Chris van den Berg

Hi all,
- The output power of the oscillator is about 3 mw.
While measuring the output after the first mixer and increasing the
LF level until the HF output is not incresed gave the following
results (between brackets the reference numbers of Arv):
- LF output (to mixer): 1 volt pp. (1).
- Output of mixer: 0.6 volt pp. (2).
- output of Q11: 1 mw. (3)

Strange that Arv has much more power then I have on these points.
AC Signal Measurements:
1) LF: This signal becomes non-linear when the output goes above
1.4 to 1.6 volts P-P (Peak-to-Peak).
2) At the BFO Balanced Mixer with measurements taken from
the wiper of the 100 ohm potentiometer:
Varying the audio input (signal generator connected to
microphone input) causes 0 to 5.4 V P-P DSB output.
Unbalancing the mixer potentiometer causes a reading of
3.5 to 4.0 V PP with no audio input.
3) At the collector of Q11 (Tx DSB amplifier) the DSB signal
can be varied from 0 to 2 V P-P.

What I said about the 'calculated level' makes sense: if the output
power of the oscillator is about 3 mw, an expected conversion loss
of about 7 dB (likely more), the attenuator of -4dB, indeed the
measured 0.2 mw at that point looks realistic.

It also gives me a clue that I should try to make more output from
the oscillator (if I increase the 3 mw to 30 mw makes 10 dB
difference to the total output signal?).

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).
What output do others have out of the local oscillator and the stage
with the 2N2219 (or 2N2218)?

Best regards,
Chris.

Chris van den Berg

chris, in the exit of the 2n2218 (driver, correct?) is it that you
have 150mw?

Yes, I have. By the way, the transistor I use is a 2N2219 but this
makes no difference.

and in his entrance?
I will check this again. I remember that it was very little, I
remember I was suprised about the gain of the 2N2219 stage. May be I
posted it in an older message.

Are 150mw enough for exciting the irf510, to 6watts????
The IRF510 is driven by voltage. I did not make the final amp yet so
I do not know.

The voltage output of the first mixer will be measure again by me
also, I remember that almost no power output was reached at that
point. The output power (over 50 ohms) of the oscillator is about 3
mw, with a expected conversion loss of about 7 dB (likely more), the
output on the potmeter will be about 0.6 mw.

Best regards,
Chris.

Coil data for TOKO 10K type former

Rahul Srivastava

Dear Friends,

While going thru my old files I found this small text giving turns
vs inductance for TOKO coils ( Uploaded under files). This is not my
work but of an unknown person to whom I am greatful.

Table shows that abt 12 turns for the required 2uH for frontend
coils.

Hope many wanting to replace tap washers may find data useful.

73

Rahul VU3WJM

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 : /tokoturns.txt
Description : Turns vs Inductance for TOKO coils

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

http://help.yahoo.com/help/us/groups/files

Regards,

vu3wjm <vu3wjm@...>

Arvid Evans <arvevans@...>

Rahul

I just used the scope to set up levels for the best looking DSB
signal. But you are right...we probably need to specify the proper
ratio for AF versus carrier level. That would help those without
an oscilloscope to set the proper operating point by using just
a detector and a DC voltmeter.

Farhan showed us how to build the BITX, now someone needs to put
together an alignment and operating manual.

Arv - K7HKL
_._

--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:
Hi!

From what I remember from my yester years of setting the diode bal
Mod ( In my SB 102) idealy the AF signal level should be 1/10 of
carrier level. ( A thumbrule I guess).

I may be wrong but possibly we need to have a defined optimum OSC
level as well as BFO levels as these very much effect the conversion
gain/ loss.

73

Rahul VU3WJM

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

As promised, here are some measurements from my BITX40 circuit board:

AC Signal Measurements:

1) Microphone Amplifier output (Q10 collector) is 8V PP with
the input totally over-driven by my AF signal generator at
700 Hz.
This signal becomes non-linear when the output goes above
1.4 to 1.6 volts P-P (Peak-to-Peak).

2) At the BFO Balanced Mixer with measurements taken from
the wiper of the 100 ohm potentiometer:
Varying the audio input (signal generator connected to
microphone input) causes 0 to 5.4 V P-P DSB output.
Unbalancing the mixer potentiometer causes a reading of
3.5 to 4.0 V PP with no audio input.

3) At the collector of Q11 (Tx DSB amplifier) the DSB signal
can be varied from 0 to 2 V P-P.

DC Voltage Measurements:

Q10 (Microphone Amplifier):
C = 7.0 V DC
B = 2.3 V DC
E = 3.0 V DC

Q11 (Tx DSB Amplifier)
C = 7.1 V DC
B = 2.4 V DC
E = 1.7 V DC

Transistors for Q10 and Q11 are 2N2222 (FT=150 MHz),
with measured DC gain of about 150.

OK, I hope this helps.

Arv
_._

On Fri, 2004-09-10 at 18:48, py1pe@a... wrote: hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the
result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is
already low, I imagine that the audio low seje too much, but I didn't
still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

---------------------------------

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

To unsubscribe from this group, send an email to:
BITX20-unsubscribe@...

---------------------------------
Do you Yahoo!?
Yahoo! Mail Address AutoComplete - You start. We finish.

Arvid Evans <arvevans@...>

SANDRO

There is an error in the info I sent you. I apparently
transposed the voltage readings for Base & Emitter of Q10.

The correction is shown below:

DC Voltage Measurements:

Q10 (Microphone Amplifier):
C = 7.0 V DC
* B = 2.3 V DC Actually is 3.0 V DC
* E = 3.0 V DC Actually is 2.3 V DC

Q11 (Tx DSB Amplifier)
C = 7.1 V DC
B = 2.4 V DC
E = 1.7 V DC

Sorry, 8-(
Arv
_._

--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:
Hi!

From what I remember from my yester years of setting the diode bal
Mod ( In my SB 102) idealy the AF signal level should be 1/10 of
carrier level. ( A thumbrule I guess).

I may be wrong but possibly we need to have a defined optimum OSC
level as well as BFO levels as these very much effect the conversion
gain/ loss.

73

Rahul VU3WJM

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

As promised, here are some measurements from my BITX40 circuit board:

AC Signal Measurements:

1) Microphone Amplifier output (Q10 collector) is 8V PP with
the input totally over-driven by my AF signal generator at
700 Hz.
This signal becomes non-linear when the output goes above
1.4 to 1.6 volts P-P (Peak-to-Peak).

2) At the BFO Balanced Mixer with measurements taken from
the wiper of the 100 ohm potentiometer:
Varying the audio input (signal generator connected to
microphone input) causes 0 to 5.4 V P-P DSB output.
Unbalancing the mixer potentiometer causes a reading of
3.5 to 4.0 V PP with no audio input.

3) At the collector of Q11 (Tx DSB amplifier) the DSB signal
can be varied from 0 to 2 V P-P.

DC Voltage Measurements:

Q10 (Microphone Amplifier):
C = 7.0 V DC
B = 2.3 V DC
E = 3.0 V DC

Q11 (Tx DSB Amplifier)
C = 7.1 V DC
B = 2.4 V DC
E = 1.7 V DC

Transistors for Q10 and Q11 are 2N2222 (FT=150 MHz),
with measured DC gain of about 150.

OK, I hope this helps.

Arv
_._

On Fri, 2004-09-10 at 18:48, py1pe@a... wrote: hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the
result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is
already low, I imagine that the audio low seje too much, but I didn't
still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

---------------------------------

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

To unsubscribe from this group, send an email to:
BITX20-unsubscribe@...

---------------------------------
Do you Yahoo!?
Yahoo! Mail Address AutoComplete - You start. We finish.

py1pe@...

hello friends,

chris, in the exit of the 2n2218 (driver, correct?) is it that you have 150mw?
and in his entrance?
Are 150mw enough for exciting the irf510, to 6watts????
friend Arv, I use a tip of RF and a digital voltmeter to measure the rf levels.
tomorrow I will put in he/she practices your clues and thank you very much for the measures, ok!!

73 of SANDRO - PY1PE

Rahul Srivastava

Hi!

From what I remember from my yester years of setting the diode bal Mod ( In my SB 102) idealy the AF signal level should be 1/10 of carrier level. ( A thumbrule I guess).

I may be wrong but possibly we need to have a defined optimum OSC level as well as BFO levels as these very much effect the conversion gain/ loss.

73

Rahul VU3WJM

Arv Evans wrote:
SANDRO

As promised, here are some measurements from my BITX40 circuit board:

AC Signal Measurements:

1)  Microphone Amplifier output (Q10 collector) is 8V PP with
the input totally over-driven by my AF signal generator at
700 Hz.
This signal becomes non-linear when the output goes above
1.4 to 1.6 volts P-P (Peak-to-Peak).

2)  At the BFO Balanced Mixer with measurements taken from
the wiper of the 100 ohm potentiometer:
Varying the audio input (signal generator connected to
microphone input)  causes 0 to 5.4 V P-P DSB output.
Unbalancing the mixer potentiometer causes a reading of
3.5 to 4.0 V PP with no audio input.

3)  At the collector of Q11 (Tx DSB amplifier) the DSB signal
can be varied from 0 to 2 V P-P.

DC Voltage Measurements:

Q10 (Microphone Amplifier):
C = 7.0 V DC
B = 2.3 V DC
E = 3.0 V DC

Q11 (Tx DSB Amplifier)
C = 7.1 V DC
B = 2.4 V DC
E = 1.7 V DC

Transistors for Q10 and Q11 are 2N2222 (FT=150 MHz),
with measured DC gain of about 150.

OK, I hope this helps.

Arv
_._

On Fri, 2004-09-10 at 18:48, py1pe@... wrote:
hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is already low, I imagine that the audio low seje too much, but I didn't still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

Do you Yahoo!?
Yahoo! Mail Address AutoComplete - You start. We finish.

Arv Evans <arvevans@...>

SANDRO

As promised, here are some measurements from my BITX40 circuit board:

AC Signal Measurements:

1)  Microphone Amplifier output (Q10 collector) is 8V PP with
the input totally over-driven by my AF signal generator at
700 Hz.
This signal becomes non-linear when the output goes above
1.4 to 1.6 volts P-P (Peak-to-Peak).

2)  At the BFO Balanced Mixer with measurements taken from
the wiper of the 100 ohm potentiometer:
Varying the audio input (signal generator connected to
microphone input)  causes 0 to 5.4 V P-P DSB output.
Unbalancing the mixer potentiometer causes a reading of
3.5 to 4.0 V PP with no audio input.

3)  At the collector of Q11 (Tx DSB amplifier) the DSB signal
can be varied from 0 to 2 V P-P.

DC Voltage Measurements:

Q10 (Microphone Amplifier):
C = 7.0 V DC
B = 2.3 V DC
E = 3.0 V DC

Q11 (Tx DSB Amplifier)
C = 7.1 V DC
B = 2.4 V DC
E = 1.7 V DC

Transistors for Q10 and Q11 are 2N2222 (FT=150 MHz),
with measured DC gain of about 150.

OK, I hope this helps.

Arv
_._

On Fri, 2004-09-10 at 18:48, py1pe@... wrote:
hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is already low, I imagine that the audio low seje too much, but I didn't still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

Chris van den Berg

some data from my BITX17:
- very low output from the 1st mixer, 0,2 mw after the 22 ohm
resistor (one of my first messages in this group).
- after Q11 I measure about 1 mw over 50 ohm (I know that the
imprdance at that point is about 200 ohms).
- after the 2N2218, I measure about 150 mw output over 50 ohm. (the
measures voltage with an osciloscoop is 4 volt tt while whisling in
the microphone).
What do others have at this point?
Chris.

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

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the
result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB
low, I imagine that the audio low seje too much, but I didn't still
move for
not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

Arv Evans <arvevans@...>

SANDRO

What measuring capability do you have available for debugging your BITX?
Do you have an oscilloscope?
Do you have a high-impedance DC voltmeter?
Do you have an audio signal generator?
Do you have an RF signal generator?
Knowing what test equipment you have available may help me provide additional
ideas and assistance.

Microphone amplifier audio output will look distorted after you connect it to the input of the BFO mixer.  This is due to the design of the singly-balanced mixer, and is not a problem.

Later today I will make some measurements on the microphone audio levels into and out of my mike amp, and some measurement on the output of my BFO mixer.  Then I will send you an email with those measurements for comparison with what you are experiencing.

73's
Arv - K7HKL
_._

On Fri, 2004-09-10 at 18:48, py1pe@... wrote:
hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is already low, I imagine that the audio low seje too much, but I didn't still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

•  ==================================== 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: BITX20 made in brasil...!!

py1pe@...

hello Arv,

thank you for the clues
I don't have 100mw in the exit... 8 - (
I will verify all the points that you wrote, later I say the result.
the transistors are BCs549 (freq 300mhz)
I distrust the 1st mixer seriously, because the production DSB is already low, I imagine that the audio low seje too much, but I didn't still move for not knowing which the appropriate levels.
thank you and good weekend!
73 of PY1PE SANDRO

Arvid Evans <arvevans@...>

SANDRO

Without the linear amplifier stages you will only get 100 mw to 200 mw
power out of your BITX. If your power output is way below that, then
here are some places to start looking for the problem:

1) Carefully check the resistor values you used around Q13 and Q14.
If they are not correct it can cause a significant reduction in your
power output.

2) Temporarily connect a 0.1 mfd capacitor in parallel with the
various bypass capacitors. The BITX20 frequency of 14 MHz is near the
self-resonant point of some models of capacitors. Do this one
capacitor at a time, so that you will know which capacitor might be
the problem.

3) Verify that the windings of T3 are polarized correctly. Getting
this wrong will reduce your power to almost nothing. I know this from
personal experience! 8-(

4) Make sure that the BFO frequency is adjusted properly. It
should be just outside the passband of your IF filter. I adjusted
mine so that the BFO signal sets at the -20db point on the filter curve.

5) Verify that all diodes are good in both mixers. A single bad
diode can significantly reduce the transmit signal level.

6) Sometimes a transistor will not have adequate high frequency
response, but will test good on DC or low-frequency based testers.
Substitution of known good transistors might help if you think this
might be the problem. I swapped several transistors into the
circuitry until I found the best performing ones for each circuit segment.

Maybe someone who has followed Farhan's plans exactly could make DC
and AC signal level measurements for each stage of the BITX and post
those on this forum. I would do this, but I have already modified my
BITX to the point that my measurements would probably not be correct
for a 'standard' transceiver.

Arv - k7hkl
_._

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

with relationship to adjust the frequency of resonance of the
reels, QSL!

mine doubts it is the relationship of turns between primary and
secondary to
have 50ohms of entrance and also of exit.
in any way I already set up my bitx (without the PA), the reception
is good!
testing the transmission...I found the level of sign of the buffer (1st
transistor), very weak!! does anybody have notion of the normal
levels??
excuse the language...I am using electronic translation (my English is
terrible)
everything of good to all!

73! SANDRO PY1PE

py1pe@...

hello Arv and friends,

with relationship to adjust the frequency of resonance of the reels, QSL!
mine doubts it is the relationship of turns between primary and secondary to have 50ohms of entrance and also of exit.
in any way I already set up my bitx (without the PA), the reception is good! testing the transmission...I found the level of sign of the buffer (1st transistor), very weak!! does anybody have notion of the normal levels??
excuse the language...I am using electronic translation (my English is terrible)
everything of good to all!

73! SANDRO PY1PE

Re: bitx20 new member

Arvid Evans <arvevans@...>

SANDRO

Like Chris, I used 10.7 MHz IF transformers in my BITX front end.
However, there is no reason you could not use appropriate TOKO coils,
assuming that they are the proper inductance and turns ratio.

If you use generic 10.7 MHz IF transformers for a BITX front end, you
may have to remove the internal capacitor and replace it with a
different value in order to obtain resonance at the operating frequency.

My method was to remove the internal capacitor by breaking it with a
small screwdriver. Then I lightly coupled the low-impedance winding
of that coil to my Grid Dip Meter using one turn of hookup wire. Next
I connected my "calibrated variable capacitor" to the high impedance
winding and tuned for resonance at the desired operating frequency.
At that point it was easy to read the dial on my calibrated capacitor
to find the approximate value of fixed capacitor that was necessary
for the actual circuit.

This same procedure works fine for resonating ferrite cored toroids,
and for Farhan's air-cored toroids using tap-washer formers.

Gook luck with your BITX transceiver.

Arv - K7HKL
_._

--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:
Hello Sandro,
I am not quit sure that I understand what you ask but I will give it
a try.
In the 'photos' category, I posted a schematic of what I made for
the BITX17. I have seen also a photo for the BITX40.
One of the previous postings explained how I did it.
In general: remove the capacitor, solder a capacitor to the coil
connections, solder a coupling link to the smaller windings of the
transformer and use a dip meter to find out the frequency.
Try some capacitors to get it on frequency, fine tuning can be done
with the core after final assembly.
The coupling windings in the trafo are used as input/output
connection of the filter.
Good luck and don't forget to share the results with us ;-)
Best regards,
Chris.

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

am I building my BITX20 and would it like to use in the front-
end reels
of FI of the toko, would anybody have the data for the
construction?
thank you!

SANDRO - PY1PE

Re: bitx20 new member

Chris van den Berg

Hello Sandro,
I am not quit sure that I understand what you ask but I will give it
a try.
In the 'photos' category, I posted a schematic of what I made for
the BITX17. I have seen also a photo for the BITX40.
One of the previous postings explained how I did it.
In general: remove the capacitor, solder a capacitor to the coil
connections, solder a coupling link to the smaller windings of the
transformer and use a dip meter to find out the frequency.
Try some capacitors to get it on frequency, fine tuning can be done
with the core after final assembly.
The coupling windings in the trafo are used as input/output
connection of the filter.
Good luck and don't forget to share the results with us ;-)
Best regards,
Chris.

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

am I building my BITX20 and would it like to use in the front-
end reels
of FI of the toko, would anybody have the data for the
construction?
thank you!

SANDRO - PY1PE

Re: Mixer question

Arv Evans <arvevans@...>

Jay

Trifilar-wound transformers (both toroid cored and air-cored) are a bit different from traditional
magnetically coupled transformer designs.  In a trifilar-wound transformer the windings
function as a ' transmission line ' and thus need an evenly distributed capacitive and magnetic
coupling between the wires that make up a transmission line segment of the winding.
Twisting the wires before placing then on the core makes that happen.

While it might work to 'braid' the wires, you would probably need to build a test circuit with
some fairly sophisticated test gear to verify that the new transformer was actually providing
the transmission-line function, and that the impedance transformations were the same as
those obtained using twisted conductors. I am having a hard time visualizing what the
magnetic fields would look like for a set of 'braided' conductors!

However, there might also be an easier way to evaluate the braided versus twisted
technique.  If you were to build up a pair of one-to-one baluns for 50 ohm impedance
(one being twisted and one being braided) and then try each individually in your
transmitter-to-antenna connection, you could get a fairly good idea of the relative
effectiveness of each method.  You would need an SWR bridge on both the input
(transmitter side) and the output (antenna side) of each transformer.  A comparison
of the indicated SWR, minimum SWR, power loss, and effect on system tuning
would be interesting to see.

This is an interesting thought.  If you build your BITX20 using 'braided' conductors in your
balun type transformers, please let us know the results.

Arv - k7hkl
_._

On Sat, 2004-09-04 at 23:35, null1969 wrote:
Hi all,
I have a quick question on the mixer transformers used in the
BITX20, I can benefit from others' experience. When I started the
trifilar winding I noticed that it is quite easy to "braid" the 3
wires together. In Farhan's website the technique describe is
to "twist" the 3 wires together at the rate of about 8 twists per
inch.
Now the question, will braiding be better, worse or no
significance? Braiding make the winding much easier and keeps the
wires tight, that is why I prefer it.
And, I have no prior experience "rolling" my own mixers. Thanks in

Regards,
Jay

#### -- -- Deep Space Radio Systems -- --         Designing for the future.

Re: bitx20 new member

Mike W <mike@...>

Greetings David, nice to have you aboard.
73 Mike, G8NXD qthr (redruth)
--

On 7 Sep 2004 at 12:03, Pedley David (South Devon Health Care NHS wrote:

Hi, I saw the circuit diagram on the internet in July and thought it
would be an ideal hf project. I have been collecting all the parts but
will not start building it until my Open University course finishes in
October, in the meanwhile I thought I would sign up and join the
group. I shall use ferrite toroids and have chart of inductance
against turns if anyone is interested. 73's David G8EMA

David Pedley
Senior Medical Devices Librarian
Torbay Hospital

tel 01803-655873

**********************************************************************
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action in reliance on its contents: to do so is strictly prohibited
and may be unlawful. Please inform us that this message has gone
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--------------------------------------------------------------------~-

Re: bitx20 new member

Ashhar Farhan <farhan@...>

On Tue, 7 Sep 2004, Mike W wrote:

Greetings David, nice to have you aboard.
73 Mike, G8NXD qthr (redruth)
--

On 7 Sep 2004 at 12:03, Pedley David (South Devon Health Care NHS wrote:

Hi, I saw the circuit diagram on the internet in July and thought it
would be an ideal hf project. I have been collecting all the parts but
will not start building it until my Open University course finishes in
October, in the meanwhile I thought I would sign up and join the
group. I shall use ferrite toroids and have chart of inductance
against turns if anyone is interested. 73's David G8EMA

David Pedley
Senior Medical Devices Librarian
Torbay Hospital

tel 01803-655873

**********************************************************************
***** This e-mail is confidential and privileged. If you are not the
disclose, copy or distribute information in this e-mail or take any
action in reliance on its contents: to do so is strictly prohibited
and may be unlawful. Please inform us that this message has gone
astray before deleting it. Thank you for your co-operation.
**********************************************************************
*****

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--------------------------------------------------------------------~-

bitx20 new member

Pedley David (South Devon Health Care NHS Trust) <david.pedley@...>

Hi, I saw the circuit diagram on the internet in July and thought it would be an ideal hf project. I have been collecting all the parts but will not start building it until my Open University course finishes in October, in the meanwhile I thought I would sign up and join the group. I shall use ferrite toroids and have chart of inductance against turns if anyone is interested.
73's
David G8EMA

David Pedley
Senior Medical Devices Librarian
Torbay Hospital

tel 01803-655873

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