Date   
Components round 2

Hans Summers <Hans.Summers@...>
 

All components arrived here today. I have counted them all out into the
component packs and despatched them.

Note that I have two spare packs, if any latecomers would like one: price is
£8 + £0.28 UK postage, or whatever 50g costs to your country. These
components are at supplied by me at cost, from Farnell, Rapid Electronics
and Mode Components. Many are discounted due to bulk buy crystals,
transistors etc in QTY 100+. The pack comprises all semiconductors, crystals
and variable capacitors: 10x 10MHz xtals, 25x BC547B, 2N2218, IRF510, 15x
1N4148, 36V Zener, 9V1 Zener, 5V6 Zener, LM386N-1, 5x 22pF trimmer,
miniature 200pF tuning capacitor.

72/3 de Hans G0UPL
http://www.HansSummers.com

Re: Bitx 20, Help me!

Jim Strohm <jstrohm@...>
 

On Jul 2, 2004, at 10:37 AM, Arvid Evans wrote:

I first buiilt the BITX20 and am now working on a BITX40 version.
That way I can compare DC voltages and RF & AF signals with a working
unit as I complete the 40 Meter version.

Here are some changes that are being incorporated into my BITX40 as I
modify Farhan's design for 40 Meters, and to fit the contents of my
junk box
Builders are reminded that while the IRF510 final may be a little hard to find and may be a little expensive, many other power FETs will amplify quite nicely on lower frequencies, .

In the late 1980s and early 1990s, some ARRL members performed experiments with power FETs salvaged from switching power supplies. Their results as published in QST indicated that almost everything worked well at 40 meters or below.

Builders are especially reminded that IBM vastly over-engineered and de-rated power supplies for its minicomputers such as the AS/400, and a lot of those are coming onto the surplus market -- or winding up in landfills. These are EXCELLENT sources for builder parts -- with the caveat that lmost every semiconductor is marked with an IBM part number, so you'll need to bin parts as you remove them. The DIP ICs are all useless, except for use as art supplies.

I don't have a lot of experience with Hewlett-Packard minis, but most of the old 3000s, 5000s, and some 9000s should be surfacing soon, for the last gasp before the dust-bin. I **do** have a partial cross-reference for HP-numbered semiconductors, so these ARE worth hanging onto.

I'll post the list to the files section here when I find it. Alas, it's a .gif and I don't feel like typing it into a text file, and the reproduction quality is bad enough that OCR won't read it reliably.

Jim N6OTQ

HP Parts Xref

Jim <jstrohm@...>
 

I found it (surprised myself). It's now in the file section in a folder named "hp_parts_xref".
Six .gifs, all about 250K.

I found these files on the internet a few years ago and as far as I know it's fair game for
sharing with others.

It would be nice if some day this got converted to text, but since I won't start today, I
won't ask anybody else to, either!! We have things to build. I'm salvaging some PC boards
today with my hot-air gun. I think I've made about USD$3 already -- in just half an hour.

Jim N6OTQ

Resonance Calculator Tool

Arvid Evans <arvevans@...>
 

In the "files" section of this forum I have uploaded a small
spreadsheet program called "RESONANCE CALCULATOR.xls". This is a
spreadsheet program that helps calculate inductance, capacitance, or
frequency for various combinations of L and C. I found this very
handy in re-calculating the inductance values for converting Farhan's
BITX20 design into a BITX40 transceiver.

This is a Microsoft (tm) Excel spreadsheet, but if you do not have
MS-Excel all is not lost. You can go to <www.OpenOffice.org> and
download their FREE Open Office program. The spredsheet tool in Open
Office can read and execute MS-Excel programs. FYI: Open Office is
available for both MS-Windows and Linux, so if you are a Linux user
like me you now can have an equivalent of all the MS-Office tools for
FREE!

If anyone has problems with this spreadsheet, please let me know
because I can easily generate and upload both MS and OpenOffice
specific versions of this tool. If you need to "unlock" the
spreadsheet to make your own changes to the layout or formula, also
please let me know and I can provide you with the program password.

Arv - K7HKL

Re: Resonance Calculator Tool

Charles Darley
 

Hi Arv
 
Thank very much for the spread sheet ... This is something that I will  demo at the club during the sessions on the building of the project ..
 
73  Charles  G4VSZ

-----Original Message-----
From: Arvid Evans [mailto:arvevans@...]
Sent: 02 July 2004 19:45
To: BITX20@...
Subject: [BITX20] Resonance Calculator Tool

In the "files" section of this forum I have uploaded a small
spreadsheet program called "RESONANCE CALCULATOR.xls".  This is a
spreadsheet program that helps calculate inductance, capacitance, or
frequency for various combinations of L and C.  I found this very
handy in re-calculating the inductance values for converting Farhan's
BITX20 design into a BITX40 transceiver.

This is a Microsoft (tm) Excel spreadsheet, but if you do not have
MS-Excel all is not lost.  You can go to and
download their FREE Open Office program.  The spredsheet tool in Open
Office can read and execute MS-Excel programs.  FYI: Open Office is
available for both MS-Windows and Linux, so if you are a Linux user
like me you now can have an equivalent of all the MS-Office tools for
FREE!

If anyone has problems with this spreadsheet, please let me know
because I can easily generate and upload both MS and OpenOffice
specific versions of this tool.  If you need to "unlock" the
spreadsheet to make your own changes to the layout or formula, also
please let me know and I can provide you with the program password.

Arv - K7HKL


L1 and L2 on PA diagram

Charles Darley
 

Hi all

Looking at the PA diagram it is indicated that from the antenna there
are two inductors L1 and L2 but the details below indicate L4 and L5.

Can anyone confirm that L1 = L4 and L2 = L5

73 G4VSZ Charles

Re: Bitx 20, Help me!

Chris van den Berg
 

Hi,
at this moment I spend hours getting the filter working for the IF
frequency of 4.9152 MHz.
It is importand that measurements are done with the circuits
connected, it seems that the load determines the passband a lot.
To have an idea about the functioning of the filter, I connected my
LF generator to the microphone connection. Measuring the output of
Q12 (with an osciloscoop or a mw meter), you see variation of the
output level while variating the LF frequency.
For the filter I made, it learned me that my filter had some peaks
that were not close together. Playing with different capacitor
values took a lot of time but with capacitor values of 68pF, 82pF,
68pF I have peaks at 1052Hz, 1538Hz, 2000Hz (after I also corrected
the coil in the BFO to get the peaks on the right places). With a
mircophone connected, I see output while talking in the microphone.
Between the peaks, the output is not completely down but I think the
filter shape is not flat enough. This weekend, I will play with some
additional serie coils, may be the impedance of the filter is much
higher then the circuit. (I hope the peaks do not shift again ;-( ).
Anyone else suggestions?

By the way, for the ones that want to see it with an analyser: may
be the BFO signal can be connected to both mixers resulting in audio
frequency mix up, filtered and down to LF again. Then a spectrum
analyser can be used with the PC sound card? (pink noise to the
microphone terminal, output of the mixer to the LF sound card input).
Just a thought, not tried.

Lets experiment further!
Chris, PA3CRX

Please I do not have the 10MHz crystals to make the filter, but
I
have 5 pieces of 8MHz crystals with this 8MHz crystals is
possible to
make the filter with new values of resistor and capacitor?>
3) To test my crystal filter I built the BFO circuit from the
BITX20 design on a separate of circuit board and added the inductor
and variable capacitor in series with the crystal. This gave me a
very stable oscillator that could be tuned across the filter
passband
to determine the shape factor. This signal was injected into the
input of the filter and a simple diode & capacitor type RF detector
was used with my voltmeter to measure the output. I do have a
frequency counter so I was able to determine the exact frequency
that
was being output by my test oscillator. As the frequency was
varied I
was able to plot the output voltage on a sheet of grid paper. I
would
assume that you might do something similar in building your filter
using 8 MHz crystals.

Re: BAND selection

Ashhar Farhan <farhan@...>
 

one of the inherent problems with 10 MHz if is that it precludes the 10
MHz band. the IF will fall within the RF passband.

it might work if you used 14.318 MHz crystals for IF and used the 4 MHz
vfo to mix down to 10MHz IF.

You have to keep the IF, RF and VFO frequencies away from each other as
well as see to it their various (and particularly odd) multiples don't
match up.

For instance, you used a 9Mhz IF for an 18 MHz design. The second harmonic
of the BFO will appear as a tunable signal in the receiver. The VFO will
also appear as a quickly tuned spur.

W7ZOI has a program called spurtune.exe that is ideal to work these spur
resposnes out.

i am not sure about the copyrights on these programs. if they are
distributable, then i can upload them to our folders for everybody to use
them. they are very useful, all of them.

- farhan

On Sat, 3 Jul 2004, MILAREPA wrote:

Dear Forum,

Suppose I plan to have some band selection in future, after 'original' 14 MHz has been set up.

I just need confirmation about my frequency 'plan' table below,
is this correct in the meaning of 'practical' especially for 10 MHz,
that the VFO need to tune 0 ~ 0.4 MHz ?



Thanks.

BAND selection

MILAREPA <MILAREPA@...>
 

Dear Forum,
 
Suppose I plan to have some band selection in future, after 'original' 14 MHz has been set up.
 
I just need confirmation about my frequency 'plan' table below,
is this correct in the meaning of 'practical' especially for 10 MHz,
that the VFO need to tune 0 ~ 0.4 MHz ?
 
 
Thanks.

The prince of FETs

Hans Summers <Hans.Summers@...>
 

I agree with all Jim's comments about the use of FET's salvaged from PSU's
etc in power amplifiers for bands 40m or below. I always like to use
"recycled" components wherever possible.

But when it comes to higher frequency amps, the IRF510 is in my opinion the
best choice available. A month or two I was considering a highly efficient
class E amp for 30m, for a /p rig. I wondered why the IRF510 was so popular
in QRP designs. Was it just fashion? Low cost (relatively)? So I read *many*
power FET datasheets to see if there was any better alternative, at ANY
price. Gate capacitance is an issue at higher frequencies, it must be as
small as possible. Similarly fast switching times are increasingly important
at higher frequencies. For best efficiency one wants low ON resistance. And
of course high power handling capability is essential.

Unfortunately, the choice of power FET necessarily involves some compromise
of these parameters. Larger device size means lower ON resistance and higher
power dissipation, but at the expense of higher gate capacitance and thereby
also slower speed. And so on. After all my searching, I was unable to find a
device that I considered offered a more optimum compromise of these
characteristics, for an efficient QRP HF amp, than the IRF510.

It therefore appears that this is THE best FET for QRP rigs, not just a
fashion or low cost, availability etc. All the more remarkable if there is
any truth in the story that I heard, about this FET originally being
designed for use switching car indicator lights. Or is this just urban
legend? Either way, long live the prince of FET's!

72/3 de Hans G0UPL
http://www.hanssummers.com

Re: Resonance Calculator Tool

arvevans@...
 

Charles

Just to make sure that all works as anticipated in your club demo of the spreadsheet program...I have attached two versions of the spreadsheet to this email. The one with the .sxc sufix is customized for Linux and OpenOffice Spreadsheet tools. The one with the .xls suffix is my original version written using Win-98 and MS-Excel. This way you can provide copies to your club members that will fit whatever computing platform they might be using.

Please feel free to distribute this program for any non-commercial use. I had fun developing the code, so maybe someone else will have fun using it.

For your own use...the sheet protection password is my callsign (all lower-case) so now you can customize the spreadsheet to include your club logo or name. Just remember to make your changes to a "copy" of the original so that if you make a mess of it you can always return to the pure original and start over (with a new copy of the original!). 8-)

73's
Arv - K7HKL
_._

-----Original Message-----
From: Charles Darley <charles@...>
Sent: Jul 2, 2004 4:57 PM
To: BITX20@...
Subject: RE: [BITX20] Resonance Calculator Tool

Hi Arv

Thank very much for the spread sheet ... This is something that I will demo
at the club during the sessions on the building of the project ..

73 Charles G4VSZ
-----Original Message-----
From: Arvid Evans [mailto:arvevans@...]
Sent: 02 July 2004 19:45
To: BITX20@...
Subject: [BITX20] Resonance Calculator Tool


In the "files" section of this forum I have uploaded a small
spreadsheet program called "RESONANCE CALCULATOR.xls". This is a
spreadsheet program that helps calculate inductance, capacitance, or
frequency for various combinations of L and C. I found this very
handy in re-calculating the inductance values for converting Farhan's
BITX20 design into a BITX40 transceiver.

This is a Microsoft (tm) Excel spreadsheet, but if you do not have
MS-Excel all is not lost. You can go to <www.OpenOffice.org> and
download their FREE Open Office program. The spredsheet tool in Open
Office can read and execute MS-Excel programs. FYI: Open Office is
available for both MS-Windows and Linux, so if you are a Linux user
like me you now can have an equivalent of all the MS-Office tools for
FREE!

If anyone has problems with this spreadsheet, please let me know
because I can easily generate and upload both MS and OpenOffice
specific versions of this tool. If you need to "unlock" the
spreadsheet to make your own changes to the layout or formula, also
please let me know and I can provide you with the program password.

Arv - K7HKL


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Re: BAND selection

Chris van den Berg
 

I just need confirmation about my frequency 'plan' table below,
is this correct in the meaning of 'practical' especially for 10
MHz,
that the VFO need to tune 0 ~ 0.4 MHz ?
Hi,
with the filter directly connected to the antenna you are already on
10 mHz!
What is the sense of making a SSB rig for a band that alouds NO SSB?
For 10 MHz you can use the same concept with an other frequency X-tal
filter you can shape for CW use.
Good luck,
Chris,

Re: Bitx 20, Help me!

Juanjo Pastor
 

Hi Chris,

Hi,
at this moment I spend hours getting the filter working for the IF
frequency of 4.9152 MHz.
Which band are you designing it for? 4.915 is too low for 14MHz SSB and sets
the VFO tuning quite high and prone to QSY/QRH (drifting). As I have read
over there, for SSB IFs over 8MHz are better and set the VFO on lower and
more stable frequencies. Crystals between 8 and 12MHz are easy to get here
in Europe, I can get 8, 8.86, 9.83, 10, 11, 11.059 and 12 for less than 0.75
euros each, there in PA you should be also able to do so...

It is importand that measurements are done with the circuits
connected, it seems that the load determines the passband a lot.
To have an idea about the functioning of the filter, I connected my
LF generator to the microphone connection. Measuring the output of
Q12 (with an osciloscoop or a mw meter), you see variation of the
output level while variating the LF frequency.
For the filter I made, it learned me that my filter had some peaks
that were not close together. Playing with different capacitor
values took a lot of time but with capacitor values of 68pF, 82pF,
68pF I have peaks at 1052Hz, 1538Hz, 2000Hz (after I also corrected
the coil in the BFO to get the peaks on the right places). With a
mircophone connected, I see output while talking in the microphone.
Between the peaks, the output is not completely down but I think the
filter shape is not flat enough. This weekend, I will play with some
additional serie coils, may be the impedance of the filter is much
higher then the circuit. (I hope the peaks do not shift again ;-( ).
Anyone else suggestions?
A way to know the filter shape is to connect a wideband noise generator or a
wobbulator to the filter input, an AM detector (diode and capacitor) to the
output and an oscilloscope (could be a PC audio oscilloscope thru the sound
card) to the AM detector. You'll see the ripple and the bell-like shape of
the filter passband. I have seen images in the net, one of them in the site
of PY2OHH, Miguel, http://geocities.yahoo.com.br/py2ohh/ It is in portuguese
but some friends are helping them to translate the pages into english...

By the way, for the ones that want to see it with an analyser: may
be the BFO signal can be connected to both mixers resulting in audio
frequency mix up, filtered and down to LF again. Then a spectrum
analyser can be used with the PC sound card? (pink noise to the
microphone terminal, output of the mixer to the LF sound card input).
Just a thought, not tried.

Lets experiment further!
Chris, PA3CRX
I am not building the BITX, but I am enjoying this list and learning about
it anyway. All the parts but the IRF510 final amplifier are easy to get here
(and I stock most of them) so it is possible I will build it someday...

73, 72 de Juanjo, EA5CHQ-EC5ACA. EA-QRP #104, G-QRP #9742,
QRP-L #1662.

Juanjo Pastor
C/San Roque, 4-1�
46460 Silla
SPAIN

e-mail: ea5chq@...
web: http://www.ea5chq.tk
web del club: http://www.eaqrp.com
Tel.: +034 96 120 17 67
Movil: 651 35 35 11

Inductance meter

Charles Darley
 

Hi all

Saw this page whilst searching the web

http://www.web-ee.com/Schematics/Inductance%20Meter/Inductance%
20Meter.htm

It describes the construction of a simple inductance meter which is
an add on to a digital multi meter DMM. Range possible 3 micro H to
5 milli H so will be good for many of the inductors needed for the
project - to at least know that you are in the right ball park !!!

The heart of the project is just a single chip 74HC132 and a LM7805
to provide voltage regulation.

A friend is already starting the construction to day so I will leave
more feed back in due course.

Regards and 73
Charles G4VSZ

Inductance Meter

Charles Darley
 

Hi all

I note that the post has separated part of the url from the web page
mentioned - let's try again ----

www.web-ee.com/Schematics/Inductance%20Meter/Inductance%20Meter.htm

You need all without a break between Inductance% and 20Meter.htm

I hope this helps you to find the page...

Charles

BITX-xx Frequency Calculator

Arv Evans <arvevans@...>
 

A quick frequency calculation spreadsheet for the BITX-xx has been placed in the FILES section under K7HKL/BITX....

This should help resolve some of the questions regarding alternative IF Filter frequency possibilities. 

Arv - K7HKL

Re: Bitx 20, Help me!

Chris van den Berg
 

Hi Juanjo,

Which band are you designing it for? 4.915 is too low for 14MHz
SSB and sets
the VFO tuning quite high and prone to QSY/QRH (drifting). As I
have read
over there, for SSB IFs over 8MHz are better and set the VFO on
lower and
more stable frequencies.
There are more reasons for making the filter in the range 10 to 12
MHz, one for example is that lower IF x-tal ladder filters are
difficult for SSB, for CW they seems to be great.
My BITX will be for the 18 MHz band so my LO will be in the 13 MHz.
I will try a VXO, covering the whole phone band.

Crystals between 8 and 12MHz are easy to get here
in Europe,
They are also cheap available by one of the group members but (as
mentioned by one of the other group members) some persons have a
kind of brain damage that force us to use what we have. Spending
hours to get some used parts from an old PCB cost ofcourse more then
buying new but now I can say: 'I build this transceiver from scrap
and components that I had collected in the past'.
An other point of view; by using these alternatives, you learn a lot
about parameters and the circuit!
(If I do not get it working the way I want to, may be I will go to
the 10 MHz IF ;-) ).

I am not building the BITX, but I am enjoying this list and
learning about

I appreciate your comments, as mentioned above, search in your junk
box and build your own tranceiver based on the BITX20.

Chris, PA3CRX

using the BITX on RTTY

Charles Darley
 

Hi all

I was at my local radio club the other night and was discussing the
possibility of using the BITX on RTTY .. This prompted the following
responce from one of the members ...

"The elegant way for RTTY is to have a carrier, and this is shifted
for one of the tones. A small amount of capacity added across an
oscillator is the usual way, switched by the RTTY signal coming from
(say) the teleprinter contacts - or today a computer output from the
com port. This results in a purer outgoing signal than two tones into
the mike socket, as the amplitude of the tones is identical, which
does not happen when tones in the mike socket is used. (Check the
output power of the TX on mark, and then space, when using audio in
the mike. Not the same!!"

So this prompted me to look for information on the varicap ...

I came across this site :-
http://www.hanssummers.com/radio/varicap/varicap.htm

I have printed off all of the data and this will be another display
project to show members ( or have them build it and then discover )
as stated in the article "any diode is a varicap diode".

Hans I wonder if you would like to confirm one or two items which
are not clear to me...
1. that the volts into the 4060 are 12V
2. that the 14MHz xtal could be changed for one of the 10MHz xtal
already obtained ( through you ) for the project ...
3. could I / a student use ugly construction for the test project ???

This whole BITX project is enabling so many teaching side lines that
the students will not realise that they are learning so much.

73 all

Charles G4VSZ

Re: Inductance Meter

Ashhar Farhan <farhan@...>
 

the VFO of BITX20 has an interesting story. it is actually my inductance
meter!
looking at the VFO, if you removed the trimmer, it becomes a test
oscillator that iuse at all times. this idea is due to W7AAZ (Bill
Carver).
you can quickly assemble a frequency counter like one of the several shown
by Hans.
To measure an inductance, solder the the coil into the VFO circuit,
measure the frequency. The capacitance is well established, from there
calculate the inductance.
i had written a few lines code in C (i think it is posted it its entirity
on rec.radio.amateur.homebrew). that helped me calculate it quickly.
the test oscillator also works as acrystal oscillator (solder a crystal
in place of the coil) to measure and match the crystals.

- farhan

On Sun, 4 Jul 2004, Charles wrote:

Hi all

I note that the post has separated part of the url from the web page
mentioned - let's try again ----

www.web-ee.com/Schematics/Inductance%20Meter/Inductance%20Meter.htm

You need all without a break between Inductance% and 20Meter.htm

I hope this helps you to find the page...

Charles





Yahoo! Groups Links




Re: Bitx 20, Help me!

Rahul Srivastava
 

Hi!
 
In order to use 4.915mhz xtals for SSB filter I suggest taking a look at SSB mods for K1
 

Or the SSB adaptor schematics of K2 rig. Both  use 4.915Mhz xtals for their discreet SSB filter.
 
73
 
Rahul VU3WJM
 

vdberghak wrote:
Hi Juanjo,

> Which band are you designing it for? 4.915 is too low for 14MHz
SSB and sets
> the VFO tuning quite high and prone to QSY/QRH (drifting). As I
have read
> over there, for SSB IFs over 8MHz are better and set the VFO on
lower and
> more stable frequencies.

There are more reasons for making the filter in the range


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