?
Hello
Ron
?
The
crystal is 32KHz not MHz! Well, 32.768KHz to be precise, which is an ordinary
watch crystal. The 1-chip stabiliser is a little sensitive to adjustment. The
resistor ratios in the VFO gating (mine show 56K and 10K) and the differentiator
time constant (22pF with 10K) need to be chosen (i.e. adjusted) quite carefully
to get it to work. Nevertheless, it does work. Arv K7HKL and I have both
succesfully built the 1-chip stabiliser. The 2-chip stabiliser?is neat
because the spare half of the 74HC74 behaves as VFO. The 2-chip design is easy
to get working, it is not sensitive to ultra-precise choice of component values.
?
Thanks
for the panoramic adapter link, I will forward it to my correspondent who is
interested in building such a device.
?
73 and
good luck
?
Hans
G0UPL
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Thanks for advice dear Hans,
Sure the instability of the vfo will increase the the frequency
increase.
I was amazed by the one-chip huff&puff circuit on your site with the
32MHz xtal.
Effective and very simple! I knew that zenerdiodes could be used as
varicaps, but led's that's new for me.
Try this one if you are interested in homebrew Panoramareceivers:
Have fun,
Ron
Hans Summers
wrote:
Hi
Ron
Thanks for the nice complements about my website :-)? I had
a look around
your website this morning, you have some very interesting
projects there. I
sent an email to a fellow who I know is interested in
panoramic adapters and
has been corresponding with me about my spectrum
analyser (
)
If
you are going to build one of the earlier designs, I have most of
the
Huff Puff articles in my reference library for download, see
. In performance
terms, I think my 2-chip simplification should perform
as well as the
original Huff Puff designs. For the ultimate performance,
G7IXH's "fast"
stabiliser is slightly more complex but performs
best.
I do know that people have used BITX20's for PSK31 very
successfully. But
don't forget that your VFO for 17m is twice the BITX20
VFO's frequency,
therefore it is bound to be less stable (all other
things being equal).
73 Hans G0UPL
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