Topics

Extra capacitors in your BITX...?

Arvid Evans <arvevans@...>
 

Hello

As I sit here looking at the BITX20 schematic it 0ccured to me that
some of the capacitors may not be necessary:

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
be maintained.

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
DC isolation.

OK, for all you purists out there, I know that it looks more
symetrical with the "pairs of 0.1 mf capacitors", but are they really
necessary?

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
obtain bi-directionality.

Arv-K7HKL
_._

Rahul Srivastava
 

Hi!
 
On mention of PSK mini I also suggest looking at RU designs Ural 84 and Desna. Similar concepts are used there while using bipolar transistors.
 
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 path.
 
73
 
Rahul VU3WJM
 
 


Arvid Evans wrote:
Hello

As I sit here looking at the BITX20 schematic it 0ccured to me that
some of the capacitors may not be necessary:

  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
be maintained.

  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
DC isolation.

OK, for all you purists out there, I know that it looks more
symetrical with the "pairs of 0.1 mf capacitors", but are they really
necessary?

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
obtain bi-directionality. 

Arv-K7HKL
_._



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Arv Evans <arvevans@...>
 

Rahul-VU3WJM

I 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?

Thanks,
Arv-K7HKL
_._

On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:
Hi!
 
On mention of PSK mini I also suggest looking at RU designs Ural 84 and Desna. Similar concepts are used there while using bipolar transistors.
 
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 path.
 
73
 
Rahul VU3WJM
 
 

Arvid Evans wrote:
Hello

As I sit here looking at the BITX20 schematic it 0ccured to me that
some of the capacitors may not be necessary:

  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
be maintained.

  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
DC isolation.

OK, for all you purists out there, I know that it looks more
symetrical with the "pairs of 0.1 mf capacitors", but are they really
necessary?

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
obtain bi-directionality. 

Arv-K7HKL
_._



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  • Rahul Srivastava
     

    Dear Arv,
     
    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. 
     
    73
     
    Rahul VU3WJM
     
     
     


    Arv Evans wrote:
    Rahul-VU3WJM

    I 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?

    Thanks,
    Arv-K7HKL
    _._

    On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:
    Hi!
     
    On mention of PSK mini I also suggest looking at RU designs Ural 84 and Desna. Similar concepts are used there while using bipolar transistors.
     
    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 path.
     
    73
     
    Rahul VU3WJM
     
     

    Arvid Evans wrote:
    Hello

    As I sit here looking at the BITX20 schematic it 0ccured to me that
    some of the capacitors may not be necessary:

      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
    be maintained.

      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
    DC isolation.

    OK, for all you purists out there, I know that it looks more
    symetrical with the "pairs of 0.1 mf capacitors", but are they really
    necessary?

    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
    obtain bi-directionality. 

    Arv-K7HKL
    _._



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    Hans Summers <Hans.Summers@...>
     

     
    BITX'ers
     
    Note 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 page.
     
    73 Hans G0UPL
    http://www.HansSummers.com

    -----Original Message-----
    From: Rahul Srivastava [mailto:vu3wjm@...]
    Sent: 01 October 2004 06:57
    To: BITX20@...
    Subject: Re: [BITX20] Extra capacitors in your BITX...?

    Dear Arv,
     
    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. 
     
    73
     
    Rahul VU3WJM
     
     
     


    Arv Evans wrote:
    Rahul-VU3WJM

    I 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?

    Thanks,
    Arv-K7HKL
    _._

    On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:
    Hi!
     
    On mention of PSK mini I also suggest looking at RU designs Ural 84 and Desna. Similar concepts are used there while using bipolar transistors.
     
    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 path.
     
    73
     
    Rahul VU3WJM
     
     

    Arvid Evans wrote:
    Hello

    As I sit here looking at the BITX20 schematic it 0ccured to me that
    some of the capacitors may not be necessary:

      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
    be maintained.

      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
    DC isolation.

    OK, for all you purists out there, I know that it looks more
    symetrical with the "pairs of 0.1 mf capacitors", but are they really
    necessary?

    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
    obtain bi-directionality. 

    Arv-K7HKL
    _._



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    Arvid Evans <arvevans@...>
     

    Rahul & Hans

    Thanks for the info on the RU designed Desna Xcvr. It is interesting
    that they used a valve-type linear instead of solid state.

    In the Desna design, Vt2 and VT3 layouts do show one way of obtaining
    proper bias when using BJTs in a bi-directional layout.

    After looking at the Desna and the PSK-20 by RV3GM, I opened Eagle CAD
    and put together a quick conceptual drawing of a minimalist DSB Xcvr
    layout that uses this switched bidirectional amplifier idea. The
    result has been uploaded to <BITX20/FILES/K7HKL/DSB-Mite "Conceptual
    Drawing".gif> if anyone wants to look and comment.
    NOTE: THIS IS A CONCEPTUAL DRAWING ONLY...NOT TESTED...DO NOT BUILD
    FROM THIS DRAWING.

    73
    Arv-K7HKL

    --- In BITX20@..., Hans Summers <Hans.Summers@t...> wrote:

    BITX'ers

    Note that if you want to see an English translation, you could try the
    Altavista "babel fish" see http://babelfish.altavista.com/babelfish/tr
    <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
    <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 page.

    73 Hans G0UPL
    http://www.HansSummers.com

    -----Original Message-----
    From: Rahul Srivastava [mailto:vu3wjm@y...]
    Sent: 01 October 2004 06:57
    To: BITX20@...
    Subject: Re: [BITX20] Extra capacitors in your BITX...?


    Dear Arv,

    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:

    http://www.cqham.ru/desna.htm <http://www.cqham.ru/desna.htm>

    The main board ckt I am posting under files section for thers to
    have a look
    at another way of implimenting Bi-directional concept.

    73

    Rahul VU3WJM





    Arv Evans <arvevans@e...> wrote:

    Rahul-VU3WJM

    I 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?

    Thanks,
    Arv-K7HKL
    _._

    On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:

    Hi!

    On mention of PSK mini I also suggest looking at RU designs Ural 84 and
    Desna. Similar concepts are used there while using bipolar transistors.

    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 path.

    73

    Rahul VU3WJM



    Arvid Evans <arvevans@e...> wrote:

    Hello

    As I sit here looking at the BITX20 schematic it 0ccured to me that
    some of the capacitors may not be necessary:

    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
    be maintained.

    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
    DC isolation.

    OK, for all you purists out there, I know that it looks more
    symetrical with the "pairs of 0.1 mf capacitors", but are they really
    necessary?

    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
    obtain bi-directionality.

    Arv-K7HKL
    _._



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    Rahul Srivastava
     

    Dear Hans and Arv
     
    Hi!
     
    It is indeed pleasure to see some interest in ones post. I find this as a case of history repeating itself. Similar on the line of two different concept that evolved during development of a space suit one a 7 layered design and other in RU teritories almirah door type ones.
     
    Hams I see you did some serious work on the hammer/ screwdriver page ( This is what i comprehend from the icon). At times it appeared funny to see something translated like the administration is done by change it pressure. Ultimately it boiled down to to freq control is manged by change in voltage, a description of PLL sections.
     
    A brief lineup of RU designs would be in order for RU TRXs, UW3DI, Ural84, Desna, Don-M and many others with some peculiar characters.
     
    Now on the topic there are another few page of these region that also need some looking into for hombrew projects:
     
     
    and yet another
     
     
    Hope all enjoy.
     
    73
     
    Rahul VU3WJM
     

    Hans Summers wrote:
     
    BITX'ers
     
    Note 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 page.
     
    73 Hans G0UPL
    http://www.HansSummers.com
    -----Original Message-----
    From: Rahul Srivastava [mailto:vu3wjm@...]
    Sent: 01 October 2004 06:57
    To: BITX20@...
    Subject: Re: [BITX20] Extra capacitors in your BITX...?

    Dear Arv,
     
    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. 
     
    73
     
    Rahul VU3WJM
     
     
     


    Arv Evans wrote:
    Rahul-VU3WJM

    I 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?

    Thanks,
    Arv-K7HKL
    _._

    On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote:
    Hi!
     
    On mention of PSK mini I also suggest looking at RU designs Ural 84 and Desna. Similar concepts are used there while using bipolar transistors.
     
    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 path.
     
    73
     
    Rahul VU3WJM
     
     

    Arvid Evans wrote:
    Hello

    As I sit here looking at the BITX20 schematic it 0ccured to me that
    some of the capacitors may not be necessary:

      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
    be maintained.

      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
    DC isolation.

    OK, for all you purists out there, I know that it looks more
    symetrical with the "pairs of 0.1 mf capacitors", but are they really
    necessary?

    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
    obtain bi-directionality. 

    Arv-K7HKL
    _._



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    Arvid Evans <arvevans@...>
     

    Dear Rahul

    Thank you for the information on RU area transceivers. It will take a
    while to translate and understand all this, but it is very interesting
    reading.

    Thanks,
    Arv K7HKL
    _._

    --- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:
    Dear Hans and Arv

    Hi!

    It is indeed pleasure to see some interest in ones post. I find this
    as a case of history repeating itself. Similar on the line of two
    different concept that evolved during development of a space suit one
    a 7 layered design and other in RU teritories almirah door type ones.

    Hams I see you did some serious work on the hammer/ screwdriver page
    ( This is what i comprehend from the icon). At times it appeared funny
    to see something translated like the administration is done by change
    it pressure. Ultimately it boiled down to to freq control is manged by
    change in voltage, a description of PLL sections.

    A brief lineup of RU designs would be in order for RU TRXs, UW3DI,
    Ural84, Desna, Don-M and many others with some peculiar characters.

    Now on the topic there are another few page of these region that
    also need some looking into for hombrew projects:

    http://ra3ggi.qrz.ru/

    and yet another

    http://www.qsl.net/sp3abg/index.html

    Hope all enjoy.

    73

    Rahul VU3WJM


    Hans Summers <Hans.Summers@t...> wrote:

    BITX'ers

    Note 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 page.

    73 Hans G0UPL
    http://www.HansSummers.com

    -----Original Message-----
    From: Rahul Srivastava [mailto:vu3wjm@y...]
    Sent: 01 October 2004 06:57
    To: BITX20@...
    Subject: Re: [BITX20] Extra capacitors in your BITX...?


    Dear Arv,

    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:

    http://www.cqham.ru/desna.htm

    The main board ckt I am posting under files section for thers to
    have a look at another way of implimenting Bi-directional concept.

    73

    Rahul VU3WJM





    Arv Evans <arvevans@e...> wrote:
    Rahul-VU3WJM

    I 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?

    Thanks,
    Arv-K7HKL
    _._

    On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote: Hi!

    On mention of PSK mini I also suggest looking at RU designs Ural 84
    and Desna. Similar concepts are used there while using bipolar
    transistors.

    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 path.

    73

    Rahul VU3WJM



    Arvid Evans <arvevans@e...> wrote: Hello

    As I sit here looking at the BITX20 schematic it 0ccured to me that
    some of the capacitors may not be necessary:

    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
    be maintained.

    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
    DC isolation.

    OK, for all you purists out there, I know that it looks more
    symetrical with the "pairs of 0.1 mf capacitors", but are they really
    necessary?

    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
    obtain bi-directionality.

    Arv-K7HKL
    _._



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    Rahul Srivastava
     

    Hi!
     
    Arv,
     
    This area is indeed a new ball game all to gether.But it indeed represents a some new concepts. I hope we can have a ckt consistant with the general available components. I would be only too glad to make a board based on that for my friends.
     
    TNX once again for adding fuel to the hombrew fire. 
     
    73
     
    Rahul VU3WJM
     
     
     
     


    Arvid Evans wrote:
    Dear Rahul

    Thank you for the information on RU area transceivers.  It will take a
    while to translate and understand all this, but it is very interesting
    reading.

    Thanks,
    Arv K7HKL
    _._

    --- In BITX20@..., Rahul Srivastava wrote:
    > Dear Hans and Arv

    > Hi!

    > It is indeed pleasure to see some interest in ones post. I find this
    as a case of history repeating itself. Similar on the line of two
    different concept that evolved during development of a space suit one
    a 7 layered design and other in RU teritories almirah door type ones.

    > Hams I see you did some serious work on the hammer/ screwdriver page
    ( This is what i comprehend from the icon). At times it appeared funny
    to see something translated like the administration is done by change
    it pressure. Ultimately it boiled down to to freq control is manged by
    change in voltage, a description of PLL sections.

    > A brief lineup of RU designs would be in order for RU TRXs, UW3DI,
    Ural84, Desna, Don-M and many others with some peculiar characters.

    > Now on the topic there are another few page of these region that
    also need some looking into for hombrew projects:

    > http://ra3ggi.qrz.ru/

    > and yet another

    > http://www.qsl.net/sp3abg/index.html

    > Hope all enjoy.

    > 73

    > Rahul VU3WJM

    >
    > Hans Summers wrote:

    > BITX'ers

    > Note 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 page.

    > 73 Hans G0UPL
    > http://www.HansSummers.com
    >
    > -----Original Message-----
    > From: Rahul Srivastava [mailto:vu3wjm@y...]
    > Sent: 01 October 2004 06:57
    > To: BITX20@...
    > Subject: Re: [BITX20] Extra capacitors in your BITX...?
    >
    >
    > Dear Arv,

    > 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:

    > http://www.cqham.ru/desna.htm

    > The main board ckt I am posting under files section for thers to
    have a look at another way of implimenting Bi-directional concept.

    > 73

    > Rahul VU3WJM



    >
    >
    > Arv Evans wrote:
    > Rahul-VU3WJM
    >
    > I 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?
    >
    > Thanks,
    > Arv-K7HKL
    > _._
    >
    > On Wed, 2004-09-29 at 22:17, Rahul Srivastava wrote: Hi!

    > On mention of PSK mini I also suggest looking at RU designs Ural 84
    and Desna. Similar concepts are used there while using bipolar
    transistors.

    > 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 path.

    > 73

    > Rahul VU3WJM


    >
    > Arvid Evans wrote: Hello
    >
    > As I sit here looking at the BITX20 schematic it 0ccured to me that
    > some of the capacitors may not be necessary:
    >
    >   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
    > be maintained.
    >
    >   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
    > DC isolation.
    >
    > OK, for all you purists out there, I know that it looks more
    > symetrical with the "pairs of 0.1 mf capacitors", but are they really
    > necessary?
    >
    > 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
    > obtain bi-directionality. 
    >
    > Arv-K7HKL
    > _._
    >
    >
    >
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    >
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    >
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