I was a casual reader of "Communications Quarterly" A local Tower Records,
of all places, carried it and when I was in the area I would pick up a copy.
On my last trip I could not find the magazine. Too bad, it was a good
publication.
I think the MODS you refer to are at http://www.qsl.net/k0bx
I am an occasional RTTY operator, so doing the MODS will be far down the
"to-do" list.
On the FSK issue, I thought that all "FSK" ready radios generated true FSK.
Ya' learn something every day.
I don't know if the other TT radios are set up for FSK.
Jim
> I wrote an article for the now-defunct "Communications Quarterly" in 1993,
> and then did some additional work. The mods scale down the bandwidth of
the
> front end bandpass filter by almost a factor of 2 (user-selectable), and
the
> post-detection LPF by about 5, without affecting VHF packet performance.
> Aftermarket DSP boxes can now substitute for the front-end scaling (only).
I
> also double the Q of the discriminator resonators, which changes the
> transfer characteristic from the classic "S-curve", which is best for the
> 300 bps modes, to a double-humped response more suited to the spectrum of
an
> FSK signal.
>
> The mods involve replacing a handful of 1% resistors and going through a
> tuning procedure on the front-end BPF that requires a dual-channel scope
or
> other phase-comparison device.
>
> Over the years, I have sent copies of the article and subsequent additions
> to many requestors, at least one of whom may actually have done the mods.
> :-) I have several requests in the hopper and I would be happy to send
> copies to anyone willing to send me an SAE and $2 to cover copying a dozen
> pages and mailing a 3 ounce letter.
> >
> > > You say your KAM "actually keys true FSK," but that is not correct.
The
> > KAM,
> > > and all other "FSK" sources, provide logic-level outputs that do not
> > > directly manipulate the frequency generator in your radio, but which
> > select
> > > dividers in the radio that provide tones to modulate your SSB
> > transmitter
> > > downstream from your microphone preamps. IOW, you are merely
generating
> > AFSK
> >
> > I don't know about the KAM, but the PK-232 provides a discrete output
for
> > FSK. When used with a TT OMNI-VI+, this voltage is applied to
> > the VFO and a
> > varactor diode shifts the VFO frequency, providing true FSK.
> >
> > Jim
> >
> That is indeed true FSK, and that is the first modern radio I have heard
of
> that does that. So, if Ford, N0FP has an Omni VI, his claim of bypassing
all
> audio circuitry was correct. Thank you for that input and correction--I
had
> hoped that my statement would bring forth that information. I wonder if
> other Tentec radios do the same.
>
> Garry, NI6T
>
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