From: "Garry Shapiro" <garry@ni6t.com>
To: "Ford Peterson" <ford@cmgate.com>
...snip...
> Older "multimode" controllers utilized the classic bandpass
> filter/limiter/discriminator/lowpass filter approach. This can and should
> work well, but, to minimize parts count, the units were really
> two-mode---VHF packet, and everything else. The "everything else" mode
> included RTTY, AMTOR, HF Packet, WEFAX, etc; the filter and discriminator
> bandwidths were set for the widest modes, and were suboptimal for RTTY. I
> know this was the case for the PK232, and I presume it to be true for
other
> controllers of that era.Performance can be stunningly improved.
>
Garry, to compare the KAM Plus to a PK232 is like comparing a Lexus to a
Hundai. The Kam uses a pair of MF10 filters to process the signals. I can,
in software, control the bandwidth and center frequency of each Mark and
Space. The PK232 uses a single arrangement that captures a passband.
Having run both units side-by-side I can promise you that the KAM, properly
configured, with outperform the PK anyday.
...SNIP...
> 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
> with logic levels, and most certainly do not eliminate your audio stages.
> What it does free you from is the necessity to worry about microphone gain
> and the status of your compressor.
>
It seems like your comment is really radio driven. The KAM provides logic 0
and 1 to the radio, which keys my radio's VFO (or LO). No mic gain controls
to mess up. No compressors/emphasis/etc. to distort. Garry, there is
nothing hooked to the mic circuit whatsoever. The audio stages are not an
issue. I'm not sure I understand your comment.
End-of-thread
Ford-N0FP
ford@cmgate.com
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