Re: Extra capacitors in your BITX...?
Hans Summers <Hans.Summers@...>
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that if you want to see an English translation, you could try the Altavista
"babel fish" see http://babelfish.altavista.com/babelfish/tr.
You can type in the web page, and view the translated web page. It's rather
neat. The translation is obviously not perfect but it's quite easy to follow the
ideas. If you look at the home page http://www.cqham.ru/index.phtml you'll
find all kind of gems. Numerous transceiver projects etc. Also many downloaded
QST articles, and more. There is an English flag on the home page which provides
a translation, but it does not work as well as the Altavista
73 Hans G0UPL
From what I could make out of mechanical translations, the concept
among RU friends was popularised with Ural 84 design. Desna was the more
updated version probably it means dew.
the RU page for Desna design is here:
The main board ckt I am posting under files section for thers to have a
look at another way of implimenting Bi-directional concept.
did a search (using Google) for :Ural 84" and for "Desna" and did find some
textual mention of these units, but I did not find any web sites that showed
equipment or schematics. Do you have a URL that we might use to see
schematics for this equipment?
Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:
of PSK mini I also suggest looking at RU designs Ural 84 and Desna.
Similar concepts are used there while using bipolar
I am sure the coupling caps for filters can be
removed. Had I been and audiophile I would like not to
have even one of them in signal
As I sit here looking at the BITX20
schematic it 0ccured to me that
some of the capacitors may not be
1) There is a 0.1 mf on the base of Q1,
that connects to a 0.1 on
the collector of Q13. These then
connect via a 10 pf to the front-end
bandpass filter. Would it
not be acceptable to use only one 0.1 mf
between the collector of Q13
and the Base of Q1, and connect the base
of Q1 to the bandpass filter
via the 10 pf cap?
2) There is a 0.1 mf on the
collector of Q2 that connects to the
crystal filter, and another 0.1
that connects the base of Q12 to the
same point on the crystal
filter. Would it be sufficient to use just
the 0.1 mf from the
collector of Q2 to the crystal filter, and then
connect the base of
Q12 directly to the same point on that filter?
Since crystals do not
pass DC, the same amount of DC isolation would
3) There is a 0.1 mf between the end of
the crystal filter and the
base of Q3, and another 0.1 mf between
that same point on the crystal
filter and the collector of Q11.
It seems that it would suffice to
have the 0.1 mf between the
collector of Q11 and the base of Q3, with
the crystal filter simply
connected to the base of Q3. Again, the
crystal does not
conduct DC, so there would still be the same level of
OK, for all you purists out there, I know that it
symetrical with the "pairs of 0.1 mf capacitors", but are
What spawned this evaluation is my
comparison of RV3GM's PSK-20
schematic with the BITX20 design by
Farhan. I was wondering if Oleg's
method of using one
transister in bi-directional mode could also be
applied to the BITX20
where we are using pairs of transisters to
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