Date   

Re: 6 m BITX ??

Ron Brink <pa2rf@...>
 

Thanks for the good info dear Allison,
 
Yes, in the meantime I discovered MOSFET IRF's are not most favourable candidates for a 6 m PA. The 2SC Japanes transistors are more common and most likely much easier to use.
 
About the synthesizer circuitry, in the past I have used a divider 4059 in combination with a 4046.
 
If after the VFO a hi-speed divider (e.g. 74F74 or U256) is used you can go up to the GHz range and have a rockstable vfo.
 
Disadvantage; 4059 might be diffictult to obtain and is rather expensive. Maybe someting with a couple of 4017 's (1...9 dividers) can be done.
 
73 de Ron
PA2RF
 


ajparent1 wrote:
--- In BITX20@..., "Ron" wrote:
> Hi fellow BITX-homebrewer,
> Yesterday I was browsing through some old "Electrons" (Dutch Ham
> magazine) and found an interesting article in which it was told that
> our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
> work on 50 MHz ! I am surprised by this. The article did not show
> fixed designs, so maybe it is just wishfull thinking...
> According to the article, achievable power levels should less lower
> than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
> Anybody experience in this field ?

To drive the input of the mosfet at 6M you will have to use very
different networks so the input capacitance can be absorbed into the
network.  Same would have to be done for output.  Major redesign
of the "linear module" is the result.  I've tried the IRF510 and
friends and they can generate fair power at 6m but they are hard to
drive and not as stable.  Devices like the 2SC1307, 2sc799, 2sc1970
and 2sc1971 are easier to use and fairly common (found in 27,mhz
US CB radios). Power out with those can be as high as 10W.

> However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
> get a (simple) rock-stable VFO.

The easiest way to get a 40mhz VFO is to take a 4mhz VFO and mix it
with a 36mhz crystal and filter the result to 40mhz.  then you get the
stability of 4mhz VFO and the required high frequency.

I'm doing it with whats called a sampling tracking PLL.   Simpler
than a full digital PLL and somewhat less trouble with spurs and
sidebands. Tuning between the digital steps is by varying the VXO
used in the down conversion osc.  It allows me to use older PLL
chips that have /n counter that only count to 255 or maybe 512.


Allison
KB1GMX




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Re: Nobody is interested in PLL?

Arv Evans <arvevans@...>
 

Allison, & others...

Since the time constant in an H&P (Huff and Puff) stabilizer is usually much
longer than that of a traditional PLL, a PIC-based H&P design might be quite
easy to implement. I wonder about the posibility of using the PIC H&P as a
slow tuning PLL-like unit where the PIC would control frequency over the full
tuning range. With such a design the operator might enter a frequency via
the keypad and the PIC would take over and slowly tune the VFO to the
requested frequency. "Slow" here being a relative term that could be quite
fast if a lookup table were employed for gross settings of the DC offset for
particular frequencies.

One big advantage of using a PIC for frequency display is that VFO offsets are
easy to accomodate (i.e. the display can show the operating frequency,
although the actual VFO may be on some other frequency as in superheterodyne
designs). This also works for LSB-CW-USB offsets of the BFO frequency.

This use of a PIC (or any other micro-controller) as a H&P control element is
something that might be best discussed in the context of the Huff & Puff VFO
forum at <http://groups.yahoo.com/group/HuffPuffVFO/>.

Arv K7HKL
_._

On Tuesday 19 July 2005 06:51 am, ajparent1 wrote:
--- In BITX20@..., Jim Strohm <jstrohm@e...> wrote:
> On Jul 10, 2005, at 7:04 AM, Ashhar Farhan wrote:
> > while PLL chips are difficult to find, the 16F84 or the 16F628 are
> > plentiful. why can't we program the PIC to behave as a  PLL on it's 
> > own?
> >
> > the PIC timer can be used to accurately measure the oscillator 
> > frequency
> > (as normal PIC based frequency counters do) instead of displaying the
> > frequency on a display, it can (in addition) also pump a capacitor 
> > that
> > in turn is used to bias a varactor across the VFO.
> >
> > if chris and his merry band can do a single chip HnP, there is no 
> > need to
> > assume that they can't turn out a single mirochip PLL too.
>
> Given how cheap a PIC is, I think it's just a matter of time before 
> we stop using standard TTL/CMOS logic, and start programming PICs as 
> replacements.  They won't be pin-for-pin replacements, but they'll be 
> easier to locate than some of the more esoteric logic chips.
>
> A PIC PLL sounds like a fabulous project.
>
> Jim N6OTQ

Three things:

PIC is a sequential device, there are whole classes of logic solutions
that are not easily done with a sequential device. 

Using the PIC as a PLL, it could be done but even the fastest parts
are far too slow to be succiciently precise.  With PLLs a lack of
precision can be causes noise in the signal.  The core of most PLLs
is the phase detector which is usually a very fast sequential logic
element to in real time compare the phse of two signals.  Hard to do
well enough with a PIC.

Using a PIC for HnP and display, this is very do able.

Allison
KB1GMX





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Re: building filters

ajparent1 <kb1gmx@...>
 

Within the base ladder filter topology there are subgoups of type.
They can designed as minimum loss, butterworth, linear phase or
Chebychev not unlike LC filters. Each has it's differences and
sailent characteristics. When designing any of these filter the
meaurement of the crystals used is important for the result to be
close to the design prediction. Measurement includes frequency,
motional L, motional C, holder C and Q. All interact. Using 4
crystals of the same type and frequency does not assure the builder
the expected result though usually it will be close. Once the
crystals are known and a design selected the termination impedence
will also be a factor. That is one design criteria, the filters
sensitivity to termination.

When I select crystals from a group of the same lot I often find
besides frequency variation some units that have significantly
different Q [usually inferior] to the rest of the lot. The
variations can be as great as 3:1. An inferior crystal such as
that will be acceptable in an oscillator but would degrade a filter
if used in one.

While this is not meant to be exhaustive by any means. It helps
explain why theory and result will be dissimilar.


Allison
KB1GMX

--- In BITX20@..., "Ruud Jongeling" <pe2bs@t...> wrote:
Hi Paul and Max,

Thanks for your info about the design of a ladderfilter. The
ladderfilter was subject in this group before. Building the BITX20 I
made a shape of the ladderfilter with the program SpectrumAnalyzer
(see also msg 460: "Shape of Ladderfilter easy to measure" by Chris
v.d. Berg). I noticed some differences between the theory and the
actual shape of the filter, see the pictures in the Photo-box and the
messages about them.

From Chris I received an article from G3JIR in QST nov. 80 about
Ladder Filter Design. A copy is dropped in the Files-box. The filters
discribed looks like the filters in the Russian program Max put in
the File-box. I am working on a 9MHz filter following the steps G3JIR
discribed. With the SpectrumAnalyzer it is not difficult to measure
the bandwith of the filters and Excel can calculate the impedance of
the filters and the C's in the filters.

Doing the measurements I noticed that matching the impedance is very
important for the filtershape. Changing the C's makes great impedance
changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching the
impedance in the amplifierstages in the BITX20 (msg 868). I am still
waiting for a reply....

When I completed the design of the filter I will drop the info in the
Files-box and the shape pictures Photo-box. I hope you will drop
pictures of your filtershapes too.

73

Ruud.






--- In BITX20@..., "Max" <m_orwell@y...> wrote:
de 4N1ZM

I added older easier for understanding version of ladder filter
desingn program in file section under 4N1ZM folder.

--- In BITX20@..., "Max" <m_orwell@y...> wrote:
de 4N1ZM

There is two programs and alternative aproach to ladder filter
design.
Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:

http://www.qrz.ru/schemes/contribute/technology/crystal/


--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
That is a good starting point but I'd add much has been
published
since then on building crystal filters.

Using the series ladder design and the right constants you can
build
USB and LSB filters as well as symetrical. A good source is
the
ARRL
publication Experimental Methods in RF Design which devotes a
fair
amount of text to crystal filters and has a good listing of
citings
for further reference.

I've use their techniques to build excellent filters using 6
and
8
crystals with symetrical shapes to greater than 70db and low
ripple.
The gausian to 6db shape happens to sound the best to me for
2.2khz
SSB filters. I'm using a 6 crystal version of same in the
first
version of BITx I've built as an transverter IF.

Allison
KB1GMX


Re: Nobody is interested in PLL?

ajparent1 <kb1gmx@...>
 

--- In BITX20@..., Jim Strohm <jstrohm@e...> wrote:

On Jul 10, 2005, at 7:04 AM, Ashhar Farhan wrote:

while PLL chips are difficult to find, the 16F84 or the 16F628 are
plentiful. why can't we program the PIC to behave as a PLL on it's
own?

the PIC timer can be used to accurately measure the oscillator
frequency
(as normal PIC based frequency counters do) instead of displaying the
frequency on a display, it can (in addition) also pump a capacitor
that
in turn is used to bias a varactor across the VFO.

if chris and his merry band can do a single chip HnP, there is no
need to
assume that they can't turn out a single mirochip PLL too.
Given how cheap a PIC is, I think it's just a matter of time before
we stop using standard TTL/CMOS logic, and start programming PICs as
replacements. They won't be pin-for-pin replacements, but they'll be
easier to locate than some of the more esoteric logic chips.

A PIC PLL sounds like a fabulous project.

Jim N6OTQ

Three things:

PIC is a sequential device, there are whole classes of logic solutions
that are not easily done with a sequential device.

Using the PIC as a PLL, it could be done but even the fastest parts
are far too slow to be succiciently precise. With PLLs a lack of
precision can be causes noise in the signal. The core of most PLLs
is the phase detector which is usually a very fast sequential logic
element to in real time compare the phse of two signals. Hard to do
well enough with a PIC.

Using a PIC for HnP and display, this is very do able.

Allison
KB1GMX


Re: building filters

Ruud Jongeling <pe2bs@...>
 

Hi Paul and Max,

Thanks for your info about the design of a ladderfilter. The
ladderfilter was subject in this group before. Building the BITX20 I
made a shape of the ladderfilter with the program SpectrumAnalyzer
(see also msg 460: "Shape of Ladderfilter easy to measure" by Chris
v.d. Berg). I noticed some differences between the theory and the
actual shape of the filter, see the pictures in the Photo-box and the
messages about them.

From Chris I received an article from G3JIR in QST nov. 80 about
Ladder Filter Design. A copy is dropped in the Files-box. The filters
discribed looks like the filters in the Russian program Max put in
the File-box. I am working on a 9MHz filter following the steps G3JIR
discribed. With the SpectrumAnalyzer it is not difficult to measure
the bandwith of the filters and Excel can calculate the impedance of
the filters and the C's in the filters.

Doing the measurements I noticed that matching the impedance is very
important for the filtershape. Changing the C's makes great impedance
changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching the
impedance in the amplifierstages in the BITX20 (msg 868). I am still
waiting for a reply....

When I completed the design of the filter I will drop the info in the
Files-box and the shape pictures Photo-box. I hope you will drop
pictures of your filtershapes too.

73

Ruud.






--- In BITX20@..., "Max" <m_orwell@y...> wrote:
de 4N1ZM

I added older easier for understanding version of ladder filter
desingn program in file section under 4N1ZM folder.

--- In BITX20@..., "Max" <m_orwell@y...> wrote:
de 4N1ZM

There is two programs and alternative aproach to ladder filter
design.
Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:

http://www.qrz.ru/schemes/contribute/technology/crystal/


--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
That is a good starting point but I'd add much has been
published
since then on building crystal filters.

Using the series ladder design and the right constants you can
build
USB and LSB filters as well as symetrical. A good source is
the
ARRL
publication Experimental Methods in RF Design which devotes a
fair
amount of text to crystal filters and has a good listing of
citings
for further reference.

I've use their techniques to build excellent filters using 6
and
8
crystals with symetrical shapes to greater than 70db and low
ripple.
The gausian to 6db shape happens to sound the best to me for
2.2khz
SSB filters. I'm using a 6 crystal version of same in the
first
version of BITx I've built as an transverter IF.

Allison
KB1GMX


R: Article about BITX20 on Italian magazine

Alessandro Santucci - I0SKK <I0SKK@...>
 

Yes Paolo,
I'm a memeber of this list and just for this reason I discovered this good
RTX and decided to show to other italian Hams... hi!

Best 73

Alex I0SKK




-----Messaggio originale-----
Da: BITX20@... [mailto:BITX20@...] Per conto di
Paolo Cravero as2594
Inviato: venerdì 8 luglio 2005 9.05
A: BITX20@...
Oggetto: [BITX20] Article about BITX20 on Italian magazine

Hi,
I just discovered that a series of 4 articles about BITX20 has been
published on the Italian magazine "RadioKit Elettronica" (03/2005 to
06/2005):

http://www.edizionicec.it/sommariomarzo.htm
http://www.edizionicec.it/sommarioaprile.htm
http://www.edizionicec.it/sommariomaggio.htm
http://www.edizionicec.it/sommariogiugno.htm

Unfortunately I am not a reader of this magazine, so I totally missed
the article and can't comment.

I wonder: is the author subscribed to this list?!?!?!?

73,
Paolo IK1ZYW

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Re: building filters

Max
 

de 4N1ZM

I added older easier for understanding version of ladder filter
desingn program in file section under 4N1ZM folder.

--- In BITX20@..., "Max" <m_orwell@y...> wrote:
de 4N1ZM

There is two programs and alternative aproach to ladder filter
design.
Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:

http://www.qrz.ru/schemes/contribute/technology/crystal/


--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can
build
USB and LSB filters as well as symetrical. A good source is the
ARRL
publication Experimental Methods in RF Design which devotes a
fair
amount of text to crystal filters and has a good listing of
citings
for further reference.

I've use their techniques to build excellent filters using 6 and
8
crystals with symetrical shapes to greater than 70db and low
ripple.
The gausian to 6db shape happens to sound the best to me for
2.2khz
SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX


Re: building filters

Max
 

de 4N1ZM

There is two programs and alternative aproach to ladder filter design.
Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:

http://www.qrz.ru/schemes/contribute/technology/crystal/

--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can build
USB and LSB filters as well as symetrical. A good source is the ARRL
publication Experimental Methods in RF Design which devotes a fair
amount of text to crystal filters and has a good listing of citings
for further reference.

I've use their techniques to build excellent filters using 6 and 8
crystals with symetrical shapes to greater than 70db and low ripple.
The gausian to 6db shape happens to sound the best to me for 2.2khz
SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX


PCB Making Kits

Jyoti P. Chakravartty <csai@...>
 

Dear Friends

I wish to let you know that VUQRP will be making "PCB Making kit"
available to VU hams who are interested in homebrewing.

The price of the kits will be around Rs.325/- plus postage or courier
charges. Very soon we will be uploading the pictures of the kits on
our vuqrp group site.

Please do get in touch with us if you are interested in getting these
kits. drop us mail at vu3bgi@...

73's

de vu3bgi


Re: Hey ;)

Hans Summers <Hans.Summers@...>
 

 
MODERATOR NOTE:
 
This message appears to be Spam - however Preethi Nair has been a member since 27-Oct-04 and in that time has only made three postings, the first two of which were radio related. I believe therefore that we do NOT have a spammer in our midst, I suspect that she has perhaps inadvertently sent out a message to everyone in her address book, which included the BITX20 forum.
 
New members please rest assured that the highest security settings are applied to this Yahoo group, such that no email addresses are accessible to non-group members, and membership requires moderator approval with a specified reason for wanting to join the BITX20 group required, before Farhan or myself approve membership.
 
73's Hans G0UPL
http://www.HansSummers.com
 

-----Original Message-----
From: Preethi Nair [mailto:preethi_nair1983@...]
Sent: 16 July 2005 10:29
To: bitx20@...
Subject: [BITX20] Hey ;)


Re: Nobody is interested in PLL?

Arv Evans <arvevans@...>
 

How about a PIC based Huff & Puff stabilized VFO that could also display the
frequency?

Arv K7HKL
_._

On Sunday 10 July 2005 09:18 am, Jim Strohm wrote:
On Jul 10, 2005, at 7:04 AM, Ashhar Farhan wrote:
> while PLL chips are difficult to find, the 16F84 or the 16F628 are
> plentiful. why can't we program the PIC to behave as a  PLL on it's 
> own?
>
> the PIC timer can be used to accurately measure the oscillator 
> frequency
> (as normal PIC based frequency counters do) instead of displaying the
> frequency on a display, it can (in addition) also pump a capacitor 
> that
> in turn is used to bias a varactor across the VFO.
>
> if chris and his merry band can do a single chip HnP, there is no 
> need to
> assume that they can't turn out a single mirochip PLL too.

Given how cheap a PIC is, I think it's just a matter of time before 
we stop using standard TTL/CMOS logic, and start programming PICs as 
replacements.  They won't be pin-for-pin replacements, but they'll be 
easier to locate than some of the more esoteric logic chips.

A PIC PLL sounds like a fabulous project.

Jim N6OTQ


YAHOO! GROUPS LINKS


 Visit your group "BITX20" on the web.
 
 To unsubscribe from this group, send an email to:
 BITX20-unsubscribe@...
 
 Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


Re: 6 m BITX ??

ajparent1 <kb1gmx@...>
 

--- In BITX20@..., "Ron" <pa2rf@y...> wrote:
Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told that
our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?
To drive the input of the mosfet at 6M you will have to use very
different networks so the input capacitance can be absorbed into the
network. Same would have to be done for output. Major redesign
of the "linear module" is the result. I've tried the IRF510 and
friends and they can generate fair power at 6m but they are hard to
drive and not as stable. Devices like the 2SC1307, 2sc799, 2sc1970
and 2sc1971 are easier to use and fairly common (found in 27,mhz
US CB radios). Power out with those can be as high as 10W.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
get a (simple) rock-stable VFO.
The easiest way to get a 40mhz VFO is to take a 4mhz VFO and mix it
with a 36mhz crystal and filter the result to 40mhz. then you get the
stability of 4mhz VFO and the required high frequency.

I'm doing it with whats called a sampling tracking PLL. Simpler
than a full digital PLL and somewhat less trouble with spurs and
sidebands. Tuning between the digital steps is by varying the VXO
used in the down conversion osc. It allows me to use older PLL
chips that have /n counter that only count to 255 or maybe 512.


Allison
KB1GMX


building filters

ajparent1 <kb1gmx@...>
 

That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can build
USB and LSB filters as well as symetrical. A good source is the ARRL
publication Experimental Methods in RF Design which devotes a fair
amount of text to crystal filters and has a good listing of citings
for further reference.

I've use their techniques to build excellent filters using 6 and 8
crystals with symetrical shapes to greater than 70db and low ripple.
The gausian to 6db shape happens to sound the best to me for 2.2khz
SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX


Re: filter design cont

ajparent1 <kb1gmx@...>
 

--- In BITX20@..., "pgdaulton" <k5wms@a...> wrote:
... have different shapes. shunt is used for Lsb series for usb.

enjoy!
PAUL DAULTON

PS HIT WRONG KEY AND SENT BEFORE MSG FINISHED
That's was a good article however there have been more written since.
The ARRL publication Experimental Methods In RF design has a far more
complete (for one place) treatment and a complete list of citationas
and references. Worth having. Also BITx traces it's origin to the
EMRFD.

FYI it's possible by selection of values to build a series filter for
either USB or LSB or even symetrical. At 6-8 crystals and symetric
shape using constants for gausian to 6db yeilds a very nice filter.


Allison


filter design

pgdaulton <k5wms@...>
 

LET ME TRY AGAIN SOMETHING HAPPENED TO FIRST MSG

THOSE OF YOU WHO ARE INTERESTED IN FILTER DESIGN PLEASE CHECK
THIS SITE. www.aade.com/filter32/dishal.htm

THE AUTHOR, JOHN PIVNICHY, WROTE AN EXCELLENT ARTICLE IN JAN1993
73 MAGAZINE DESCRIBING TWIN FILTERS FOR USB AND LSB. HE IS ALSO
THE AUTHOR OF "LADDER CRYSTAL FILTERS" PUBLISHED BY MFJ ENTERPRIZES,
STARKVILLE, MS.

THE BASIC PREMISE OF THE AUTHORS WORK IS THAT SHUNT AND SERIES FILTERS
HAVE DIFFERENT SHAPES SHUNT BEING BEST FOR LSB AND SERIES FOR USB.
HIS WORK ALSO MOVES THE FILTERS SO THAT BOTH HAVE A COMMON INTERCEPT
AND USE SINGLE CARRIER FREQ FOR BOTH.

INCLUDED IN THIS SITE IS A LINK TO FREE DOWNLOAD OF FILTER DESIGN
SOFTWARE.

ENJOY AND LEARN

PAUL DAULTON K5WMS


filter design cont

pgdaulton <k5wms@...>
 

... have different shapes. shunt is used for Lsb series for usb.

enjoy!
PAUL DAULTON

PS HIT WRONG KEY AND SENT BEFORE MSG FINISHED


filter design

pgdaulton <k5wms@...>
 

THOSE INTERESTED IN FILTR DESIGN PLEASE CHECK OUT THIS SITE
www.aade.com/filter32/dishal.htm

included in this site is a link to a filter analysis program
on the aade site.

the author of this, John Pivnichy , wrote an excellent article in Jan
1993 73Magazine and abook "Ladder Crystal Filters" published by
mfj enterprizes, Starkville MS.

The basic premise of Pivnichy's work is shunt and series filters


Re: BITX20 PCBs on Far circuits

ajparent1 <kb1gmx@...>
 

--- In BITX20@..., "eb7hpm" <msraya@t...> wrote:
--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
Two problems:

The board pattern is on the wrong side (pattern
is on top not bottom.) To use it (I may not)
the parts must be placed on foil side!
You are sure? I don't know, but if it is, what a problem!
Yes, Mr Farhan stated it as so. Minor problem. It is important
to those building to avoid runing a part.


No information on parts location on the board.
A picture of the assembled board or an overlay
would be helpful.
You can try my "manual overlay". It is located in the group files
section, here:
http://f1.grp.yahoofs.com/v1/AC_ZQpMv2RboNOk5NUi3klguYVUNm0G49XTm1P3G
pPrbXMZgXY2_vH6pqJs-e9G2bWPeL7M7n38dFFLCLpj1CpS-lP_N/BITX%20PCBs%20%
Found it!

FYI: I have one operational with many mods but not build using a PCB.
The construction is dead bug on ground plane. Works very well after mods.

The one I'm doing with FAR PCB is for 6m.

Allison


Re: noise

ajparent1 <kb1gmx@...>
 

I do not speak Dutch so translation may be needed.

One things I note is that the balanced modulator is not
terminated for AF of the RF side (going to the IF) and
marginal bypass for RF at the audio port.

Several people suggest and testing on mine confirms:

Provide DC and low RF bypass fro balanced modulator:
22uH choke (10-47uH ok) from balance resistor to ground.

Bypass RF into audio:
22uH choke (10 to 500uH ok) inserted from the junction
of .001uF to the intersection of capacitors from Q4 and Q10.
Add .001uF capacitor from the junction of the capacitors
from Q4 and Q10 to ground.

Thses changes prevent wideband (audio through RF) noise from
the IF amplifier from passing all the way to the audio amplifier
Q4.

Allison
KB1GMX


--- In BITX20@..., pe1abe <pe1abe@p...> wrote:
Hallo Cris potmeter regelt het audio prima maar als ik deze helemaal
los draai komt er veel ruis uit de luidspreker dit komt door
transistor q4.Als ik ic1 alleen spanning geef heb ik dat niet.Als ik
q4 ook spanning geef krijg ik die ruis (de rest van de schakeling heb
ik dan spannings loos)Het audio niveau zou ook wel iets hoger kunnen
naar mij idee.

----- Original Message -----
From: vdberghak
To: BITX20@...
Sent: Saturday, July 09, 2005 1:22 PM
Subject: [BITX20] Re: noise


Arjan,
I do not understand what you ask. You may try it in the Dutch
language.
Ik begrijp dat je vraagt of het normaal is dat er veel ruis uit de
ontvanger komt. Aan je vraagstelling maak ik op dat je dit niet
normaal
vindt. Waarom zou dat niet normaal zijn? Als je aan de volume
potmeter
draait, varieert dan ook het volume? Neem anders deel voor deel
los om
vast te stellen waar de ruis ontstaat. Met vriendelijke groet,
Chris.

--- In BITX20@..., "Arjan" <pe1abe@p...> wrote:
> I have a question I the reception rx working of my BITX20 only I
> well many noise on my audio this normal? can someone help me?
> greeting Arjan pe1abe




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Re: BITX20 PCBs on Far circuits

eb7hpm
 

--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
Two problems:

The board pattern is on the wrong side (pattern
is on top not bottom.) To use it (I may not)
the parts must be placed on foil side!
You are sure? I don't know, but if it is, what a problem!


No information on parts location on the board.
A picture of the assembled board or an overlay
would be helpful.
You can try my "manual overlay". It is located in the group files
section, here:
http://f1.grp.yahoofs.com/v1/AC_ZQpMv2RboNOk5NUi3klguYVUNm0G49XTm1P3G
pPrbXMZgXY2_vH6pqJs-e9G2bWPeL7M7n38dFFLCLpj1CpS-lP_N/BITX%20PCBs%20%
28Printed%20Circuit%20Boards%29/bitx_component_placing.jpg

Good bitxing...
73s
Manuel
EB7HPM/EC7ALV