Date   
adhésion yahoo groop Bitx 20

Bernard MOUROT
 

mes amis

merci de m'accepter dans le groupe

73

F6BCU



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Re: Out of the dustbin ...

Jim Strohm <n6otq@...>
 

--- David Snell <dgsnell@...> wrote:

But how do you smuggle it past SWMBO?
My SWMBO* is incredibly tolerant of my hobbies. Plus,
she's also professionally in high tech at least as
deeply as I am, and she understands that I learn from
the junk I bring home.

The processor module with heatsink in this instance is
about 3 inches by 7 inches, and 3 inches tall. In
metric terms, that's about the size of a 0.5 litre
beer. Only the heatsink is retained, and since it's
made of (as you spell it) aluminium it is easily
recycled at the closest hard goods store, or in the
usual WEEE electronics fashion.

Jim N6OTQ

*SWMBO = "She Who Must Be Obeyed"

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Re: Out of the dustbin ...

David Snell <dgsnell@...>
 

But how do you smuggle it past SWMBO?

Dave M1DGS

----- Original Message -----
From: Jim Strohm
To: jim.strohm@...
Sent: Wednesday, April 25, 2007 7:56 PM
Subject: [BITX20] Out of the dustbin ...


Today I happened upon an abandoned computer by the
curb, next to the dumpster.

A few moments of raiding yielded a couple of
peripheral cards (to be tested later) and an AMD
Athlon 900 processor with heatsink. This is the
slot-style processor card that was used aaround 1999 /
2000.

The heatsink is big enough that it looks like it'll
easily dissipate 80 to 100 watts. It's only suitable
for flange-mount devices that can be secured by
drilling and tapping the mounting holes from the flat
side.

Think about this source the next time you need a hefty
and cheap heatsink.

Apparently, the reason that this PC bit the dust was
-- the heatsink compound was not properly applied. It
was dried and yellowed into chunks that flaked off on
disassembly, and the PCB for the processor had some
significant heat discoloration round the processor
chip.

Jim N6OTQ

__________________________________________________
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Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.10/774 - Release Date: 23/04/2007 17:26

Out of the dustbin ...

Jim Strohm <n6otq@...>
 

Today I happened upon an abandoned computer by the
curb, next to the dumpster.

A few moments of raiding yielded a couple of
peripheral cards (to be tested later) and an AMD
Athlon 900 processor with heatsink. This is the
slot-style processor card that was used aaround 1999 /
2000.

The heatsink is big enough that it looks like it'll
easily dissipate 80 to 100 watts. It's only suitable
for flange-mount devices that can be secured by
drilling and tapping the mounting holes from the flat
side.

Think about this source the next time you need a hefty
and cheap heatsink.

Apparently, the reason that this PC bit the dust was
-- the heatsink compound was not properly applied. It
was dried and yellowed into chunks that flaked off on
disassembly, and the PCB for the processor had some
significant heat discoloration round the processor
chip.

Jim N6OTQ

__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com

Re: any kit updates?

Paul Tomlinson <m0eme432@...>
 

Yes its nice and spread out, and works a treat. The huff and puff designs I tried were by OM3CPH, EI9GQ and finally I finished with the X-LOCK from Cumbria designs. But they all worked fine, I just got the XLOCK bought me as a gift hihi so I stuck with it.
The VFO design I used was called the PORTLAND by Spectrum Communications and is a nice stable design.
I don't know how stable the XLOCK makes the VFO but the write up says 10Hz.
It seems fine decoding PSK and JT65A that appears now and again.
Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@...
Sent: Sunday, April 22, 2007 2:10 AM
Subject: Re: [BITX20] Re: any kit updates?


Paul

The beauty of modular construction like yours is that you can easily fix
things that don't work properly. I would think that you have adequate
shielding, but the real proof is in building and smoke testing it.

If you have access to a spectrum analyzer it would be interesting to
look for audio harmonics coming out of the balanced modulator on
transmit mode. Leonard KC0OWX first noticed these and as a result we
slightly modified the mike amp to clean things up a bit in that area.

In order to get clean RF output you need a clean VFO signal (minimal
harmonic content). Jim K8IQY changed things around a bit in the VFO to
improve signal quality. You may have noticed a series resonant 14 MHz
filter in the input to Q4 (new BITX20A schematic). This is primarily to
block VFO and unwanted mixer products from getting into the transmit stream.

Which H&P Stabilizer design did you use? It would be interesting to see
how many BITX builders are using some variation of the H&P design
(Klaas' original design, variations on Klaas' design, G0UOPL's 2-chip
version, FAST H&P version, etc.). It is really nice to have that +/-
1Hz stability if you are going to run PSK or something like that with
your BITX rig.

http://www.hanssummers.com/radio/huffpuff/index.htm

http://groups.yahoo.com/group/HuffPuffVFO/

Arv
_._

Paul Tomlinson wrote:
>
> Thanks Arv, I was going to do that anyway. I've got a different VFO
> design and a Huff-Puff stabiliser working nicely in a diecast box. The
> PA is in another diecast box, and so I was going to fit what's left on
> a small PCB. I was also going to fit 25mm walls around all the various
> sections, and probably put the CO in a small metal box also. Do you
> think this is enough?
> Paul M0EME
>
> ----- Original Message -----
> From: arv evans
> To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> Sent: Saturday, April 21, 2007 9:45 PM
> Subject: Re: [BITX20] Re: any kit updates?
>
> Paul
>
> You can use close spacing in a non-PCB layout if you put in shielding
> between stages. The VFO and RF PA sections need their own shielded
> enclosures. The problem we ran into with a compact PCB layout is that
> it is quite hard to do such shielding without resorting to custom
> fabricated shielding plates that would mount on the PCB. The expense of
> doing this sort of defeats the idea of keeping the kit cost to a minimum.
>
> Arv
> _._
>
> Paul Tomlinson wrote:
> >
> > Thankyou for the reply, I'm glad you sent it to be honest. I've got a
> > working version on my bench now, but wanted to miniaturise it to fit a
> > nice old CB radio box I've kept for such a project. But now you speak
> > of instability problems caused by close spacing. So I better stop the
> > layout I'm doing and wait to see yours.
> > Thanks Paul M0EME
> >
> > ----- Original Message -----
> > From: arv evans
> > To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> <mailto:BITX20%40yahoogroups.com>
> > Sent: Saturday, April 21, 2007 7:48 PM
> > Subject: Re: [BITX20] Re: any kit updates?
> >
> > Paul
> >
> > Sorry about that. The Q-26 part exists in a new PCB based kit layout
> > for the BITX20.
> >
> > We (Dan N7VE, Jim K8IQY, Doug KI6DS, and myself) are working on a new
> > kit layout for the BITX20A. While that kit is not yet available, some
> > members of the BITX20 group have been participating in discussions and
> > commenting on our design re-work effort. This is where the strange
> > component designations are coming from.
> >
> > Making a parts and PCB kit available for the BITX20 eliminates some of
> > the parts restrictions that Farhan faced with his initial BITX design.
> > Designing a very compact PCB layout for the BITX20A required some
> > circuit re-design to avoid instability caused by close spaced
> > components. Keeping the kit cost as low as possible causes a new set
> > of parts restrictions and required some changes to allow utilization of
> > easily purchased and low cost components. Since the kit will be
> > marketed in the United States, it must be rigorously tested and must
> > comply with our FCC (Federal Communications Commission) rules for
> > spectral purity and stability.
> >
> > All of these situations have caused us to build and evaluate two
> > prototype layouts. We are just now starting on the third prototype
> > build. Hopefully this will be the final prototype evaluation and will
> > result in a production run for the actual kit.
> >
> > Schematics and other information for our kit building effort may be
> > found at the following web blog addresses (scroll back in time on the
> > first blog in order to find the schematics for Version 1.1 and version
> > 1.0):
> >
> > http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>
> <http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>>
> >
> > http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>
> <http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>>
> >
> > The Q-26 that you questioned shows up as part of the T/R switching
> > arrangement in the last blog. This set of blogs show the evolution that
> > we have gone through to arrive at a workable and compact PCB & parts kit
> > for the BITX20A design. I have used the BITX20A designation to indicate
> > that the kit design is a bit different from Farhan's original layout,
> > but that it still follows the technical intent of his original design.
> >
> > I hope that clears up the confusion about apparently non-existing parts.
> >
> > Arv - K7HKL
> > _._
> >
> > Paul Tomlinson wrote:
> > >
> > > help me please, I'm confused. In my version 3 pcb layout that I have
> > > build my Bitx20 from, there are only 15 transistors, so where does Q26
> > > come from?
> > >
> > > ----- Original Message -----
> > > From: Warren McRobie
> > > To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> <mailto:BITX20%40yahoogroups.com>
> > <mailto:BITX20%40yahoogroups.com>
> > > Sent: Saturday, April 21, 2007 1:09 AM
> > > Subject: Re: [BITX20] Re: any kit updates?
> > >
> > > Looking over the latest circuit, looks really good.
> > >
> > > One thing puzzles me tho - Q 26 should be on during receive not
> transmit
> > > - or am I missing something?
> > >
> > > Doug, Arv and the other proto builders are doing Amateur Radio a great
> > > service.
> > >
> > > Cannot wait for the kit to be ready.
> > >
> > > Warren
> > > ZL3LC
> > >
> > > ----------------------------------------------------------
> > >
> > > No virus found in this incoming message.
> > > Checked by AVG Free Edition.
> > > Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> > > 20/04/2007 18:43
> > >
> > >
> > >
> > >
> >
> >
> >
> > ----------------------------------------------------------
> >
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> > 20/04/2007 18:43
> >
> >
> >
> >
>
>
>
> ----------------------------------------------------------
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> 20/04/2007 18:43
>
>
>
>








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


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Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.7/771 - Release Date: 21/04/2007 11:56

Re: New BITX20A schematic posted on blog site

Arv Evans
 

Ron, Allison, and others...

The first schematic image on <bitx20a.livejournal.com> is stored as a
3954 X 2664 pixel .gif image. When you first access that page it shows
you a scaled down version that is 640 X 480. When you click on the
image it scales it up to the next larger size. When you click on the
image again it scales it up again. When you click on the image the
third time you get the full 3954 X 2664 pixel image that I stored on
that page.

At least that is the way it works on my Linux based Firefox browser. I
tried the same image with Mozilla, Epiphany, and Galeon browsers on
Linux and all work the same way.

If anyone is still having problems with viewing the schematic, I have
added a copy to the BITX20 Group's Files section. It is in the
"Hendricks QRP Kits BITX20A" folder.

Hope that helps.

Arv
_._

Ron McDowell - W5RCM / ZS1MCD wrote:


I got bit by this one...in Seamonkey, if you have it set to shrink
large images to fit the size of your window, it'll sometimes throw out
valuable info in the process. Firefox probably has a similar setting.
--
72, Ron - W5RCM / ZS1MCD
Austin TX / Hermanus ZA

On 23 Apr 2007 01:46:56 -0000, [Allison Parent <kb1gmx@...
<mailto:kb1gmx%40arrl.net>>] wrote:

Firefox here as well, Also tried Offbyone, and a tool I built with
Visual Pascal for viewing sites with virus or other malware, also
downloading the image and PSP and several of my other image viewers.

The problem was the files I got were shrunk to 640x480 and has no
resolution. Arv sent me a PDF that was fine.

Allison

___________________________________

Free Web Space for your Amateur Radio Hobby!
http://www.Ham-Stuff.NET <http://www.Ham-Stuff.NET>

Re: New BITX20A schematic posted on blog site

Ron McDowell - W5RCM / ZS1MCD <w5rcm@...>
 

I got bit by this one...in Seamonkey, if you have it set to shrink large images to fit the size of your window, it'll sometimes throw out valuable info in the process. Firefox probably has a similar setting.
--
72, Ron - W5RCM / ZS1MCD
Austin TX / Hermanus ZA

On 23 Apr 2007 01:46:56 -0000, [Allison Parent <kb1gmx@...>] wrote:

Firefox here as well, Also tried Offbyone, and a tool I built with
Visual Pascal for viewing sites with virus or other malware, also
downloading the image and PSP and several of my other image viewers.

The problem was the files I got were shrunk to 640x480 and has no
resolution. Arv sent me a PDF that was fine.

Allison


___________________________________

Free Web Space for your Amateur Radio Hobby!
http://www.Ham-Stuff.NET

Re: New BITX20A schematic posted on blog site

Allison Parent <kb1gmx@...>
 

--- In BITX20@..., Warren McRobie <w.d.mcrobie@...> wrote:

Allison Parent wrote:


--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
evans <arvid.evans@> wrote:
>
> A new schematic for the BITX20A kit layout has been posted (10
minutes
> ago) on the blog at:
>
> bitx20a.livejournal.com
>
>

Image is unviewable. I tried a few differnt ways and it's
apprently lost dome detail and missing lines.
Image is fine here, using firefox I save the picture as a gif, then for
printing I print a pdf (A3) to print at work.
Firefox here as well, Also tried Offbyone, and a tool I built with
Visual Pascal for viewing sites with virus or other malware, also
downloading the image and PSP and several of my other image viewers.

The problem was the files I got were shrunk to 640x480 and has no
resolution. Arv sent me a PDF that was fine.

Allison



73

Warren

Re: any kit updates?

Ronald Scifleet <ronaldscifleet@...>
 

Hi John,
The WA2EBY PA amp looks great and I would be grateful if you would e-mail part 2 of the article. My details are as follows:
Ron.Scifleet@...
Thanks,
Ron, VK2YQJ

----- Original Message ----
From: John YAHOO <v321uk@...>
To: BITX20@...
Sent: Wednesday, 18 April, 2007 5:05:10 PM
Subject: Re: [BITX20] Re: any kit updates?

From: "arv evans" <arvid.evans@ gmail.com>
To: <BITX20@yahoogroups. com>

It seems that one component to pushing IRF510s up to 14 MHz was to lower
the output impedance (improved stability and more power out with a 12
volt supply). We did change the design to use push-pull IRF510's. This
lowered even order harmonics and allowed lowering of the idling current,
but with two devices idling we did not gain that much in overall current
reduction.

I would be guessing if I said that IRF510s might work well at 18 MHz,
but I'm going to try that very thing in the near future. I will post my
results here for the BITX20 group.
<snip>

Here's a link to an article by WA2EBY using push-pull IRF510's to 28MHz
http://www.geocitie s.com/indrasep/ irf510.pdf There is a part 2 which is an
additional 4 pages showing power output graphs 1.8 to 30 MHzx with
different supply voltages 28V / 24V 13.8V. I cant find part 2 on the web
but I have it if anyone needs a copy emailed.

Here's another one using IRF510 to 30 MHz

http://www.hfprojec ts.com/projects/ hfpacker/ HFPackerAmp. pdf

John G3UGY




Send instant messages to your online friends http://au.messenger.yahoo.com

Re: Another mod for the kit

Arv Evans
 

Farhan

We received your email and are looking at the situation to see how
serious it is, and what needs to be done about it.

Thanks,

Arv
_._


ashhar_farhan wrote:


guys,

i am not sure how my previous post went missing. it is in my sent box
but it hasn't shown on the list. anyway, i hope i am not too late for
the final version. here it goes...

the vfo's fine tuning is with a reverse biased rectifier diode that is
acting as a varactor. the voltage on across the diode swings across t
the bias (as set by the fine tune control) for this diode. for
instance, if the voltage set on the diode is 5 volts and the vfo
voltage is 10 volts peak to peak, then the diode voltage across the
diode swings from 0 to 10 volts. which is fine.

the problem will happen when the bias is set to, lets say 2 volts. in
this case, the bias on the diode will swing from -3 to 7 volts. and at
-3v (remember this is a reverse biased diode), the diode will start
conducting and introduce noise vfo. this will falsely show up as
increased band noise when the fine tune control is set to the far end
of its range. an unsuspecting builder (like me) would imagine that
there is a greater atmospheric noise at one end of the band. but the
consequences of this are drastic: higher vfo noise, less sensitive
receiver, lower dynamic range and more spurious outputs.

the cure is pretty simple. restrict the range of voltages across the
tuning diode to a more positive range (lets say between 5 and 9 volts)
rather than 0 and 9 volts. the modification is simple: just insert a
10k resistor between the ground end of the 10k tuning pot and the
group. this will keep the diode permanently reverse biased.

as two added benefits this modfication results in a more linear fine
tuning range as well as a slower tuning range.

i am sorry for a late submission but i think it is crucial.

- farhan

Re: any kit updates?

Rahul Srivastava
 

Hi! Paul,

Ver3 schematics differ from present Ver !.1 sch on blog. Ver3 is thge 3rd variant that I constructed with some mods if you are interested in that one kindly follow the schematics for ver3 under files.

Ver1.1 is the work on going for kit so it is advisable to refer to blog schematics for the same it is much improvement.

73,
Rahul VU3WJM





Paul Tomlinson <m0eme432@...> wrote:
help me please, I'm confused. In my version 3 pcb layout that I have build my Bitx20 from, there are only 15 transistors, so where does Q26 come from?

----- Original Message -----
From: Warren McRobie
To: BITX20@...
Sent: Saturday, April 21, 2007 1:09 AM
Subject: Re: [BITX20] Re: any kit updates?

Looking over the latest circuit, looks really good.

One thing puzzles me tho - Q 26 should be on during receive not transmit
- or am I missing something?

Doug, Arv and the other proto builders are doing Amateur Radio a great
service.

Cannot wait for the kit to be ready.

Warren
ZL3LC

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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date: 20/04/2007 18:43








---------------------------------
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Another mod for the kit

ashhar_farhan <farhan@...>
 

guys,

i am not sure how my previous post went missing. it is in my sent box
but it hasn't shown on the list. anyway, i hope i am not too late for
the final version. here it goes...

the vfo's fine tuning is with a reverse biased rectifier diode that is
acting as a varactor. the voltage on across the diode swings across t
the bias (as set by the fine tune control) for this diode. for
instance, if the voltage set on the diode is 5 volts and the vfo
voltage is 10 volts peak to peak, then the diode voltage across the
diode swings from 0 to 10 volts. which is fine.

the problem will happen when the bias is set to, lets say 2 volts. in
this case, the bias on the diode will swing from -3 to 7 volts. and at
-3v (remember this is a reverse biased diode), the diode will start
conducting and introduce noise vfo. this will falsely show up as
increased band noise when the fine tune control is set to the far end
of its range. an unsuspecting builder (like me) would imagine that
there is a greater atmospheric noise at one end of the band. but the
consequences of this are drastic: higher vfo noise, less sensitive
receiver, lower dynamic range and more spurious outputs.

the cure is pretty simple. restrict the range of voltages across the
tuning diode to a more positive range (lets say between 5 and 9 volts)
rather than 0 and 9 volts. the modification is simple: just insert a
10k resistor between the ground end of the 10k tuning pot and the
group. this will keep the diode permanently reverse biased.

as two added benefits this modfication results in a more linear fine
tuning range as well as a slower tuning range.

i am sorry for a late submission but i think it is crucial.

- farhan

Re: New BITX20A schematic posted on blog site

Greg W:-) <onegammyleg@...>
 

I also tried the standard gif and that displays just fine.

gregW:-) OH2FFY


http://www.swdxer.co.nr/
======================================================================
SNIP
Image is fine here, using firefox I save the picture as a gif, then for
printing I print a pdf (A3) to print at work.
SNIP

Re: any kit updates?

Arv Evans
 

Paul

The beauty of modular construction like yours is that you can easily fix
things that don't work properly. I would think that you have adequate
shielding, but the real proof is in building and smoke testing it.

If you have access to a spectrum analyzer it would be interesting to
look for audio harmonics coming out of the balanced modulator on
transmit mode. Leonard KC0OWX first noticed these and as a result we
slightly modified the mike amp to clean things up a bit in that area.

In order to get clean RF output you need a clean VFO signal (minimal
harmonic content). Jim K8IQY changed things around a bit in the VFO to
improve signal quality. You may have noticed a series resonant 14 MHz
filter in the input to Q4 (new BITX20A schematic). This is primarily to
block VFO and unwanted mixer products from getting into the transmit stream.

Which H&P Stabilizer design did you use? It would be interesting to see
how many BITX builders are using some variation of the H&P design
(Klaas' original design, variations on Klaas' design, G0UOPL's 2-chip
version, FAST H&P version, etc.). It is really nice to have that +/-
1Hz stability if you are going to run PSK or something like that with
your BITX rig.

http://www.hanssummers.com/radio/huffpuff/index.htm

http://groups.yahoo.com/group/HuffPuffVFO/

Arv
_._



Paul Tomlinson wrote:


Thanks Arv, I was going to do that anyway. I've got a different VFO
design and a Huff-Puff stabiliser working nicely in a diecast box. The
PA is in another diecast box, and so I was going to fit what's left on
a small PCB. I was also going to fit 25mm walls around all the various
sections, and probably put the CO in a small metal box also. Do you
think this is enough?
Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
Sent: Saturday, April 21, 2007 9:45 PM
Subject: Re: [BITX20] Re: any kit updates?

Paul

You can use close spacing in a non-PCB layout if you put in shielding
between stages. The VFO and RF PA sections need their own shielded
enclosures. The problem we ran into with a compact PCB layout is that
it is quite hard to do such shielding without resorting to custom
fabricated shielding plates that would mount on the PCB. The expense of
doing this sort of defeats the idea of keeping the kit cost to a minimum.

Arv
_._

Paul Tomlinson wrote:

Thankyou for the reply, I'm glad you sent it to be honest. I've got a
working version on my bench now, but wanted to miniaturise it to fit a
nice old CB radio box I've kept for such a project. But now you speak
of instability problems caused by close spacing. So I better stop the
layout I'm doing and wait to see yours.
Thanks Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>
Sent: Saturday, April 21, 2007 7:48 PM
Subject: Re: [BITX20] Re: any kit updates?

Paul

Sorry about that. The Q-26 part exists in a new PCB based kit layout
for the BITX20.

We (Dan N7VE, Jim K8IQY, Doug KI6DS, and myself) are working on a new
kit layout for the BITX20A. While that kit is not yet available, some
members of the BITX20 group have been participating in discussions and
commenting on our design re-work effort. This is where the strange
component designations are coming from.

Making a parts and PCB kit available for the BITX20 eliminates some of
the parts restrictions that Farhan faced with his initial BITX design.
Designing a very compact PCB layout for the BITX20A required some
circuit re-design to avoid instability caused by close spaced
components. Keeping the kit cost as low as possible causes a new set
of parts restrictions and required some changes to allow utilization of
easily purchased and low cost components. Since the kit will be
marketed in the United States, it must be rigorously tested and must
comply with our FCC (Federal Communications Commission) rules for
spectral purity and stability.

All of these situations have caused us to build and evaluate two
prototype layouts. We are just now starting on the third prototype
build. Hopefully this will be the final prototype evaluation and will
result in a production run for the actual kit.

Schematics and other information for our kit building effort may be
found at the following web blog addresses (scroll back in time on the
first blog in order to find the schematics for Version 1.1 and version
1.0):

http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>
<http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>>

http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>
<http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>>

The Q-26 that you questioned shows up as part of the T/R switching
arrangement in the last blog. This set of blogs show the evolution that
we have gone through to arrive at a workable and compact PCB & parts kit
for the BITX20A design. I have used the BITX20A designation to indicate
that the kit design is a bit different from Farhan's original layout,
but that it still follows the technical intent of his original design.

I hope that clears up the confusion about apparently non-existing parts.

Arv - K7HKL
_._

Paul Tomlinson wrote:

help me please, I'm confused. In my version 3 pcb layout that I have
build my Bitx20 from, there are only 15 transistors, so where does Q26
come from?

----- Original Message -----
From: Warren McRobie
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>
Sent: Saturday, April 21, 2007 1:09 AM
Subject: Re: [BITX20] Re: any kit updates?

Looking over the latest circuit, looks really good.

One thing puzzles me tho - Q 26 should be on during receive not
transmit
- or am I missing something?

Doug, Arv and the other proto builders are doing Amateur Radio a great
service.

Cannot wait for the kit to be ready.

Warren
ZL3LC

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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
20/04/2007 18:43





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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
20/04/2007 18:43





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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
20/04/2007 18:43



Re: any kit updates?

Paul Tomlinson <m0eme432@...>
 

Thanks Arv, I was going to do that anyway. I've got a different VFO design and a Huff-Puff stabiliser working nicely in a diecast box. The PA is in another diecast box, and so I was going to fit what's left on a small PCB. I was also going to fit 25mm walls around all the various sections, and probably put the CO in a small metal box also. Do you think this is enough?
Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@...
Sent: Saturday, April 21, 2007 9:45 PM
Subject: Re: [BITX20] Re: any kit updates?


Paul

You can use close spacing in a non-PCB layout if you put in shielding
between stages. The VFO and RF PA sections need their own shielded
enclosures. The problem we ran into with a compact PCB layout is that
it is quite hard to do such shielding without resorting to custom
fabricated shielding plates that would mount on the PCB. The expense of
doing this sort of defeats the idea of keeping the kit cost to a minimum.

Arv
_._

Paul Tomlinson wrote:
>
> Thankyou for the reply, I'm glad you sent it to be honest. I've got a
> working version on my bench now, but wanted to miniaturise it to fit a
> nice old CB radio box I've kept for such a project. But now you speak
> of instability problems caused by close spacing. So I better stop the
> layout I'm doing and wait to see yours.
> Thanks Paul M0EME
>
> ----- Original Message -----
> From: arv evans
> To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> Sent: Saturday, April 21, 2007 7:48 PM
> Subject: Re: [BITX20] Re: any kit updates?
>
> Paul
>
> Sorry about that. The Q-26 part exists in a new PCB based kit layout
> for the BITX20.
>
> We (Dan N7VE, Jim K8IQY, Doug KI6DS, and myself) are working on a new
> kit layout for the BITX20A. While that kit is not yet available, some
> members of the BITX20 group have been participating in discussions and
> commenting on our design re-work effort. This is where the strange
> component designations are coming from.
>
> Making a parts and PCB kit available for the BITX20 eliminates some of
> the parts restrictions that Farhan faced with his initial BITX design.
> Designing a very compact PCB layout for the BITX20A required some
> circuit re-design to avoid instability caused by close spaced
> components. Keeping the kit cost as low as possible causes a new set
> of parts restrictions and required some changes to allow utilization of
> easily purchased and low cost components. Since the kit will be
> marketed in the United States, it must be rigorously tested and must
> comply with our FCC (Federal Communications Commission) rules for
> spectral purity and stability.
>
> All of these situations have caused us to build and evaluate two
> prototype layouts. We are just now starting on the third prototype
> build. Hopefully this will be the final prototype evaluation and will
> result in a production run for the actual kit.
>
> Schematics and other information for our kit building effort may be
> found at the following web blog addresses (scroll back in time on the
> first blog in order to find the schematics for Version 1.1 and version
> 1.0):
>
> http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>
>
> http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>
>
> The Q-26 that you questioned shows up as part of the T/R switching
> arrangement in the last blog. This set of blogs show the evolution that
> we have gone through to arrive at a workable and compact PCB & parts kit
> for the BITX20A design. I have used the BITX20A designation to indicate
> that the kit design is a bit different from Farhan's original layout,
> but that it still follows the technical intent of his original design.
>
> I hope that clears up the confusion about apparently non-existing parts.
>
> Arv - K7HKL
> _._
>
> Paul Tomlinson wrote:
> >
> > help me please, I'm confused. In my version 3 pcb layout that I have
> > build my Bitx20 from, there are only 15 transistors, so where does Q26
> > come from?
> >
> > ----- Original Message -----
> > From: Warren McRobie
> > To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> <mailto:BITX20%40yahoogroups.com>
> > Sent: Saturday, April 21, 2007 1:09 AM
> > Subject: Re: [BITX20] Re: any kit updates?
> >
> > Looking over the latest circuit, looks really good.
> >
> > One thing puzzles me tho - Q 26 should be on during receive not transmit
> > - or am I missing something?
> >
> > Doug, Arv and the other proto builders are doing Amateur Radio a great
> > service.
> >
> > Cannot wait for the kit to be ready.
> >
> > Warren
> > ZL3LC
> >
> > ----------------------------------------------------------
> >
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> > 20/04/2007 18:43
> >
> >
> >
> >
>
>
>
> ----------------------------------------------------------
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> 20/04/2007 18:43
>
>
>
>








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


No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date: 20/04/2007 18:43

Re: New BITX20A schematic posted on blog site

Warren McRobie
 

Allison Parent wrote:
--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv evans <arvid.evans@...> wrote:
>
> A new schematic for the BITX20A kit layout has been posted (10 minutes
> ago) on the blog at:
>
> bitx20a.livejournal.com
>
>
Image is unviewable. I tried a few differnt ways and it's
apprently lost dome detail and missing lines.
Image is fine here, using firefox I save the picture as a gif, then for printing I print a pdf (A3) to print at work.


73

Warren

Re: New BITX20A schematic posted on blog site

Arv Evans
 

Allison

I just now added schematic copies in jpeg, png, and Compuserv-gif
formats. This may make the blog a little slow to load if you are on a
slow Internet access link. If too slow, please let me know and I will
try a different tactic.

Arv
_._


Allison Parent wrote:


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

A new schematic for the BITX20A kit layout has been posted (10 minutes
ago) on the blog at:

bitx20a.livejournal.com

Image is unviewable. I tried a few differnt ways and it's
apprently lost dome detail and missing lines.

Allison

If anyone sees apparent problems with this layout, please let us know.
The more eyes we have looking at this the less chance we have of having
to rework it yet again. Hopefully this will be the final layout for
the
new kit version.

Thanks,

Arv - K7HKL
_._

Re: any kit updates?

Arv Evans
 

Paul

You can use close spacing in a non-PCB layout if you put in shielding
between stages. The VFO and RF PA sections need their own shielded
enclosures. The problem we ran into with a compact PCB layout is that
it is quite hard to do such shielding without resorting to custom
fabricated shielding plates that would mount on the PCB. The expense of
doing this sort of defeats the idea of keeping the kit cost to a minimum.

Arv
_._


Paul Tomlinson wrote:


Thankyou for the reply, I'm glad you sent it to be honest. I've got a
working version on my bench now, but wanted to miniaturise it to fit a
nice old CB radio box I've kept for such a project. But now you speak
of instability problems caused by close spacing. So I better stop the
layout I'm doing and wait to see yours.
Thanks Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
Sent: Saturday, April 21, 2007 7:48 PM
Subject: Re: [BITX20] Re: any kit updates?

Paul

Sorry about that. The Q-26 part exists in a new PCB based kit layout
for the BITX20.

We (Dan N7VE, Jim K8IQY, Doug KI6DS, and myself) are working on a new
kit layout for the BITX20A. While that kit is not yet available, some
members of the BITX20 group have been participating in discussions and
commenting on our design re-work effort. This is where the strange
component designations are coming from.

Making a parts and PCB kit available for the BITX20 eliminates some of
the parts restrictions that Farhan faced with his initial BITX design.
Designing a very compact PCB layout for the BITX20A required some
circuit re-design to avoid instability caused by close spaced
components. Keeping the kit cost as low as possible causes a new set
of parts restrictions and required some changes to allow utilization of
easily purchased and low cost components. Since the kit will be
marketed in the United States, it must be rigorously tested and must
comply with our FCC (Federal Communications Commission) rules for
spectral purity and stability.

All of these situations have caused us to build and evaluate two
prototype layouts. We are just now starting on the third prototype
build. Hopefully this will be the final prototype evaluation and will
result in a production run for the actual kit.

Schematics and other information for our kit building effort may be
found at the following web blog addresses (scroll back in time on the
first blog in order to find the schematics for Version 1.1 and version
1.0):

http://arvevans.livejournal.com/ <http://arvevans.livejournal.com/>

http://bitx20a.livejournal.com/ <http://bitx20a.livejournal.com/>

The Q-26 that you questioned shows up as part of the T/R switching
arrangement in the last blog. This set of blogs show the evolution that
we have gone through to arrive at a workable and compact PCB & parts kit
for the BITX20A design. I have used the BITX20A designation to indicate
that the kit design is a bit different from Farhan's original layout,
but that it still follows the technical intent of his original design.

I hope that clears up the confusion about apparently non-existing parts.

Arv - K7HKL
_._

Paul Tomlinson wrote:

help me please, I'm confused. In my version 3 pcb layout that I have
build my Bitx20 from, there are only 15 transistors, so where does Q26
come from?

----- Original Message -----
From: Warren McRobie
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
<mailto:BITX20%40yahoogroups.com>
Sent: Saturday, April 21, 2007 1:09 AM
Subject: Re: [BITX20] Re: any kit updates?

Looking over the latest circuit, looks really good.

One thing puzzles me tho - Q 26 should be on during receive not transmit
- or am I missing something?

Doug, Arv and the other proto builders are doing Amateur Radio a great
service.

Cannot wait for the kit to be ready.

Warren
ZL3LC

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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
20/04/2007 18:43





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

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
20/04/2007 18:43



Re: New BITX20A schematic posted on blog site

Allison Parent <kb1gmx@...>
 

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

A new schematic for the BITX20A kit layout has been posted (10 minutes
ago) on the blog at:

bitx20a.livejournal.com

Image is unviewable. I tried a few differnt ways and it's
apprently lost dome detail and missing lines.

Allison



If anyone sees apparent problems with this layout, please let us know.
The more eyes we have looking at this the less chance we have of having
to rework it yet again. Hopefully this will be the final layout for
the
new kit version.

Thanks,

Arv - K7HKL
_._

Re: any kit updates?

Paul Tomlinson <m0eme432@...>
 

Thankyou for the reply, I'm glad you sent it to be honest. I've got a working version on my bench now, but wanted to miniaturise it to fit a nice old CB radio box I've kept for such a project. But now you speak of instability problems caused by close spacing. So I better stop the layout I'm doing and wait to see yours.
Thanks Paul M0EME

----- Original Message -----
From: arv evans
To: BITX20@...
Sent: Saturday, April 21, 2007 7:48 PM
Subject: Re: [BITX20] Re: any kit updates?


Paul

Sorry about that. The Q-26 part exists in a new PCB based kit layout
for the BITX20.

We (Dan N7VE, Jim K8IQY, Doug KI6DS, and myself) are working on a new
kit layout for the BITX20A. While that kit is not yet available, some
members of the BITX20 group have been participating in discussions and
commenting on our design re-work effort. This is where the strange
component designations are coming from.

Making a parts and PCB kit available for the BITX20 eliminates some of
the parts restrictions that Farhan faced with his initial BITX design.
Designing a very compact PCB layout for the BITX20A required some
circuit re-design to avoid instability caused by close spaced
components. Keeping the kit cost as low as possible causes a new set
of parts restrictions and required some changes to allow utilization of
easily purchased and low cost components. Since the kit will be
marketed in the United States, it must be rigorously tested and must
comply with our FCC (Federal Communications Commission) rules for
spectral purity and stability.

All of these situations have caused us to build and evaluate two
prototype layouts. We are just now starting on the third prototype
build. Hopefully this will be the final prototype evaluation and will
result in a production run for the actual kit.

Schematics and other information for our kit building effort may be
found at the following web blog addresses (scroll back in time on the
first blog in order to find the schematics for Version 1.1 and version 1.0):

http://arvevans.livejournal.com/

http://bitx20a.livejournal.com/

The Q-26 that you questioned shows up as part of the T/R switching
arrangement in the last blog. This set of blogs show the evolution that
we have gone through to arrive at a workable and compact PCB & parts kit
for the BITX20A design. I have used the BITX20A designation to indicate
that the kit design is a bit different from Farhan's original layout,
but that it still follows the technical intent of his original design.

I hope that clears up the confusion about apparently non-existing parts.

Arv - K7HKL
_._

Paul Tomlinson wrote:
>
> help me please, I'm confused. In my version 3 pcb layout that I have
> build my Bitx20 from, there are only 15 transistors, so where does Q26
> come from?
>
> ----- Original Message -----
> From: Warren McRobie
> To: BITX20@... <mailto:BITX20%40yahoogroups.com>
> Sent: Saturday, April 21, 2007 1:09 AM
> Subject: Re: [BITX20] Re: any kit updates?
>
> Looking over the latest circuit, looks really good.
>
> One thing puzzles me tho - Q 26 should be on during receive not transmit
> - or am I missing something?
>
> Doug, Arv and the other proto builders are doing Amateur Radio a great
> service.
>
> Cannot wait for the kit to be ready.
>
> Warren
> ZL3LC
>
> ----------------------------------------------------------
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date:
> 20/04/2007 18:43
>
>
>
>








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


No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.446 / Virus Database: 269.5.6/770 - Release Date: 20/04/2007 18:43