[GreenKeys] Terminal unit (HAL ST-5000) adjustment

[Jeff Stai]

A few things...

- Contact HAL support. They should be able to send you a PDF of the service
manual, schematics, and/or alignment procedure. The last time I contacted
them they were extremely helpful and even excited to help a (fellow!) ham
with an older unit. (I have ST-8000s, the tuneup procedure is pretty
involved...) Heck, describe the issue and they may have ideas for you.

- Take a moment to characterize the actual width of the Drake 2B 500Hz
bandpass. If it is significantly narrower than 500, then the decoder may
not be getting the full spectral content it needs to properly decode. Or
that asymmetry is biting you somehow.

- Otherwise, I'd set up an RYRYRY...  pattern at the input and start signal
tracing. Just follow MARK and SPACE through each stage until something
shows itself.

Hope this helps a little - jeff wk6i


On Sun, Jan 7, 2018 at 6:25 PM, Ethan Blanton <elb at kb8ojh.net> wrote:

> 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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-- 
Jeff Stai ~ wk6i.jeff at gmail.com
Twisted Oak Winery ~ http://www.twistedoak.com/
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