Date   
Re: Extra capacitors in your BITX...?

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
_._



_____

Do you Yahoo!?
<http://vote.yahoo.com/> vote.yahoo.com - Register online to vote
today!

Yahoo! Groups Sponsor

ADVERTISEMENT

<http://us.ard.yahoo.com/SIG=1298tr70v/M=295196.4901138.6071305.3001176/D=gr
oups/S=1705063108:HM/EXP=1096604253/A=2128215/R=0/SIG=10se96mf6/*http://comp
anion.yahoo.com> click here

<http://us.adserver.yahoo.com/l?M=295196.4901138.6071305.3001176/D=groups/S=
:HM/A=2128215/rand=154729275>

_____

Yahoo! Groups Links

* To visit your group on the web, go to:
<http://groups.yahoo.com/group/BITX20/>
http://groups.yahoo.com/group/BITX20/


* To unsubscribe from this group, send an email to:
<mailto:BITX20-unsubscribe@...?subject=Unsubscribe>
BITX20-unsubscribe@...


* Your use of Yahoo! Groups is subject to the
<http://docs.yahoo.com/info/terms/> Yahoo! Terms of Service.

*




====================================
D E E P S P A C E R A D I O S Y S T E M S


ENGINEERING SERVICES:
* System Design
* Project Planning
* Project Management
* Deployment
* Operation Planning & Support

CONTACT: arvevans@e...
====================================
<http://us.f414.mail.yahoo.com/ym/Ham_DSRS@...>





_____

Do you Yahoo!?
vote.yahoo.com <http://vote.yahoo.com> - Register online to vote
today!

Yahoo! Groups Sponsor

ADVERTISEMENT

<http://us.ard.yahoo.com/SIG=129v85j3h/M=295196.4901138.6071305.3001176/D=gr
oups/S=1705063108:HM/EXP=1096696597/A=2128215/R=0/SIG=10se96mf6/*http://comp
anion.yahoo.com> click here

<http://us.adserver.yahoo.com/l?M=295196.4901138.6071305.3001176/D=groups/S=
:HM/A=2128215/rand=686284971>


_____

Yahoo! Groups Links


* To visit your group on the web, go to:
http://groups.yahoo.com/group/BITX20/
<http://groups.yahoo.com/group/BITX20/>


* To unsubscribe from this group, send an email to:
BITX20-unsubscribe@...
<mailto:BITX20-unsubscribe@...?subject=Unsubscribe>


* Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
<http://docs.yahoo.com/info/terms/> .

Re: Extra capacitors in your BITX...?

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
_._



Do you Yahoo!?

vote.yahoo.com - Register online to vote today!

Yahoo! Groups Sponsor
ADVERTISEMENT
click here


Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   


  • Do you Yahoo!?
    vote.yahoo.com - Register online to vote today!

    New file uploaded to BITX20

    BITX20@...
     

    Hello,

    This email message is a notification to let you know that
    a file has been uploaded to the Files area of the BITX20
    group.

    File : /desna.gif
    Uploaded by : vu3wjm <vu3wjm@...>
    Description : Another way to impliment Bi-directional concept.

    You can access this file at the URL:
    http://groups.yahoo.com/group/BITX20/files/desna.gif

    To learn more about file sharing for your group, please visit:
    http://help.yahoo.com/help/us/groups/files

    Regards,

    vu3wjm <vu3wjm@...>

    Re: Extra capacitors in your BITX...?

    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
    _._



    Do you Yahoo!?

    vote.yahoo.com - Register online to vote today!

    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   


  • Do you Yahoo!?
    vote.yahoo.com - Register online to vote today!

    Re: Extra capacitors in your BITX...?

    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
    _._



    Do you Yahoo!?

    vote.yahoo.com - Register online to vote today!

    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   
  • Re: Extra capacitors in your BITX...?

    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
    _._



    Do you Yahoo!?
    vote.yahoo.com - Register online to vote today!

    Re: Progress with BITX

    Arv Evans <arvevans@...>
     

    John-G0UCP

    Congratulations on the birth of your new BITX20 transceiver!


    Arv-K7HKL
    _._
    On Wed, 2004-09-29 at 13:02, market10gardener wrote:
    Hi
    I'm pleased to say that my BITX20 is now complete and it performs
    exactly as described. With my 132' doublet it has received excellent
    reports incuding 59 from PJ4 in one direction and UN7 in the other.
    Like Chris I made a few contacts with the penultimate (2N2218) stage
    on its own and these included an island off the coast of ES which was
    satisfying with 100Mw.
    At first the PA was a little unstable so I put in a small (abt 45pf)
    trimmer capacitor from the gate to the drain of the IRF510, lowered
    the value of the 2.2K resistor between the base and collector of the
    2N2218 by putting a 1K resistor in parallel with it and substituted a
    300pf cap for the 0.1mf between the drain of the IRF510 and the low
    pass filter. I now get 4 watts with a 12 volt power supply and 5
    watts with about 13v from a 17 Ah storage battery.
    I heard VU2PEP wkg most of North America (with 200 watts) the other
    evening but the pile up was formidable. It would be nice to meet
    another BITX on the air. Is any one interested in taking one along to
    Rochdale on the 9th October?
    72, 73
    John  G0UCP


    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   
  • 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
    _._

    Progress with BITX

    market10gardener <market10gardener@...>
     

    Hi
    I'm pleased to say that my BITX20 is now complete and it performs
    exactly as described. With my 132' doublet it has received excellent
    reports incuding 59 from PJ4 in one direction and UN7 in the other.
    Like Chris I made a few contacts with the penultimate (2N2218) stage
    on its own and these included an island off the coast of ES which was
    satisfying with 100Mw.
    At first the PA was a little unstable so I put in a small (abt 45pf)
    trimmer capacitor from the gate to the drain of the IRF510, lowered
    the value of the 2.2K resistor between the base and collector of the
    2N2218 by putting a 1K resistor in parallel with it and substituted a
    300pf cap for the 0.1mf between the drain of the IRF510 and the low
    pass filter. I now get 4 watts with a 12 volt power supply and 5
    watts with about 13v from a 17 Ah storage battery.
    I heard VU2PEP wkg most of North America (with 200 watts) the other
    evening but the pile up was formidable. It would be nice to meet
    another BITX on the air. Is any one interested in taking one along to
    Rochdale on the 9th October?
    72, 73
    John G0UCP

    Re: Progress with BITX

    Charles Darley
     

    I wish I could make the event but I have a 21st birthday of my daughter to attend ...  Would have been nice to have met up with you ...
     
    Mine has still a long way to go as I have had so many other commitments with the BRATS ...
     
    Regards Charles  G4VSZ
     
     

    -----Original Message-----
    From: market10gardener [mailto:market10gardener@...]
    Sent: 29 September 2004 20:03
    To: BITX20@...
    Subject: [BITX20] Progress with BITX


    Hi
    I'm pleased to say that my BITX20 is now complete and it performs
    exactly as described. With my 132' doublet it has received excellent
    reports incuding 59 from PJ4 in one direction and UN7 in the other.
    Like Chris I made a few contacts with the penultimate (2N2218) stage
    on its own and these included an island off the coast of ES which was
    satisfying with 100Mw.
    At first the PA was a little unstable so I put in a small (abt 45pf)
    trimmer capacitor from the gate to the drain of the IRF510, lowered
    the value of the 2.2K resistor between the base and collector of the
    2N2218 by putting a 1K resistor in parallel with it and substituted a
    300pf cap for the 0.1mf between the drain of the IRF510 and the low
    pass filter. I now get 4 watts with a 12 volt power supply and 5
    watts with about 13v from a 17 Ah storage battery.
    I heard VU2PEP wkg most of North America (with 200 watts) the other
    evening but the pile up was formidable. It would be nice to meet
    another BITX on the air. Is any one interested in taking one along to
    Rochdale on the 9th October?
    72, 73
    John  G0UCP


    Re: Ideas on using BITX20 for PSK31

    Arv Evans <arvevans@...>
     

    Jay

    Check out the FILES section and you will find several suggested circuits for the features that you mentioned.  There are two different VOX circuits there (I use the all-transistor version).  There is a circuit in FILES for adding RIT, and a bookmark in the LINKS section showing more info on this circuit.  My circuit for transistorized PTT is also in the FILES section.

    Adding the interface for PSK-31 has been discussed on this forum in the past.  All that is necessary is to take off the high-side of your Volume control with a pair of resistors to get the audio level down to where it will match the microphone input on your PC sound card.  The PSK transmit is handled by adding another resistive attenuator to match sound card output levels to the microphone input level of your BITX transceiver.  In my BITX20 I put two RCA-jacks on the rear panel and connected these to the above-mentioned attenuators.  The VOX works fine to perform Rx-Tx switching for PSK.

    Good luck,

    Arv
    _._

    On Fri, 2004-09-24 at 02:03, null1969 wrote:
    Hello all,
       I have not seen any practical designs for using BITX20 for PSK31
    mode. I am still working on completing the assembly but would like to
    learn more about what mods can be incorporated as I am building. Some
    ideas that I have thought about are:
    1. Implementing VOX so that PSK31 can be used using VOX switching.
    2. Using a transistor switch for PTT switching (similar to design
    used in Small Wonder Labs design).
    3. Building in the USB & LSB mode in the BFO (similar to the one
    illustrated by Farhan in his 2 band rig).

    Any ideas of implementions that can be uploaded to the files section?

    Regards,
    Jay


    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   
  • Ideas on using BITX20 for PSK31

    null1969
     

    Hello all,
    I have not seen any practical designs for using BITX20 for PSK31
    mode. I am still working on completing the assembly but would like to
    learn more about what mods can be incorporated as I am building. Some
    ideas that I have thought about are:
    1. Implementing VOX so that PSK31 can be used using VOX switching.
    2. Using a transistor switch for PTT switching (similar to design
    used in Small Wonder Labs design).
    3. Building in the USB & LSB mode in the BFO (similar to the one
    illustrated by Farhan in his 2 band rig).

    Any ideas of implementions that can be uploaded to the files section?

    Regards,
    Jay

    Another RIT Circuit...

    Arvid Evans <arvevans@...>
     

    Hi

    A new RIT circuit drawing has been added to
    <BITX20/Files/Modifications/K8IQY RIT Circuit.png>

    This one is a bit simpler than my earlier circuit, and in true
    BITX style this design uses an NPN transistor.

    This design came from K8IQY, but I found it on the web page
    of W1HUE.

    I added the voltage regulator sections, but these may not be
    necessary if your power source is stable.

    I also added a URL to the BITX20/Links/Modifications/ section
    that will take you to W1HUE's web site and a little different
    version of this RIT circuit.

    Arv - K7HKL
    _._

    Re: BITX20 made in brasil...!!

    Arv Evans <arvevans@...>
     

    SANDRO - PY2PE

    It seems like the BFO mixer is causing you some problems. 
    There are two slightly different schematics available for the BITX20 design.  How we troubleshoot your particular circuit is somewhat dependent on which schematic version you used to build your transceiver.  The major difference is that one has a resistive pi-network attenuator at the output of the BFO Mixer, and the other does not have this attenuator.  Maybe Farhan could tell us which one is the correct schematic?  Without knowing which diagram you used, I will assume that you have the one with the resistive attenuator after the BFO Mixer.  If you have the other, you can ignore step 5 below. 

    Listed below is a set of things to check:

    1. BFO Injection Level:  The unloaded output of Q8 should be at minimum about 6 volts AC.  If you disconnect the 1K going to the base of Q9 and using a simple half-wave RF detector you should find in excess of 5 V AC on the emitter of Q8.  Reconnect the 1K to the base of Q9 and disconnect the 0.1 between the emitter of Q9 and the mixer transformer.  You should measure in excess of 2.5 V AC as the unloaded output of Q9.  Re-connect the 0.1 between the emitter of Q9 and the mixer transformer.
    2. Audio Levels:  Disconnect the 1 MFD cap from the collector of Q10 (microphone amplifier).  With no load on the output of the microphone amplifier you can expect to see something near 6V DC on it's collector and about 2 V AC with a loud whistle into the microphone.  If you have an oscilloscope, this waveform should be close to a good sine-wave. Reconnect the 1 MFD to the collector of Q10.  Now, if you look at the output of the microphone amp with an oscilloscope, the waveform may be distorted at higher audio levels.  This is due to the loading factor caused by the base-emitter conduction of Q4, and it is normal.
    3. Mixer Transformer:  Proper phase relationships between windings of the mixer transformer is critical.  The two secondary windings must be connected as a push-pull center-tapped winding.  If they are erroneously connected in-phase, you may be able to receive, but you will not be able to transmit.  Farhan's schematic shows exactly how this connection should be accomplished from both a physical and electrical viewpoint.
    4. Mixer Diodes and Mixer Balancing Capacitors:  If the polarity of one of the BFO mixer diodes is not correct, you may be able to receive, but you will not be able to transmit SSB.  With one of the diodes reversed, you will not get a good dip in carrier output when trying to balance out the carrier.  If you disconnect the two mixer balancing capacitors (the 10 pf fixed and 22 pf variable units) you will still get a dip in un-modulated carrier output when adjusting the 100 ohm carrier balancing potentiometer.  However, it may not be as definite as can be obtained with the capacitive balancing components connected.  Remember to re-connect any capacitors or diodes that you disconnected for testing.   NOTE: The carrier balancing potentiometer must be a non-inductive (not wire-wound) type device.
    5. Mixer Attenuator/Diplexer:  Check the attenuator at the SSB side of the BFO mixer to make sure that you did not put the 22 ohm to ground and one of the 220 ohm resistors in-line with the signal path.  This attenuator should have a 220 ohm to ground, then a 22 ohm in series with the signal path, and another 220 ohm to ground.  If you accidentally swapped the 22 ohm with one of the 220 ohm resistors, this could result in the extremely low mixer output that you are experiencing.

    Beyond the tests indicated above, you may need to check the voltages on Q11 to insure that it is working properly.  Also, maybe change out Q11 on the chance that this device may have an Ft that is not high enough to provide sufficient amplification at 10 MHz.

    I hope this helps.  Please let the forum know what you found, as others may have similar problems.

    Good luck,

    Arv - K7HKL
    ---   -   ---

    On Mon, 2004-09-20 at 19:29, py1pe@... wrote:
              hello friends, 
     
         my bitx20 is with problems in the production of DSB (1st mixer), I already did of everything and he/she didn't find a way, it exists but it is extremely small, there is not apparent cause for the problem (mysteries of the electronics). 
    I should set up an entire new block. 
    the receiver works very well. 
    forced to all that tried me to help!! 
     
          SANDRO - PY2PE

    Re: BITX20 made in brasil...!!

    Chris van den Berg
     

    Hi Sandro,
    if the mixer works while receiving, it should also work with
    transmitting?
    You should have added the attenuator resistors otherwise the mixer
    do not work.
    It can be seen with an osciloscoop: without the attenuator you only
    see a lot of LF, with the attenuator (or a RFC coil to ground) you
    see HF signal 'trapped' in the LF signal.
    Indeed it is a very low level but it works.
    Best regards,
    Chris.

    --- In BITX20@..., py1pe@a... wrote:
    hello friends,

    my bitx20 is with problems in the production of DSB (1st
    mixer), I
    already did of everything and he/she didn't find a way, it exists
    but it is
    extremely small, there is not apparent cause for the problem
    (mysteries of the
    electronics).
    I should set up an entire new block.
    the receiver works very well.
    forced to all that tried me to help!!

    SANDRO - PY2PE

    Re: BITX20 made in brasil...!!

    py1pe@...
     

              hello friends, 
     
         my bitx20 is with problems in the production of DSB (1st mixer), I already did of everything and he/she didn't find a way, it exists but it is extremely small, there is not apparent cause for the problem (mysteries of the electronics). 
    I should set up an entire new block. 
    the receiver works very well. 
    forced to all that tried me to help!! 
     
          SANDRO - PY2PE

    Re: BITX20 made in brasil...!!

    Chris van den Berg
     

    Hi all,
    the information that I posted before, does contain a major mistake!
    I was forgotten that the 10 dB attenuator was still connected while
    measuring the output of Q14. So the output was not 0,3 mw but 3 mw.
    However, now I measured again and the output of Q14 is 1,2 mw and
    the output of the 2N2219 (2N2218) is now 80 mw (gain of 18dB).
    I wonder where the 3 dB went (may be this is the negative aspect of
    adding shielding ;-( )

    Increasing of the oscillator level did not result in better
    functioning mixer (it can be tested easily by adding a 0,1 uF
    capacitor over the 1K resistor between Q8 and Q9).

    By the way, adding a RFC on the 100 ohm potmeter (in the mixer) gave
    a better reduction of the AF component, however, the AF component
    will not pass the filter.

    Sorry for posting the wrong information,
    Chris.

    some additional measurement results (all loaded with 50 ohm):
    The output of Q14 is 0.3 mw, output of the 2N2219 about 150 mw
    (with much LF in the microphone stage). This means a gain of 27 dB
    (but I am sure you should not measure it all with 50 ohm load).
    Chris.

    Re: PCB Parts Layout

    Rahul Srivastava
     

    Hi!
     
    Some real efforts made there in labeling all components in original BITX layout. It appears the RIT is indeed the fine tune control.
     
    Very true the Rx front end device indeed determines the overall sensitivity and performance. I suggest giving a try to devices like 2N3866, 2N5109, 2N5179, BFW16,BFR91-96 and other devices in its class,  for RF amp as well as for post mixer one too. In past I have used 2SC2570A ( very cheap CATV component) in these places with very good results. The resistive nature of the amp would lend themself to easy adaption as well as stability. I have also noticed that 2N3904/6 has a lesser loading capacitance than the BC547s
     
    A true homebrew project in all aspect this is.
    AGC design is now what we all look forward too.
     
    73
     
    Rahul VU3WJM
     
     
     
     
     


    Arv Evans wrote:
    Manuel - EB7HPM

    Thank you for the quick reply. 
    I had noticed the notation of "RIT" on the top-left of your PC Board image and took that to indicate
    that you had a new way of doing that function.  Now I understand that this is actually the main
    VFO tuning adjustment.

    The web site you referred to is quite impressive.  It is nice to see home made (homebrew) ham
    radio equipment that has a very professional look.

    On my first BITX (a BITX20 version) I also experienced limited sensitivity, but when I replaced the
    2N2222 RF amplifier with a 2N3904 that had been selected for high gain the performance
    became very good.

    You seem to be working on some very interesting modifications of the BITX design.  I am sure
    that others would be very interested in more detail about your work.

    Several persons have commented about interest in building a BITX-144 for 2 Meters.  It seems like a worthwhile effort, and your use of heterodyne oscillators to generate the required higher
    frequencies would seem like the way to do it.  I am sure that others in this forum would be
    interested in seeing your designs.

    73's

    Arv - K7HKL
    On Mon, 2004-09-20 at 01:21, eb7hpm wrote:
    I'm sorry, but muy rig doesn't have RIT, although I hope soon to
    have it. However you can try some configurations. I remember one
    with suming AO. You can take it from here:
    http://www001.upp.so-
    net.ne.jp/jg1ead/allbander/e_ab.html

    Sorry also for my bad english :-(

    I have mounted a BITX15 in order to use it in 15m because I
    am "licensed C" in Spain and it work very well. I use FI of 10MHz
    and one external oscillator VXO to 31MHz. I have not mounted yet the
    power amplifier.

    However, the reception is a little weak and I added an cascode
    amplifier with two transistors and a coil in the FI. How it change!!
    Now I have the problem of excessive gain in some cases and I am
    working in an AGC.

    For the oscillator I am triying a VCO of 10 to 40MHz controlled by
    PLL 145170 and when it work I will control everything with a
    PIC16F84 with LCD and codec. Here some info:

    http://lpistor.chez.tiscali.fr/syntheblucw.htm

    I have put the diagram only for others have it like reference.
    I want to prepare a PCB more ambitious, with multiband change, CW,
    AGC, PLL and AM/ FM.

    As I have each part working I will put the schematic.
    I am not much spare time. :-(

    The BITX can work to 144MHz?? I hope so.

    Greetings
    Manuel EB7HPM/EC7ALV.


    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   


  • Do you Yahoo!?
    New and Improved Yahoo! Mail - Send 10MB messages!

    Re: PCB Parts Layout

    Arv Evans <arvevans@...>
     

    Manuel - EB7HPM

    Thank you for the quick reply. 
    I had noticed the notation of "RIT" on the top-left of your PC Board image and took that to indicate
    that you had a new way of doing that function.  Now I understand that this is actually the main
    VFO tuning adjustment.

    The web site you referred to is quite impressive.  It is nice to see home made (homebrew) ham
    radio equipment that has a very professional look.

    On my first BITX (a BITX20 version) I also experienced limited sensitivity, but when I replaced the
    2N2222 RF amplifier with a 2N3904 that had been selected for high gain the performance
    became very good.

    You seem to be working on some very interesting modifications of the BITX design.  I am sure
    that others would be very interested in more detail about your work.

    Several persons have commented about interest in building a BITX-144 for 2 Meters.  It seems like a worthwhile effort, and your use of heterodyne oscillators to generate the required higher
    frequencies would seem like the way to do it.  I am sure that others in this forum would be
    interested in seeing your designs.

    73's

    Arv - K7HKL
    On Mon, 2004-09-20 at 01:21, eb7hpm wrote:
    I'm sorry, but muy rig doesn't have RIT, although I hope soon to
    have it. However you can try some configurations. I remember one
    with suming AO. You can take it from here:
    http://www001.upp.so-
    net.ne.jp/jg1ead/allbander/e_ab.html

    Sorry also for my bad english :-(

    I have mounted a BITX15 in order to use it in 15m because I
    am "licensed C" in Spain and it work very well. I use FI of 10MHz
    and one external oscillator VXO to 31MHz. I have not mounted yet the
    power amplifier.

    However, the reception is a little weak and I added an cascode
    amplifier with two transistors and a coil in the FI. How it change!!
    Now I have the problem of excessive gain in some cases and I am
    working in an AGC.

    For the oscillator I am triying a VCO of 10 to 40MHz controlled by
    PLL 145170 and when it work I will control everything with a
    PIC16F84 with LCD and codec. Here some info:

    http://lpistor.chez.tiscali.fr/syntheblucw.htm

    I have put the diagram only for others have it like reference.
    I want to prepare a PCB more ambitious, with multiband change, CW,
    AGC, PLL and AM/ FM.

    As I have each part working I will put the schematic.
    I am not much spare time. :-(

    The BITX can work to 144MHz?? I hope so.

    Greetings
    Manuel EB7HPM/EC7ALV.


    Yahoo! Groups Sponsor
    ADVERTISEMENT
    click here


    Yahoo! Groups Links



  • ====================================
    D E E P   S P A C E   R A D I O   S Y S T E M S
    ENGINEERING SERVICES:
        *  System Design
        *  Project Planning
        *  Project Management
        *  Deployment
        *  Operation Planning & Support
    CONTACT: arvevans@...
    ====================================
                   
  • Re: PCB Parts Layout

    eb7hpm
     

    I'm sorry, but muy rig doesn't have RIT, although I hope soon to
    have it. However you can try some configurations. I remember one
    with suming AO. You can take it from here: http://www001.upp.so-
    net.ne.jp/jg1ead/allbander/e_ab.html

    Sorry also for my bad english :-(

    I have mounted a BITX15 in order to use it in 15m because I
    am "licensed C" in Spain and it work very well. I use FI of 10MHz
    and one external oscillator VXO to 31MHz. I have not mounted yet the
    power amplifier.

    However, the reception is a little weak and I added an cascode
    amplifier with two transistors and a coil in the FI. How it change!!
    Now I have the problem of excessive gain in some cases and I am
    working in an AGC.

    For the oscillator I am triying a VCO of 10 to 40MHz controlled by
    PLL 145170 and when it work I will control everything with a
    PIC16F84 with LCD and codec. Here some info:
    http://lpistor.chez.tiscali.fr/syntheblucw.htm

    I have put the diagram only for others have it like reference.
    I want to prepare a PCB more ambitious, with multiband change, CW,
    AGC, PLL and AM/ FM.

    As I have each part working I will put the schematic.
    I am not much spare time. :-(

    The BITX can work to 144MHz?? I hope so.

    Greetings
    Manuel EB7HPM/EC7ALV.