to consider?
>
> 73,
> Mark
>
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