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At Dayton I got an INRAD 500 Hz CW filter to tighten up the passband
for PSK31 use. Here I am using the Menu #26 DIG=PSK31-U mode, so the
filter is enabled with #38 FILTER=CW.

What I see happen is that when the filter is enabled with NAR, the
frequency jumps 30 Hz higher. I have checked and there is no on/off
frequency shift in CW or sideband (with #38 set to SSB).

Since these filters are passive devices, and since no offset is seen
in SSB or CW, this seems to me to be a bug. With PSK31 bandwidths
being so narrow, it is a pretty serious flaw. Has anyone else seen
this problem? Or, by chance, is there a chance that this apparent bug
is in fact an "unadvertised feature" (following the proud tradition
of Windoze software)?

73 de Tom, W3IWI (private replies to w3iwi @ amsat.org)

Hello Tom,

At Dayton I got an INRAD 500 Hz CW filter to tighten up the passband
for PSK31 use. Here I am using the Menu #26 DIG=PSK31-U mode, so the
filter is enabled with #38 FILTER=CW.

What I see happen is that when the filter is enabled with NAR, the
frequency jumps 30 Hz higher. I have checked and there is no on/off
frequency shift in CW or sideband (with #38 set to SSB).

I ran into this problem also at the weekend - when I first used
PSK31 (coolest digital mode ever.. ;-)

Since these filters are passive devices, and since no offset is seen
in SSB or CW, this seems to me to be a bug. With PSK31 bandwidths
being so narrow, it is a pretty serious flaw. Has anyone else seen
this problem? Or, by chance, is there a chance that this apparent bug
is in fact an "unadvertised feature" (following the proud tradition
of Windoze software)?

You're right.. The shift comes from the software. But if you set
"26 DIG MODE" to "USER U", the mysterious shift disappears. The
only thing with this is, that the passband shifts from
1000Hz to 1500Hz.. But I believe you can program that also in
this "user mode".

Hope this helps.

73 de Michael, DL1BFF

I have this same problem with one of their filters that I purchased at Dayton last year for my Ten-Tec Omni 6+. One of the reasons I did not purchase one of their 817 SSB filters at Dayton.

Duffy - WB8NUT

Michael Dirska, DL1BFF noted

You're right.. The shift comes from the software. But if you set
"26 DIG MODE" to "USER U", the mysterious shift disappears. The
only thing with this is, that the passband shifts from
1000Hz to 1500Hz.. But I believe you can program that also in
this "user mode".

Michael was 100% right -- using USER-U instead of PSK31-U solves the
problem. The filter does end up with a passband from 1000 to 1500 Hz,
which works very well with HamScan PSK31 software. Thanks for the
hint.

I still assert that the frequency shift that I originally reported is
a nasty bug in the 817's firmware. But it's good that there was such
a simple fix.

73 de Tom, W3IWI

--- In FT817@y..., Michael Dirska <md@m...> wrote:

Hello Tom,

At Dayton I got an INRAD 500 Hz CW filter to tighten up the

passband

for PSK31 use. Here I am using the Menu #26 DIG=PSK31-U mode, so

the

filter is enabled with #38 FILTER=CW.

What I see happen is that when the filter is enabled with NAR, the
frequency jumps 30 Hz higher. I have checked and there is no

on/off

frequency shift in CW or sideband (with #38 set to SSB).

I ran into this problem also at the weekend - when I first used
PSK31 (coolest digital mode ever.. ;-)

Since these filters are passive devices, and since no offset is

seen

in SSB or CW, this seems to me to be a bug. With PSK31 bandwidths
being so narrow, it is a pretty serious flaw. Has anyone else seen
this problem? Or, by chance, is there a chance that this apparent

bug

is in fact an "unadvertised feature" (following the proud

tradition

of Windoze software)?

You're right.. The shift comes from the software. But if you set
"26 DIG MODE" to "USER U", the mysterious shift disappears. The
only thing with this is, that the passband shifts from
1000Hz to 1500Hz.. But I believe you can program that also in
this "user mode".

Hope this helps.

73 de Michael, DL1BFF