Date   

Re: Jim's questions and stability queries...

Leonard <bitx@...>
 

--- In BITX20@..., "Steve" <steve@...> wrote:

2. Dual VFO capability could make the BITX20 much more flexible.
Problem is that one VFO has to be turned OFF when the other is
being used for receive. Otherwise there is usually enough leakage
energy to interfere with incoming signals. This becomes a real
problem when Huff & Puff stabilization is used on the VFO because
H&P looses it's "lock" when you turn it off and then back on.
Maybe I'm just missing the point here. It seems like the NORCAL FCC-1
and FCC-2 fulfill everything that is being discussed here. Normally
I'm a build-it-myself person but assembling a kit fills most of those
needs for me. I've quoted part of the specs below. For about $70 you
get all of the VFO features plus a frequency readout. I've played
with a FCC-1 and it seems great. I have both of these and will
eventually incorporate them into one of my bitx's.

The NorCal FCC-2 is an add-on DDS VFO board that extends the basic
capabilities of the FCC-1 counter kit. All of the FCC-1 features have
been retained, so you won't lose them by upgrading. A lot of work has
been put into this kit to minimize power consumption and permit
battery operation for extended periods. Surface mount technology
(SMT) has been used extensively to minimize the size and weight of
the kit. The FCC-2 is peerless in its low power consumption and
flexibility.
The kit features a DC - 20MHz DDS (Direct Digital Synthesis) chip, a
shaft encoder and provides RTTY support. A new PIC microcontroller is
supplied with the kit, which adds the VFO to the basic counter
features. The VFO firmware supports 13 bands from 160m through 2m,
plus a non-specific, Direct band. There are numerous user-
programmable parameters which are stored in EEPROM for one-time setup
convenience. You can easily switch between VFO and frequency counter
modes and the DDS output will retain its frequency. You'll see later
on how we use this feature to calibrate the counter. The user-
programmable IF offsets and scale factors permit the VFO to operate
in a wide range of HF and VHF applications. The prescale feature
permits down-stream frequency multiplication or for use as a
reference source for a PLL synthesizer. The LCD displays the actual
output frequency.

Dual VFOs and Split operation are supported in the firmware, and the
FCC-2 will operate RTTY straight off your workbench. Just connect a
COM port cable and launch the software. I've used MMTTY and it works
great. You can incorporate the FCC-1/2 combination into a homebrew
rig or package them into a separate enclosure for use as a portable
test instrument. Typical current consumption for the pair is less
than 60mA. Operation is as simple as connecting a power supply.

Leonard


Jim's questions and stability queries...

Steve <steve@...>
 

2. Dual VFO capability could make the BITX20 much more flexible.
Problem is that one VFO has to be turned OFF when the other is
being used for receive. Otherwise there is usually enough leakage
energy to interfere with incoming signals. This becomes a real
problem when Huff & Puff stabilization is used on the VFO because
H&P looses it's "lock" when you turn it off and then back on.
I've made transceivers with dual VFO in the past and have either:

1: Completely screened both VFO's and RF shorted the output of the one
not in use with a diode switched large value capacitor.

or

2: Diode switched a large capacitor into the early stages of the
oscillator to send it way off frequency. Complete screening is also
advisable.

In the interest of stability, I have always left the supply ON to both
VFO's, so that when they return to normal operation, they recover
almost instantly!

Steve - G4MJW


Re: Jim's questions and stability queries...

Arv Evans
 

AH6GI

Over the past we have discussed use of PTO solutions, including dual
oscillator configurations. To avoid having to re-invent what has
already been covered, here is a list of thoughts and observations:

1. Brass Screw type PTO arrangements are disliked by some because the
knob moves in and out relative to the front panel. There are
solutions to this with some being more elegant than others. My
web site has some additional information regarding screw-thread
PTO arrangements.
<http://arvid.evans.googlepages.com/ptotuningmethods>

2. Dual VFO capability could make the BITX20 much more flexible.
Problem is that one VFO has to be turned OFF when the other is
being used for receive. Otherwise there is usually enough leakage
energy to interfere with incoming signals. This becomes a real
problem when Huff & Puff stabilization is used on the VFO because
H&P looses it's "lock" when you turn it off and then back on.

3. Both the dual VFO problem and the H&P loss of lock problems can be
alleviated by making the VFO operate on some frequency that is
heterodyned to that needed for your BITX20. This though allows
more opportunity for spurious signals from the mixing process.
Using a heterodyned VFO arrangement also solves the H&P problem
because only the usually crystal controlled heterodyne oscillator
has to be keyed. If this heterodyne oscillator is warped up or
down by a few KHz, it can serve as an RIT function and still allow
the H&P to remain locked. This solves the RIT problem with using
a H&P stabilizer


The real issue seems to be just how much more complexity you want to add
to your BITX20, and how much that will possibly degrade performance
because of introduced spurious signals. It does seem possible that the
above solutions could be assembled in well filtered and shielded
modules, which then could be attached to a BITX20.

Arv
_._





ah6gi wrote:


--- In BITX20@... <mailto:BITX20%40yahoogroups.com>,
"Leonard" <bitx@...> wrote:

The simplest, "the kit". http://www.qrpkits.com/bitx20a.html
<http://www.qrpkits.com/bitx20a.html>

If that isn't challenging enough for you, the bare boards approach
with either the Far Circuits board at
http://www.farcircuits.net/tcvrs1.htm
<http://www.farcircuits.net/tcvrs1.htm> with additional construction
help at http://golddredgervideo.com/bitx20/index.htm
<http://golddredgervideo.com/bitx20/index.htm> or the "version
3" board available through Sunil at suillakhani123@ gmail.com
If you go scratch, and even if you don't, take a look at

http://www.wa6otp.com/pto.htm <http://www.wa6otp.com/pto.htm>

This is the most amazing thing. In one inexpensive kit, WA6OTP has
incorporated stability AND a 13 kHz/turn vernier.

This picture tells the story.

http://www.wa6otp.com/PTOBUF.JPG <http://www.wa6otp.com/PTOBUF.JPG>

I don't "know" that it's stable but with the LC components close
together, it looks like a great design.

There's room in the standard A/B switch box for two of these. That
gives you a transceiver with TWO PTO's. With a digital readout, you
can "zerobeat" the PTO's visually.

de ah6gi/4

--
======================================
Web: http://K7HKL.homelinux.net
http://bitx20a.livejournal.com
http://home.earthlink.net/~arvevans/
http://www.geocities.com/k7hkl_arv/
======================================


Re: Jim's questions and stability queries...

ah6gi
 

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

The simplest, "the kit". http://www.qrpkits.com/bitx20a.html
If that isn't challenging enough for you, the bare boards approach
with either the Far Circuits board at
http://www.farcircuits.net/tcvrs1.htm with additional construction
help at http://golddredgervideo.com/bitx20/index.htm or the "version
3" board available through Sunil at suillakhani123@ gmail.com
If you go scratch, and even if you don't, take a look at

http://www.wa6otp.com/pto.htm

This is the most amazing thing. In one inexpensive kit, WA6OTP has
incorporated stability AND a 13 kHz/turn vernier.

This picture tells the story.

http://www.wa6otp.com/PTOBUF.JPG

I don't "know" that it's stable but with the LC components close
together, it looks like a great design.

There's room in the standard A/B switch box for two of these. That
gives you a transceiver with TWO PTO's. With a digital readout, you
can "zerobeat" the PTO's visually.

de ah6gi/4


Re: Jim's questions and stability queries...

Rahul Srivastava
 

Hi! Leonard,
While assembling ver3 board please make a note that IF gain has been set with BC547 devices on board. Using higher gain device may result in slight instability. Kindly adjust the 47K feedback resistor in IF amp in such case.
Looking forward to your BITX Ver3.
73
Rahul VU3WJM

Leonard <bitx@...> wrote:
--- In BITX20@..., "Greg W:-)" <onegammyleg@...> wrote:

Leonard = the Bitx junkie.

gregW:-) OH2FFY
It's a really neat circuit! It's a lot of fun to work with because I
have all of the test equipment to look at it with.

I have the input filter aligned on the version 3 board and I'll be
taking pictures and video this weekend.
Leonard






---------------------------------
Why delete messages? Unlimited storage is just a click away.


Re: Jim's questions and stability queries...

eplerkeppler
 

Yep! That's for sure.

If there ever was a national crisis and we needed someone to save us
by building a bitx, Leonard would be our man!

-- Charles WC5MC

--- In BITX20@..., "Greg W:-)" <onegammyleg@...> wrote:

Leonard = the Bitx junkie.

gregW:-) OH2FFY

========================================================================

--- In BITX20@..., "Leonard" <bitx@> wrote:
SNIP
I'm
currently building a version 3 board and will document my efforts at
http://golddredgervideo.com/kc0wox/bitxver3/bitx20version3.htm
There's not much there right now as I just started the project.
SNIP
Leonard
http://kc0wox.com


Re: Jim's questions and stability queries...

Leonard <bitx@...>
 

--- In BITX20@..., "Greg W:-)" <onegammyleg@...> wrote:

Leonard = the Bitx junkie.

gregW:-) OH2FFY
It's a really neat circuit! It's a lot of fun to work with because I
have all of the test equipment to look at it with.

I have the input filter aligned on the version 3 board and I'll be
taking pictures and video this weekend.
Leonard


Re: Jim's questions and stability queries...

Greg W:-) <onegammyleg@...>
 

Leonard = the Bitx junkie.

gregW:-) OH2FFY

========================================================================

--- In BITX20@..., "Leonard" <bitx@...> wrote:
SNIP
I'm
currently building a version 3 board and will document my efforts at
http://golddredgervideo.com/kc0wox/bitxver3/bitx20version3.htm
There's not much there right now as I just started the project.
SNIP
Leonard
http://kc0wox.com


Re: Jim's questions and stability queries...

Leonard <bitx@...>
 

I'm really looking forward to taking on this project as my
first
scratch built radio.
Thanks in advance,
Jim - AB9LM
There's some very good alternatives to building "scratch" built.

The simplest, "the kit". http://www.qrpkits.com/bitx20a.html
A very easy way to go as everything is supplied except an antenna, a
power source, a mike, and a chassis which actually is optional as it
can be ran with the board sitting on the bench. Not elegent but
functional.

If that isn't challenging enough for you, the bare boards approach
with either the Far Circuits board at
http://www.farcircuits.net/tcvrs1.htm with additional construction
help at http://golddredgervideo.com/bitx20/index.htm or the "version
3" board available through Sunil at suillakhani123@ gmail.com I'm
currently building a version 3 board and will document my efforts at
http://golddredgervideo.com/kc0wox/bitxver3/bitx20version3.htm
There's not much there right now as I just started the project. If
you go this way, be sure to get the board for the "Avala" software
defined radio also. Thats a future project of mine and I'll be
adding web material on this as I go. The 3 boards from Sunil are a
bargin at $25.00 including shipping when I bought mine.

I don't know that the available boards are a perfect solution but I
can say they are a huge step up from the total "build it myself"
route. I'm confident that with the help available on the forum here,
any board built project can suceed.

No matter which way you choose to go, here on this forum, you will
be in a large, worldwide, fraternity of hams that are ready and
willing to assist you. If you can download the videos at
http://kc0wox.com you'll find several hours of technical help
explaining and demonstrating the technical workings of the bitx.

Leonard
http://kc0wox.com


Re: Jim's questions and stability queries...

AB9LM
 

Thanks so much for the responses everyone, they've all been more than
motivating. Also special thanks to you Ashhar, for taking time out to
help thusfar.
This project does look truly unique in that I will really be able to
test every step of the way, and fully understand the very concept of
what makes a radio work. Should I encounter any problems, it seems
that it would be quite easy to identify and resolve.

Again, can't wait to get started, and really appreciate the help.

Jim AB9LM

--- In BITX20@..., "Ashhar Farhan" <farhan@...> wrote:

jim,

there would be far less stability problems if you built modular style!!
you will have better isolation and the manhattan style also provides
a ground plane for excellent stability.

that said, i think i need to clarify somethings about the PA stability
problems.

ours is an open project that is largely driven by the community of
builders
rather than
a single person or organization. hence, there is a difference
between how
issues are raised and
resolved here.

to begin with, let me say that the bitx's PA stability issues are not
serious. It is, in fact, one of the more stable power amplifier line
ups out
there. every stage has negative feedback except the power amplifier
and they
are all individually stable.

If we had mandated a single type of construction, same type of
enclosure,
power supply etc, we would have got repeatable performance from each
build.

however, ours is a different approach, a quick look at the group's photo
section will reveal that everything from altoid tin boxes to boat
anchors
have been tried as enclosures. constructions have ranged from
professionally
done PCBs to rat's nest wirings.

the most redeeming feature of bitx is every one of them finally
works. this
is not due to any particular magic of circutry, but the nature of the
project. it is one of the most well understood homebrew projects,
several
hams with years of experience like leonard, dan, arv, etc. have
worked for
days at it, understanding the nuances and making us aware of the
issues, and
solving them.

like any other open source project, you will find several people
pointing
out to issues and others solving them. that doesn't mean that this
project
has more issues than others. it is a testament to the culture of
enquiry and
elmering that ham radio has stood for.

- farhan

On Feb 8, 2008 4:15 AM, JShroomy <jshroomy@...> wrote:

Hello all.
I've been looking for such a transceiver project for a while, and
finally came across the BITX20.
So far I've found about 50% of the components needed, and getting
ready
to order the other half from mouser.
I've built several kits before including an ATS3A which were all
flawless, so I'm a pretty experienced kit builder, and not so much
a "from-scratcher".
I'm planning to build it manhattan style using the schematic from
Hendricks kits.
For now, I'm wondering if there are any RF/stability issues I might
encounter by building this in a modular fashion. I was wanting to
build
each section on its own small board, and then join them all
together as
I go along. Are there any issues w/ building this design in that
style?
Is regular hookup wire sufficient to join module connections, or is
there a benefit to using shielded rg174, etc.
I'm really looking forward to taking on this project as my first
scratch built radio.
Thanks in advance,
Jim - AB9LM



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


Jim's questions and stability queries...

Ashhar Farhan <farhan@...>
 

jim,

there would be far less stability problems if you built modular style!!
you will have better isolation and the manhattan style also provides
a ground plane for excellent stability.

that said, i think i need to clarify somethings about the PA stability
problems.

ours is an open project that is largely driven by the community of builders
rather than
a single person or organization. hence, there is a difference between how
issues are raised and
resolved here.

to begin with, let me say that the bitx's PA stability issues are not
serious. It is, in fact, one of the more stable power amplifier line ups out
there. every stage has negative feedback except the power amplifier and they
are all individually stable.

If we had mandated a single type of construction, same type of enclosure,
power supply etc, we would have got repeatable performance from each build.

however, ours is a different approach, a quick look at the group's photo
section will reveal that everything from altoid tin boxes to boat anchors
have been tried as enclosures. constructions have ranged from professionally
done PCBs to rat's nest wirings.

the most redeeming feature of bitx is every one of them finally works. this
is not due to any particular magic of circutry, but the nature of the
project. it is one of the most well understood homebrew projects, several
hams with years of experience like leonard, dan, arv, etc. have worked for
days at it, understanding the nuances and making us aware of the issues, and
solving them.

like any other open source project, you will find several people pointing
out to issues and others solving them. that doesn't mean that this project
has more issues than others. it is a testament to the culture of enquiry and
elmering that ham radio has stood for.

- farhan

On Feb 8, 2008 4:15 AM, JShroomy <@ab9lm> wrote:

Hello all.
I've been looking for such a transceiver project for a while, and
finally came across the BITX20.
So far I've found about 50% of the components needed, and getting ready
to order the other half from mouser.
I've built several kits before including an ATS3A which were all
flawless, so I'm a pretty experienced kit builder, and not so much
a "from-scratcher".
I'm planning to build it manhattan style using the schematic from
Hendricks kits.
For now, I'm wondering if there are any RF/stability issues I might
encounter by building this in a modular fashion. I was wanting to build
each section on its own small board, and then join them all together as
I go along. Are there any issues w/ building this design in that style?
Is regular hookup wire sufficient to join module connections, or is
there a benefit to using shielded rg174, etc.
I'm really looking forward to taking on this project as my first
scratch built radio.
Thanks in advance,
Jim - AB9LM



Preparing to build bitx20 ... questions.

AB9LM
 

Hello all.
I've been looking for such a transceiver project for a while, and
finally came across the BITX20.
So far I've found about 50% of the components needed, and getting ready
to order the other half from mouser.
I've built several kits before including an ATS3A which were all
flawless, so I'm a pretty experienced kit builder, and not so much
a "from-scratcher".
I'm planning to build it manhattan style using the schematic from
Hendricks kits.
For now, I'm wondering if there are any RF/stability issues I might
encounter by building this in a modular fashion. I was wanting to build
each section on its own small board, and then join them all together as
I go along. Are there any issues w/ building this design in that style?
Is regular hookup wire sufficient to join module connections, or is
there a benefit to using shielded rg174, etc.
I'm really looking forward to taking on this project as my first
scratch built radio.
Thanks in advance,
Jim - AB9LM


Re: K5DNL RF-LED Pwr Indicator

Greg Derda
 

Ken - Yep, I opened the image in another program so I could blow it up
a tad, and i see your setup - thanks! I plan to use a DDS on my next
BITX and will definitely be looking at your mod for that - thanks
again....

Greg
ki4mmm

On Feb 7, 2008, at 3:19 PM, kwroberson wrote:

Greg , Hello , I also built mine ugly style next to the RF output
coax connector and ran a single wire to the LED on the front panel.
U may be able to see mine in the photo with the cover off, its
in the back left corner. 73 Ken K5DNL

--- In BITX20@..., Greg Derda <gderda@...> wrote:
>
> Upon following Ken's (K5DNL) post about his Norcal DDS schematic
(under
> his Photos folder), I took an interest in his little LED Power
> Indicator circuit. I also couldn't help but notice how nice his
> BITX20a rig turned out, and I especially liked his front panel
(similar
> to mine ;->)!.
>
> Anyway, I whipped together a little LED Power Indicator last night,
> hooked it up, and "IT WORKS GREAT"! What a nifty little addition!
>
> I have a question though, considering that I haven't made a contact
> with the rig since this addition - do I need to shield it? I built
> mine ugly style on a little 1/2 x 1-1/2 inch PCB that is soldered
> directly to the back of the SO-238, with a two-conductor ribbon
cable
> running to the LED on the front panel. In other words, is RF going
to
> radiate from it?
>
> Thanks,
> Greg
> ki4mmm
>



Re: BAD SWITCH ???

Arv Evans
 

There seem to be multiple causes of an initial RF pulse on PTT activation.
1) AF caused by PTT switch operation
2) Voltage changes as circuits are powered up...or down
3) momentary reflections toward balanced modulator, caused by
bi-directional IF amplifiers changing direction.

In past messages several persons have indicated they have partial fixes
for some of these problems. Those individuals may point you toward
their posts, or you could search the older messages for this subject.

Arv
_._


Earl wrote:


Anyone in the group notice a quick BUMP of RF when the PTT is pushed,
then the power meter quickly returns to zero before modulation takes
place
??
Wondering if perhaps I have bad switch ?? Why the delay ??

Regards.....Earl (VA6RF)

--
======================================
Web: http://K7HKL.homelinux.net
http://bitx20a.livejournal.com
http://home.earthlink.net/~arvevans/
http://www.geocities.com/k7hkl_arv/
======================================


Re: K5DNL RF-LED Pwr Indicator

kwroberson
 

Greg , There is no RF on the wires that go to the LED only DC
The RF is filtered by the .01 cap . I worked 5 EU stations this
morning running 5 watts and a HB rotatable dipole . The mode
was JT65A weak signal software. call freq is 14076.
73 Ken K5DNL

--- In BITX20@..., Greg Derda <gderda@...> wrote:

Upon following Ken's (K5DNL) post about his Norcal DDS schematic (under
his Photos folder), I took an interest in his little LED Power
Indicator circuit. I also couldn't help but notice how nice his
BITX20a rig turned out, and I especially liked his front panel (similar
to mine ;->)!.

Anyway, I whipped together a little LED Power Indicator last night,
hooked it up, and "IT WORKS GREAT"! What a nifty little addition!

I have a question though, considering that I haven't made a contact
with the rig since this addition - do I need to shield it? I built
mine ugly style on a little 1/2 x 1-1/2 inch PCB that is soldered
directly to the back of the SO-238, with a two-conductor ribbon cable
running to the LED on the front panel. In other words, is RF going to
radiate from it?

Thanks,
Greg
ki4mmm


Re: K5DNL RF-LED Pwr Indicator

kwroberson
 

Greg , Hello , I also built mine ugly style next to the RF output
coax connector and ran a single wire to the LED on the front panel.
U may be able to see mine in the photo with the cover off, its
in the back left corner. 73 Ken K5DNL

--- In BITX20@..., Greg Derda <gderda@...> wrote:

Upon following Ken's (K5DNL) post about his Norcal DDS schematic (under
his Photos folder), I took an interest in his little LED Power
Indicator circuit. I also couldn't help but notice how nice his
BITX20a rig turned out, and I especially liked his front panel (similar
to mine ;->)!.

Anyway, I whipped together a little LED Power Indicator last night,
hooked it up, and "IT WORKS GREAT"! What a nifty little addition!

I have a question though, considering that I haven't made a contact
with the rig since this addition - do I need to shield it? I built
mine ugly style on a little 1/2 x 1-1/2 inch PCB that is soldered
directly to the back of the SO-238, with a two-conductor ribbon cable
running to the LED on the front panel. In other words, is RF going to
radiate from it?

Thanks,
Greg
ki4mmm


Re: BAD SWITCH ???

Martien <sproet01@...>
 

Hi Earl,

I did not build the Hendrix version, but I noted that my BITX has the
same. I did not investigate it, didn't think it really matters. Anyway
I guess nothing wrong with your switch.

Martien PE1BWI


BAD SWITCH ???

Earl <va6rf@...>
 

Anyone in the group notice a quick BUMP of RF when the PTT is pushed,
then the power meter quickly returns to zero before modulation takes place ??
Wondering if perhaps I have bad switch ?? Why the delay ??

Regards.....Earl (VA6RF)


K5DNL RF-LED Pwr Indicator

Greg Derda
 

Upon following Ken's (K5DNL) post about his Norcal DDS schematic (under his Photos folder), I took an interest in his little LED Power Indicator circuit. I also couldn't help but notice how nice his BITX20a rig turned out, and I especially liked his front panel (similar to mine ;->)!.

Anyway, I whipped together a little LED Power Indicator last night, hooked it up, and "IT WORKS GREAT"! What a nifty little addition!

I have a question though, considering that I haven't made a contact with the rig since this addition - do I need to shield it? I built mine ugly style on a little 1/2 x 1-1/2 inch PCB that is soldered directly to the back of the SO-238, with a two-conductor ribbon cable running to the LED on the front panel. In other words, is RF going to radiate from it?

Thanks,
Greg
ki4mmm


Re: 11 MHz Xtal Tests

g3oth <g3oth@...>
 

--- In BITX20@..., "n7ve" <dan.Tayloe@...> wrote:

Filter crystals should be matched within 10% of the filter bandwidth
for a good filter >
--- In BITX20@..., "g3oth" <g3oth@> wrote:
if anyone knows as to how I should best employ Xtals A to D in SSB
Filter positions X1 to X4 to get a good shape factor and least ripple
out of this selection

A differs from D by 76 Hz
B and C are within 20 Hz of one another roughly midway between A
and D
Many thanks Dan for your comments re the 10% BW tolerance Rule of
Thumb you quoted.

Well Xtals A to D in my case are all better than this by a factor of
4 so it looks like I should have no problems, even if they are
randomly assembled in any order.

I had wondered if there was any theoretical advantage to be gained by
choosing a particular sequence.

If not then I will probably just use A to D in order from XI to X4 if
I do not hear to the contary from anyone else before I come to
assemble them this weekend.

Thanks and 73 de Charles G3OTH