Date   
Re: First Contact

Jim Kortge <jokortge@...>
 

padmanabhan cattamanchi wrote:
Congrats Jim,
Congratulations on the first qso with the BITX20.
I remember how excited we were when we first
tried out the BITX prototype in my Shack. The first
station was a German. We had worked 20 prefixes from
Europe within a week on a single IRF510 running
5 watts.
73's
paddy
vu2pep
Paddy,

Thanks for your nice email. It was quite a surprise to work some DX as the first contact on the BITX20. BTW, for those who don't know, this rig is using an 11 MHz crystal filter and a lowered VFO to match. Seems very stable and no problems with WWV time signal pickup. Also, the MDS measures at -123.8 dBm, about 0.14 microvolts, so it hears very well.

72 and kind regards,

Jim, K8IQY

Re: First Contact

padmanabhan cattamanchi
 

Congrats Jim,

Congratulations on the first qso with the BITX20.
I remember how excited we were when we first
tried out the BITX prototype in my Shack. The first
station was a German. We had worked 20 prefixes from
Europe within a week on a single IRF510 running
5 watts.

73's
paddy
vu2pep







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Re: First Contact

Jim Kortge <jokortge@...>
 

Ron Brink wrote:
Congratulations Jim,
A first contact with a homebrewed rig is always an exiting event!
Greetings from the Netherlands,
Ron
PA2RF
(BITX17-builder)
Ron,

Thanks for the nice email. It was a fun contact with a brand new rig.

See you on the bands with my BITX20 when all of the problems are resolved.

BTW, 17 meters is my favorite bicycle mobile band. Great contacts over the years on that band, some to the Netherlands!

73 and kind regards,

Jim, K8IQY

Re: First Contact

Ron Brink <pa2rf@...>
 

Congratulations Jim,
A first contact with a homebrewed rig is always an exiting event!
Greetings from the Netherlands,
Ron
PA2RF
(BITX17-builder)

Jim Kortge <jokortge@...> wrote:
Gang,

I happened to be listening on 20 yesterday with a prototype Hendricks BITX20
when Paul, F2YT came on the air calling CQ DX NA. I plugged in a mic, hastely
tuned up the long wire, and tail ended one of the stateside stations he had just
worked. To my surprise and delight, he came back and gave me a 5X9 report. Not
too shabby for about 5-watts peak output. I had it dialed back to make sure it
didn't distort. We're still looking at how much clean signal we can get out of
the rig

While we don't have all of the development done on the rig, we now know that it
works well enough to make contacts.

I thought this group might like to hear about the DX contact. We are getting
much closer to a final configuration.

72 and kind regards,

Jim, K8IQY





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First Contact

Jim Kortge <jokortge@...>
 

Gang,

I happened to be listening on 20 yesterday with a prototype Hendricks BITX20 when Paul, F2YT came on the air calling CQ DX NA. I plugged in a mic, hastely tuned up the long wire, and tail ended one of the stateside stations he had just worked. To my surprise and delight, he came back and gave me a 5X9 report. Not too shabby for about 5-watts peak output. I had it dialed back to make sure it didn't distort. We're still looking at how much clean signal we can get out of the rig

While we don't have all of the development done on the rig, we now know that it works well enough to make contacts.

I thought this group might like to hear about the DX contact. We are getting much closer to a final configuration.

72 and kind regards,

Jim, K8IQY

Re: Mike amp mod - Linear amp test

Arv Evans
 

Leonard

I Just got your email regarding the unintended group posting of info
regarding the microphone amplifier resistor changes. There is
probably no damage done, but some of those on the BITX Group may be a
bit confused by this information. So, I will reply here via the group
and try to explain what you and myself have been talking about off-group.

This all relates to testing on the Hendricks BITX20 Kits that are
being worked on in prototype form. Yourself, Jim Korge, & Dan Tayloe
all have noted that there was some 2nd & 3rd harmonic component of the
modulating audio coming out of the balanced modulator. Jim Korge came
up with a resistor change that significantly reduces this problem.

Since the Hendricks Kit design is quite close to original work by
Farhan, this fix may be of interest to others who are building, or
have already built, the original BITX20. The resistors in question
are the collector and emitter resistors of the microphone amplifier.
In the Hendricks Kit the collector resistor has been changed from 2K2
to 1K, and the emitter resistor has been changed from 2K2 to 390 ohms.
This change lowered the 2nd and 3rd harmonic energy by an additional
margin, enough to make sure that this part of the signal would easily
meet and exceed US FCC requirements.

I hope that explains any confusion regarding your post. This also
offers others a look into the attention to detail that is being
incorporated into this new BITX20 kit. Progress on the new kit is
going quite well. We are still fine-tuning the PCB layout and testing
to make sure that there are no unwanted surprises in the resulting kits.

So, no problem with your post. The information is of general interest
to the BITX20 group and may even allow others to improve the transmit
audio quality of Manhattan/Ugly built units as well as those built on
a PCB.

Arv
_._

--- In BITX20@..., "Leonard" <bitx@...> wrote:

Saturday I installed a mike amp mod suggested by Jim Kortge. It was
changing out the 2.2k collector resistor for a 1k and the 2.2k emitter
resistor for a 390 ohm. It seemed to lower the 2nd harmonic of the
modulation significantly. You can see a 7 minute video on the mod and
testing at http://golddredgervideo.com/bitx20/mikemod.wmv It's 21.42mb
in size.

I also ran some tests on my linear amp. You can see the tests and
results at http://golddredgervideo.com/bitx20/linearamp.wmv It's also
about 7 minutes and 25.3mb in size.

My boards are about all tested out. The next step is to put the whole
thing in a chassis and button them up for one final test, puting it on
the air.

Leonard
KC0WOX

More Group Storage Space

Arv Evans
 

QST QST QST

Yahoo has increased the File and Photo storage allocations on Yahoo Groups to 100 MB each. This means that we now have more space for these items. It may still be a good idea to be conservative on how we use this space, but now we do not have the specter of exceeding our storage allocation to worry about in the immediate future.

Arv
_._

Re: Getting ready to start building

Arv Evans
 

Martien

Thanks for pointing out the need for a low distortion audio oscillator.
I probably should have mentioned that.

My AF oscillator is an op-amp based Wien Bridge circuit with a small
incandescent lamp (#327) in the amplitude control loop (not diodes as is
common in newer Wien Bridge circuits). There are a number of on-line
references to Wien Bridge circuits. These might be a place to start if
someone is unfamiliar with this circuit:
<http://sound.westhost.com/project22.htm> or
<http://webapps.calvin.edu/~pribeiro/courses/engr332/Handouts/oscillators.pdf>

A miniature reed relay can be used to key the audio.

Arv
_._




martienrijssemus wrote:


Hello,

Just a hint: audio CW keying will work nicely but has the
disadvantage that the audio oscillator should generate a real good
sinus because all harmonics or distortion products from the audio
generator are also transmitted . That means that you are probably
not only transmitting on 700Hz but also on 1400Hz, 2100Hz and 2800Hz
and maybe cause QRM on other QSO's without even noticing if you are
not carefull in selecting the audiogenerator.

Martien
PE1BWI

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@...> wrote:

Bruce

If you insert a tone into the microphone jack, it will be
amplified and
go to the balanced modulator just like any other audio. If this
tone
was say 1 KHz, then the DSB output of the balanced modulator would
be
two frequencies of 10.001,000 and 9.999,000 MHz. Since we are
running
USB, the lower frequency would be filtered/blocked by the crystal
filter, leaving only the 10.001,000 MHz signal. If this tone were
to be
keyed, then the result would be a keyed signal on 10.001,000 MHz.
Now,
since most hams use something in the order of 700 Hz for receiving
CW,
it might be best to use that frequency for your CW insertion tone,
instead of 1 KHz.

Your VOX system will see this keyed tone as being just another
audio
input and will key the transmitter and keep it keyed as long as
you keep
sending. When you stop sending the VOX delay will time out and
the rig
will revert to receive mode. As a result you have semi-QSK but
not
full-QSK.

Arv
_._


This scheme provides a number of po

Bruce Conner wrote:

Arv

Yes, this seems to be a very cooperative group!

I *really* like the VOX as QSK idea. That is a must-add. Not
like my
list isn't big enough, but that makes life so much better.

The notion of using the tin box itself is really fun. It should
work,
the boxes do appear to be regular tin plate. I could have things
festooned around in there all over the walls. LOL. For the first
one I
may be cautious and build each section on a piece of board to
make
them easier to play with and test. But for rig #2 something more
special may be in order. Thanks for that suggestion.

Do I understand it correctly that the keyed tone will give SSB
CW?
(Why wouldn't it?) Are there any issues with people receiving
this
signal on minimalist rigs that are common in the QRP world?

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>,
arv
evans <arvid.evans@> wrote:

Bruce

If those lunch boxes are tinplate, you could probably solder
directly to
the material and maybe build you BITX on that as the substrate.
Probably not the ultimate in mechanical stability, but still in
interesting idea. I build a lot of things using galvanized roof
flashing (zinc plated iron) as the baseplate because it is a
lot
cheaper
than copper PCB material.

On my BITX40 I used keyed tone input for CW and included a VOX
circuit.
That provides semi-QSK operation. That rig also has an op-amp
based
audio filter for CW.

Part of the beauty of building your own BITX transceiver using
ugly
method is that you can easily modify it to meet your particular
operating mode and needs.

As you can see, there are a lot of persons here on the BITX20
group who
are willing to help if you have questions.

Arv
_._



Bruce Conner wrote:

Arv

I wasn't sure why improvements had been made for V.3, or if
it was
just an issue of component availability that might be easier
for
putting together a kit, or something like that. If you (or
anyone) can
enlighten me on specifics, that would be great. I sort of
enjoy the
"cheap & cheerful" coil construction on the original, and it
does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of
some sort
to narrow things down. I figured I could just have a "CW"
switch that
turned on the CWXmit tone and also the filter. Of course, if
I could
come up with a nice adjustable filter like the one on my old
Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that
I found
online. A plain metal lunchbox!
http://lunchboxes.com/metal.html <http://lunchboxes.com/metal.html>
<http://lunchboxes.com/metal.html <http://lunchboxes.com/metal.html>>
<http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>
<http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>>> I
got the regular square style and a couple of the smaller
snack boxes
too. They are just tin, about as thick as an altoids box,
but they
should make a super box for the BITX. The domed style box
has a cool
retro look that had some appeal, and maybe I'll try one of
those down
the road. Of course, these boxes could be painted in hammer
finish or
even black wrinkle finish for a real old fashiond look. :')
Reminds
me a bit of my old Heathkit "Twoer" with the handle on there
like
that.

Bruce

--- In BITX20@...
<mailto:BITX20%40yahoogroups.com> <mailto:BITX20%
40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@> wrote:

Bruce

PCB issues are mostly related to closeness of components
and lack of
shielding between sections. You should be able to avoid
this using
Manhattan/ugly construction method and spreading things
out a bit.

Many BITX have been built using both schematics, but
the "Version-3"
one
is later and supposedly would have the advantage of
improvement over
the
original schematic.

Adding CW is possible using various approaches. The
simplest is to
just
key an audio tone into the microphone input, but this
doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning
varactor is
already
there. Switching it between settings for transmit and
receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get
building on
my BITX. Which version of the schematic is really the
best one to
use? I have the one from Farhan's website (2004), and I
also
have the
"version 3" that is posted here. Just for the record,
I'd like
to add
CW and RIT to the rig eventually too, in case that
matters.

I'll be building using manhattan/ugly construction, so is
there any
reason to choose one over the other? I know the PCB
version
has some
issues, but wasn't sure if that carried over into non-PCB
construction
using the same circuit, or if I just wanted to go with
the
original.

Bruce
WB8OGK







Mike amp mod - Linear amp test

Leonard <bitx@...>
 

Saturday I installed a mike amp mod suggested by Jim Kortge. It was
changing out the 2.2k collector resistor for a 1k and the 2.2k emitter
resistor for a 390 ohm. It seemed to lower the 2nd harmonic of the
modulation significantly. You can see a 7 minute video on the mod and
testing at http://golddredgervideo.com/bitx20/mikemod.wmv It's 21.42mb
in size.

I also ran some tests on my linear amp. You can see the tests and
results at http://golddredgervideo.com/bitx20/linearamp.wmv It's also
about 7 minutes and 25.3mb in size.

My boards are about all tested out. The next step is to put the whole
thing in a chassis and button them up for one final test, puting it on
the air.

Leonard
KC0WOX

Re: Getting ready to start building

martienrijssemus <sproet01@...>
 

Hello,

Just a hint: audio CW keying will work nicely but has the
disadvantage that the audio oscillator should generate a real good
sinus because all harmonics or distortion products from the audio
generator are also transmitted . That means that you are probably
not only transmitting on 700Hz but also on 1400Hz, 2100Hz and 2800Hz
and maybe cause QRM on other QSO's without even noticing if you are
not carefull in selecting the audiogenerator.

Martien
PE1BWI



--- In BITX20@..., arv evans <arvid.evans@...> wrote:

Bruce

If you insert a tone into the microphone jack, it will be
amplified and
go to the balanced modulator just like any other audio. If this
tone
was say 1 KHz, then the DSB output of the balanced modulator would
be
two frequencies of 10.001,000 and 9.999,000 MHz. Since we are
running
USB, the lower frequency would be filtered/blocked by the crystal
filter, leaving only the 10.001,000 MHz signal. If this tone were
to be
keyed, then the result would be a keyed signal on 10.001,000 MHz.
Now,
since most hams use something in the order of 700 Hz for receiving
CW,
it might be best to use that frequency for your CW insertion tone,
instead of 1 KHz.

Your VOX system will see this keyed tone as being just another
audio
input and will key the transmitter and keep it keyed as long as
you keep
sending. When you stop sending the VOX delay will time out and
the rig
will revert to receive mode. As a result you have semi-QSK but
not
full-QSK.

Arv
_._


This scheme provides a number of po

Bruce Conner wrote:

Arv

Yes, this seems to be a very cooperative group!

I *really* like the VOX as QSK idea. That is a must-add. Not
like my
list isn't big enough, but that makes life so much better.

The notion of using the tin box itself is really fun. It should
work,
the boxes do appear to be regular tin plate. I could have things
festooned around in there all over the walls. LOL. For the first
one I
may be cautious and build each section on a piece of board to
make
them easier to play with and test. But for rig #2 something more
special may be in order. Thanks for that suggestion.

Do I understand it correctly that the keyed tone will give SSB
CW?
(Why wouldn't it?) Are there any issues with people receiving
this
signal on minimalist rigs that are common in the QRP world?

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>,
arv
evans <arvid.evans@> wrote:

Bruce

If those lunch boxes are tinplate, you could probably solder
directly to
the material and maybe build you BITX on that as the substrate.
Probably not the ultimate in mechanical stability, but still in
interesting idea. I build a lot of things using galvanized roof
flashing (zinc plated iron) as the baseplate because it is a
lot
cheaper
than copper PCB material.

On my BITX40 I used keyed tone input for CW and included a VOX
circuit.
That provides semi-QSK operation. That rig also has an op-amp
based
audio filter for CW.

Part of the beauty of building your own BITX transceiver using
ugly
method is that you can easily modify it to meet your particular
operating mode and needs.

As you can see, there are a lot of persons here on the BITX20
group who
are willing to help if you have questions.

Arv
_._



Bruce Conner wrote:

Arv

I wasn't sure why improvements had been made for V.3, or if
it was
just an issue of component availability that might be easier
for
putting together a kit, or something like that. If you (or
anyone) can
enlighten me on specifics, that would be great. I sort of
enjoy the
"cheap & cheerful" coil construction on the original, and it
does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of
some sort
to narrow things down. I figured I could just have a "CW"
switch that
turned on the CWXmit tone and also the filter. Of course, if
I could
come up with a nice adjustable filter like the one on my old
Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that
I found
online. A plain metal lunchbox!
http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>
<http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>> I
got the regular square style and a couple of the smaller
snack boxes
too. They are just tin, about as thick as an altoids box,
but they
should make a super box for the BITX. The domed style box
has a cool
retro look that had some appeal, and maybe I'll try one of
those down
the road. Of course, these boxes could be painted in hammer
finish or
even black wrinkle finish for a real old fashiond look. :')
Reminds
me a bit of my old Heathkit "Twoer" with the handle on there
like
that.

Bruce

--- In BITX20@... <mailto:BITX20%
40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@> wrote:

Bruce

PCB issues are mostly related to closeness of components
and lack of
shielding between sections. You should be able to avoid
this using
Manhattan/ugly construction method and spreading things
out a bit.

Many BITX have been built using both schematics, but
the "Version-3"
one
is later and supposedly would have the advantage of
improvement over
the
original schematic.

Adding CW is possible using various approaches. The
simplest is to
just
key an audio tone into the microphone input, but this
doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning
varactor is
already
there. Switching it between settings for transmit and
receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get
building on
my BITX. Which version of the schematic is really the
best one to
use? I have the one from Farhan's website (2004), and I
also
have the
"version 3" that is posted here. Just for the record,
I'd like
to add
CW and RIT to the rig eventually too, in case that
matters.

I'll be building using manhattan/ugly construction, so is
there any
reason to choose one over the other? I know the PCB
version
has some
issues, but wasn't sure if that carried over into non-PCB
construction
using the same circuit, or if I just wanted to go with
the
original.

Bruce
WB8OGK




[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

Re: Getting ready to start building

Bruce Conner
 

Rahul,

OK, that's what I needed to know. I've got a big bag of 3904's here,
so that's no problem. While optimal performance is nice, satisfactory
performance is just that - satisfactory. Besides, I can always build
another one of these if I feel I'm missing something.

Thanks!

Bruce

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

Hi!
Only major change in ver 3 is the 2 transistor IF amp providing
higher gain and a PCB design to go along with it.
Reason for former was, I used cheap far eastern BC547s for my BITX
that were not upto the mark hence a change in design to get higher
gain while maintaining the RC topology. Also changed the RF amp device
to one localy available CATV component as it provided better noise
figure and was highly suitable for negative feedback configration.
As for PCB I had long promised Farhan I would do a PCB for his FB
designs so it was just a personal commitment fulfilled.
My opinion original design is good enough used 2N3904s or some
high ft devices. Generic devices in words of Elektor mag TUN
transistor universal NPN may not provide optimum performance where RF
is concerned.
73
Rahul VU3WJM

Bruce Conner <bruce.conner@...> wrote:
Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Re: Getting ready to start building

Rahul Srivastava
 

Hi!
Only major change in ver 3 is the 2 transistor IF amp providing higher gain and a PCB design to go along with it.
Reason for former was, I used cheap far eastern BC547s for my BITX that were not upto the mark hence a change in design to get higher gain while maintaining the RC topology. Also changed the RF amp device to one localy available CATV component as it provided better noise figure and was highly suitable for negative feedback configration.
As for PCB I had long promised Farhan I would do a PCB for his FB designs so it was just a personal commitment fulfilled.
My opinion original design is good enough used 2N3904s or some high ft devices. Generic devices in words of Elektor mag TUN transistor universal NPN may not provide optimum performance where RF is concerned.
73
Rahul VU3WJM

Bruce Conner <bruce.conner@...> wrote:
Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of some sort
to narrow things down. I figured I could just have a "CW" switch that
turned on the CWXmit tone and also the filter. Of course, if I could
come up with a nice adjustable filter like the one on my old Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like that.

Bruce

--- In BITX20@..., arv evans <arvid.evans@...> wrote:

Bruce

PCB issues are mostly related to closeness of components and lack of
shielding between sections. You should be able to avoid this using
Manhattan/ugly construction method and spreading things out a bit.

Many BITX have been built using both schematics, but the "Version-3"
one
is later and supposedly would have the advantage of improvement over
the
original schematic.

Adding CW is possible using various approaches. The simplest is to
just
key an audio tone into the microphone input, but this doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning varactor is
already
there. Switching it between settings for transmit and receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also have the
"version 3" that is posted here. Just for the record, I'd like to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is there any
reason to choose one over the other? I know the PCB version has some
issues, but wasn't sure if that carried over into non-PCB construction
using the same circuit, or if I just wanted to go with the original.

Bruce
WB8OGK








---------------------------------
Inbox full of unwanted email? Get leading protection and 1GB storage with All New Yahoo! Mail.

Re: Getting ready to start building

Greg W:-) <onegammyleg@...>
 

Hi all

I was at IKEA yesterday looking at things to make into an enclosure.

Found some interesting things too , deep sided alluminium oven pans
and decorative indoor watering can's that had a nice rounded style
were OK.
At a nearby low-cost shop I found a stainless steel sausage smoker ,
which looked REALLY neat.

I'me still trying to find a large petty cash tin , the sides usually
fit together well and could look like a real enclosure for less than
half price of what they normally go for.

If you look around a bit you can find interesting things to make into
low cost enclosures.

gregW:-)


http://www.swdxer.co.nr/
=====================================================================

--- In BITX20@..., "Bruce Conner" <bruce.conner@...> wrote:
SNIP

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like that.

Bruce
SNIP

Re: Getting ready to start building

Arv Evans
 

Bruce

If you insert a tone into the microphone jack, it will be amplified and
go to the balanced modulator just like any other audio. If this tone
was say 1 KHz, then the DSB output of the balanced modulator would be
two frequencies of 10.001,000 and 9.999,000 MHz. Since we are running
USB, the lower frequency would be filtered/blocked by the crystal
filter, leaving only the 10.001,000 MHz signal. If this tone were to be
keyed, then the result would be a keyed signal on 10.001,000 MHz. Now,
since most hams use something in the order of 700 Hz for receiving CW,
it might be best to use that frequency for your CW insertion tone,
instead of 1 KHz.

Your VOX system will see this keyed tone as being just another audio
input and will key the transmitter and keep it keyed as long as you keep
sending. When you stop sending the VOX delay will time out and the rig
will revert to receive mode. As a result you have semi-QSK but not
full-QSK.

Arv
_._


This scheme provides a number of po

Bruce Conner wrote:


Arv

Yes, this seems to be a very cooperative group!

I *really* like the VOX as QSK idea. That is a must-add. Not like my
list isn't big enough, but that makes life so much better.

The notion of using the tin box itself is really fun. It should work,
the boxes do appear to be regular tin plate. I could have things
festooned around in there all over the walls. LOL. For the first one I
may be cautious and build each section on a piece of board to make
them easier to play with and test. But for rig #2 something more
special may be in order. Thanks for that suggestion.

Do I understand it correctly that the keyed tone will give SSB CW?
(Why wouldn't it?) Are there any issues with people receiving this
signal on minimalist rigs that are common in the QRP world?

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@...> wrote:

Bruce

If those lunch boxes are tinplate, you could probably solder
directly to
the material and maybe build you BITX on that as the substrate.
Probably not the ultimate in mechanical stability, but still in
interesting idea. I build a lot of things using galvanized roof
flashing (zinc plated iron) as the baseplate because it is a lot
cheaper
than copper PCB material.

On my BITX40 I used keyed tone input for CW and included a VOX
circuit.
That provides semi-QSK operation. That rig also has an op-amp based
audio filter for CW.

Part of the beauty of building your own BITX transceiver using ugly
method is that you can easily modify it to meet your particular
operating mode and needs.

As you can see, there are a lot of persons here on the BITX20 group who
are willing to help if you have questions.

Arv
_._



Bruce Conner wrote:

Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of some sort
to narrow things down. I figured I could just have a "CW" switch that
turned on the CWXmit tone and also the filter. Of course, if I could
come up with a nice adjustable filter like the one on my old Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>
<http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html>> I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like
that.

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@> wrote:

Bruce

PCB issues are mostly related to closeness of components and lack of
shielding between sections. You should be able to avoid this using
Manhattan/ugly construction method and spreading things out a bit.

Many BITX have been built using both schematics, but the "Version-3"
one
is later and supposedly would have the advantage of improvement over
the
original schematic.

Adding CW is possible using various approaches. The simplest is to
just
key an audio tone into the microphone input, but this doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning varactor is
already
there. Switching it between settings for transmit and receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get
building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also
have the
"version 3" that is posted here. Just for the record, I'd like
to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is
there any
reason to choose one over the other? I know the PCB version
has some
issues, but wasn't sure if that carried over into non-PCB
construction
using the same circuit, or if I just wanted to go with the
original.

Bruce
WB8OGK





Re: Getting ready to start building

Bruce Conner
 

Arv

Yes, this seems to be a very cooperative group!

I *really* like the VOX as QSK idea. That is a must-add. Not like my
list isn't big enough, but that makes life so much better.

The notion of using the tin box itself is really fun. It should work,
the boxes do appear to be regular tin plate. I could have things
festooned around in there all over the walls. LOL. For the first one I
may be cautious and build each section on a piece of board to make
them easier to play with and test. But for rig #2 something more
special may be in order. Thanks for that suggestion.

Do I understand it correctly that the keyed tone will give SSB CW?
(Why wouldn't it?) Are there any issues with people receiving this
signal on minimalist rigs that are common in the QRP world?

Bruce


--- In BITX20@..., arv evans <arvid.evans@...> wrote:

Bruce

If those lunch boxes are tinplate, you could probably solder
directly to
the material and maybe build you BITX on that as the substrate.
Probably not the ultimate in mechanical stability, but still in
interesting idea. I build a lot of things using galvanized roof
flashing (zinc plated iron) as the baseplate because it is a lot
cheaper
than copper PCB material.

On my BITX40 I used keyed tone input for CW and included a VOX
circuit.
That provides semi-QSK operation. That rig also has an op-amp based
audio filter for CW.

Part of the beauty of building your own BITX transceiver using ugly
method is that you can easily modify it to meet your particular
operating mode and needs.

As you can see, there are a lot of persons here on the BITX20 group who
are willing to help if you have questions.

Arv
_._



Bruce Conner wrote:

Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of some sort
to narrow things down. I figured I could just have a "CW" switch that
turned on the CWXmit tone and also the filter. Of course, if I could
come up with a nice adjustable filter like the one on my old Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html> I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like
that.

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@> wrote:

Bruce

PCB issues are mostly related to closeness of components and lack of
shielding between sections. You should be able to avoid this using
Manhattan/ugly construction method and spreading things out a bit.

Many BITX have been built using both schematics, but the "Version-3"
one
is later and supposedly would have the advantage of improvement over
the
original schematic.

Adding CW is possible using various approaches. The simplest is to
just
key an audio tone into the microphone input, but this doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning varactor is
already
there. Switching it between settings for transmit and receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get
building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also
have the
"version 3" that is posted here. Just for the record, I'd like
to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is
there any
reason to choose one over the other? I know the PCB version
has some
issues, but wasn't sure if that carried over into non-PCB
construction
using the same circuit, or if I just wanted to go with the
original.

Bruce
WB8OGK


[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

Re: Getting ready to start building

Arv Evans
 

Bruce

If those lunch boxes are tinplate, you could probably solder directly to
the material and maybe build you BITX on that as the substrate.
Probably not the ultimate in mechanical stability, but still in
interesting idea. I build a lot of things using galvanized roof
flashing (zinc plated iron) as the baseplate because it is a lot cheaper
than copper PCB material.

On my BITX40 I used keyed tone input for CW and included a VOX circuit.
That provides semi-QSK operation. That rig also has an op-amp based
audio filter for CW.

Part of the beauty of building your own BITX transceiver using ugly
method is that you can easily modify it to meet your particular
operating mode and needs.

As you can see, there are a lot of persons here on the BITX20 group who
are willing to help if you have questions.

Arv
_._



Bruce Conner wrote:


Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of some sort
to narrow things down. I figured I could just have a "CW" switch that
turned on the CWXmit tone and also the filter. Of course, if I could
come up with a nice adjustable filter like the one on my old Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html
<http://lunchboxes.com/metal.html> I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like that.

Bruce

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@...> wrote:

Bruce

PCB issues are mostly related to closeness of components and lack of
shielding between sections. You should be able to avoid this using
Manhattan/ugly construction method and spreading things out a bit.

Many BITX have been built using both schematics, but the "Version-3"
one
is later and supposedly would have the advantage of improvement over
the
original schematic.

Adding CW is possible using various approaches. The simplest is to
just
key an audio tone into the microphone input, but this doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning varactor is
already
there. Switching it between settings for transmit and receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also have the
"version 3" that is posted here. Just for the record, I'd like to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is there any
reason to choose one over the other? I know the PCB version has some
issues, but wasn't sure if that carried over into non-PCB construction
using the same circuit, or if I just wanted to go with the original.

Bruce
WB8OGK



Re: Getting ready to start building

Bruce Conner
 

Arv

I wasn't sure why improvements had been made for V.3, or if it was
just an issue of component availability that might be easier for
putting together a kit, or something like that. If you (or anyone) can
enlighten me on specifics, that would be great. I sort of enjoy the
"cheap & cheerful" coil construction on the original, and it does
appear to work OK.

Yes, the receiving on CW would have to kick in a filter of some sort
to narrow things down. I figured I could just have a "CW" switch that
turned on the CWXmit tone and also the filter. Of course, if I could
come up with a nice adjustable filter like the one on my old Drake
2-B, that would be super!

I'll be trying to put this into a nice metal container that I found
online. A plain metal lunchbox! http://lunchboxes.com/metal.html I
got the regular square style and a couple of the smaller snack boxes
too. They are just tin, about as thick as an altoids box, but they
should make a super box for the BITX. The domed style box has a cool
retro look that had some appeal, and maybe I'll try one of those down
the road. Of course, these boxes could be painted in hammer finish or
even black wrinkle finish for a real old fashiond look. :') Reminds
me a bit of my old Heathkit "Twoer" with the handle on there like that.

Bruce


--- In BITX20@..., arv evans <arvid.evans@...> wrote:

Bruce

PCB issues are mostly related to closeness of components and lack of
shielding between sections. You should be able to avoid this using
Manhattan/ugly construction method and spreading things out a bit.

Many BITX have been built using both schematics, but the "Version-3"
one
is later and supposedly would have the advantage of improvement over
the
original schematic.

Adding CW is possible using various approaches. The simplest is to
just
key an audio tone into the microphone input, but this doesn't do
anything to narrow the bandwidth for receiving CW.

Adding RIT seems fairly easy because the Fine Tuning varactor is
already
there. Switching it between settings for transmit and receive
should be
possible with a minimal amount of re-design.

Good luck on your BITX project.

Arv - K7HKL
_._


Bruce Conner wrote:

I'm just about set to pull all the parts together and get building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also have the
"version 3" that is posted here. Just for the record, I'd like to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is there any
reason to choose one over the other? I know the PCB version has some
issues, but wasn't sure if that carried over into non-PCB construction
using the same circuit, or if I just wanted to go with the original.

Bruce
WB8OGK


[Non-text portions of this message have been removed]

Re: Toroid source!

martienrijssemus <sproet01@...>
 

Hello all,

Just a hint that might help some of you purchasing toriods for the
mixer, balanced modulator and the driver amplifier. Try to get some
Cable TV splitters. You can purchase them at DIY stores or try to
get friendly with your local Cable guy. Anyway those splitters are
made of transmission line transformers and that is just what we
need. The ferrite beats you will find inside those splitters will
make very good transmission line transformers from 4MHz up to 1GHz.
Some of the better splitters are made of the best ferrite you can
get in the world with transformers losses at less then 0.3dB from
4MHz up to 1 GHz. I use them all the time and they work great. Dont
use too many windings though, just 6-7 will do nicely. You can use
all the beats you find inside (1-hole, 2-hole) since the form makes
no difference

Oh.. and try to get 4 ways or 6-ways, there are much more beats
inside then in a 2-way.

Martien
PE1BWI



--- In BITX20@..., Jim Strohm <n6otq@...> wrote:

Hi all

What's a good source for toroid and ferrite cores that
won't cost me an arm and a leg like Dan's Small Parts,
and won't rob me on US shipping?

I don't mind buying in bags of 100.

Some of this is for personal use, and some for
hobbyist re-distribution -- non-commercial but not
necessarily giveaways.

Thanks and 73

Jim N6OTQ



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Re: Mike amp tests

martienrijssemus <sproet01@...>
 

Hi Leonard,

One of the things you can do to improve carrier suppression is
adding an Xtall with an inductor in series to ground somewhere in
the middle of the x-tall filter. This extra x-tall acts as a very
high Q series trap which you can set exactly to the carrier
frequency thus improving carrier suppression. I did that and it
really helped a lot since the original filter steepness was not too
good at the lowfrequency site and did not add a lot to carrier
suppression in my sample.

Best regards,

Martien
PE1BWI

--- In BITX20@..., "martienrijssemus" <sproet01@...>
wrote:

Hi Leonard,

True , I see the same. But -30dBc for second order harmonic
distortion
might indeed not be that bad for a simple diode modulator so it
could
well be as good as it gets. I now mounted the emitter follower and
had
to reduce the mic. amp gain by adding an 82 Ohm resistor is series
with
the 50uF emitter decoupling cap. Second harmonic is now -30dB
down.
This should now be unnoticable to the human ear.

Martien PE1BWI


--- In BITX20@..., "Leonard" <bitx@> wrote:

2) I added an emitter follower between mic. amplifier and the
balanced modulator and noticed the second harmonic improved
from -
20dB to -30dB so it might well be that the mic.
-30db is what I was seeing when I was driveing it with the
function
generator. That may be as good as it gets using the modulator
design
that we have.
Leonard

Re: Getting ready to start building

martienrijssemus <sproet01@...>
 

Hello Bruce,

I used the original Farnell one from his website and apart from the
small mistake at the LM386 (you can find the solution in the file
section or in the datasheet which you can find at national
semiconductor website)it worked immediatly. I did not use the original
VFO but used another design with a FET (just surf the web and you will
find many suitable designs) and a "Huff and Puff" stabiliser. In the
file section I attached the schematics for the stabiliser and also the
CW module I designed and use with the BITX.

I now operate this small transceiver for some weeks and am amazed by
the performance. I especially like the receiver, such clear reception!

Good luck and lots of fun building,

Martien
PE1BWI



--- In BITX20@..., "Bruce Conner" <bruce.conner@...> wrote:

I'm just about set to pull all the parts together and get building on
my BITX. Which version of the schematic is really the best one to
use? I have the one from Farhan's website (2004), and I also have
the
"version 3" that is posted here. Just for the record, I'd like to add
CW and RIT to the rig eventually too, in case that matters.

I'll be building using manhattan/ugly construction, so is there any
reason to choose one over the other? I know the PCB version has some
issues, but wasn't sure if that carried over into non-PCB
construction
using the same circuit, or if I just wanted to go with the original.

Bruce
WB8OGK