[GreenKeys] Terminal unit (HAL ST-5000) adjustment
Ethan Blanton
elb at kb8ojh.net
Sun Jan 7 21:25:52 EST 2018
Ralph Mowery wrote:
> >From what you are saying you are using low tones, but have a filter set at
> 2260. That does not sound right at all.
The 2260 was a typo (or perhaps a thinko?); it should have been 1360,
which is the center point for low tones (1275/1445). Fldigi specifies
its frequency for FSK by the midpoint, not mark (which I think was
more common for vintage equipment). My alignment was performed for
the correct low-tone frequency pair as specified in the ST-5000
manual.
> I am not familiar with the drake 2b and filtering arrangement ,but if it is
> adjustable for center frequency, it should be much lower than 2000 if using
> low tones. If the ellipses are not at right angles to each other, then the
> filters are not exactly tuned, but if not off too far you should be able to
> copy ok.
The Drake filter was centered around the low tones, near 1360. (I
don't know exactly where, and the 2-B filters are not exactly
symmetric.)
It was my experience that I could indeed copy OK with the ellipses not
at right angles, but only under near-ideal conditions.
Thanks for your input!
Ethan
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