Hi fellow builders,
posting this link for information

- its a digital frequency readout using a PIC micro with user
definable IF offset - might be of use to the group, and I readily
admit its outside Ashan's original inexpensive transceiver concept -
it would probably cost more to build than the BITx20 itself!
Still, I think its an elegant solution, so let me know what you think.
Its .PDF, approx 162K in size
73 de VK3BFA Andrew

Hans Summers wrote :

...in which G0UPL travels to his local hardware store to further investigate
the nature of the infamous tap washers, and in particular the differences
between ordinary and "delta" washers.
Both are know as 1/2 inch tap washers but both measure more than 1/2 inch
(12.7mm). As close as I can measure with my ruler:

As I understand it, the " half -inch' refers to the bore of the water
pipe with which they are associated - and includes three-quarter and
one-inch as part of the series.

A typical "half-inch" tap washer in the past would measure perhaps
three-quarters of an inch dia., but in more recent times the
proliferation of fancy bathroom ware has given rise to a variety of
custom taps (faucets) with their own washers.

My own houshold taps ( I'm told ) have ceramic washers which ( I'm
told ) never wear out and ( I know ) are drip-free.

Regards, Sam C.
ZL1TOI

Hi Charles,
what you describe has been used in VK for a while now, described (and
used) by Drew Diamond VK3XU - he is a master of this style of
homebrewing and has published many articles over the years (and 2
books) - some construction articles are available in .PDF format from
the website
go to AR mag page and have a look around.
Well worth the effort for inspiration!
73 de VK3BFA Andrew

-- In BITX20@..., "Charles" <charles@d...> wrote:

Hi

I was wondering how to make a pad for the chip then thought use a
piece of PCB with a cut through the copper in the centre and then
additional cross cuts of the copper to make the lands for the

holder.

By bending out the legs of the holder they can be soldered to the

pad.

Chip Pad Photo added to my album.

Charles G4VSZ

开云体育

BITXers

Since the tap washers, faucet washers here in the US, are mylon or
similar plastic type material, it would seem that they do not
contribute much to the functionality, other that to hold the wire
coils in a circular shape. Also, since there is no magnetic field
contribution by the nylon or plastic dore former it would seem that
one could cut a small slot in the material to facilitate winding the
coil without having to thread each turn through the center hole.

After the coil was wound one could use hot-melt glue (or anything
sticky that hardens well) to close the slot and to mount the coil to
the chassis material.

Has anybody tried this yet?

Thanks,

Arv-K7HKL
_._

Hi

I was wondering how to make a pad for the chip then thought use a
piece of PCB with a cut through the copper in the centre and then
additional cross cuts of the copper to make the lands for the holder.

By bending out the legs of the holder they can be soldered to the pad.

Chip Pad Photo added to my album.

Charles G4VSZ

开云体育

Hello, I have uploaded a photo of a two-hole "binocular" ferrite
core (see G4DFV album). Ashtar, please can you tell me if this is
anything like the TV balun that you have used?
My core measures 13mm x 7mm x 6mm, the holes are 3mm diameter and
the centres are spaced 6mm.

Duncan G4DFV

Farhan

Sorry to hear of your problems. I'm sure you are right to fight for the free
exchange of information.

One possible solution is to use an anonymisation service such as
. In this case the URL to the BITX20 group
would become
.

I work for a US company. One might expect freedom of information to be
assured. But they insist nevertheless on blocking any website which meets
some criteria of being pornographic, related to betting and gambling, or any
terrorist activity. I don't know if they thought that perhaps we would sit
here in the office in full view of our colleages watching porno movies or
something. Anyway be careful I'm getting on my soapbox here...

To cut a long story short, I had a big battle and I lost, they still refuse
to change it. The battle arrived when I tried to look at the website of
Thomas OZ2CPU, whose excellent web page I have visited
many times in the past. Only to find that it was blocked, with a message
something like "if you feel this web page has been wrongly blocked, please
contact the IT helpdesk". You can contact them as much as you like, and if
they don't feel it is related to your business requirement they won't
unblock it, even if it IS wrongly blocked. A colleague wanted to buy
something from a camping store. Couldn't access it. So had no option but to
take a long lunchbreak of 2 hours, on company time, to visit the store. Even
if it's non-business, it can assist business by making the employee's life
easier.

All of which led me to write my own internet browser application, which
enclosed an Internet Explorer component. On coming across the hated IT
helpdesk message, it redirects its enquiry to anonymization.net which
(nearly always) gets the page Ok. This is all done in an invisible way, the
actual real address at anonymization.net is hidden from the user. So I was
able to give the application to my friends in the company to assist them in
streamlining their non-business related activities, in the knowledge that if
the information finds its way back to the IT dept, at least it won't be
instantly evident how it works, though I don't doubt that they would be able
to trace it eventually, having access to everything.

Sorry to have got on my soapbox even though I tried to stay off it - this
issue touches a raw nerve. Good luck with battle which is much more serious
than my little problem here.

73 Hans G0UPL

--- In BITX20@..., "ik1zyw" <pcravero@a...> wrote:

It's me again.

Has anyone attempted to list all BITX20 components? I haven't found
any link on Ashan's page. Here is my attempt at listing all
components, except for the IRF510 PA (had no time).

I have uploaded in the Files section a TXT file with a component list
for BITX20. It DOES include driver/PA section but it DOES NOT include
inductors. The list is meant to be a list you give to the shop
attendant and then return home with everything you need to build a BITX20.

Tap washers can be purchased at a hardware store, which usually
doesn't sell electronic components. Coils wire can be salvaged from
old transformers.

Please someone cross-check my work!

73,
Paolo IK1ZYW

...in which G0UPL travels to his local hardware store to further investigate
the nature of the infamous tap washers, and in particular the differences
between ordinary and "delta" washers. Samples were successfully returned to
my office and analysed in the photocopier next to a ruler then via the
scanner ;-)

Attached is a picture. For the benefit of those who don't get emails but
read this on the Yahoo group website, I've put it in the G0UPL photos folder
too. Note: Ruler measurements to the left of the 6 inch mark are in 16'ths,
to the right are in 10'ths.

Both are know as 1/2 inch tap washers but both measure more than 1/2 inch
(12.7mm). As close as I can measure with my ruler:

"normal" "Delta"

Outside diameter: 23/32 (18mm) 19/32 (15mm)
Inside hole diam: 5/32 (4mm) 3/16 (5mm)
Thickness: 5/32 (4mm) 3/16 (5mm)
Price: ?0.45 per 3 ?0.45 per 2

72/3 de Hans G0UPL

for the last 48 hours, groups.yahoo.com has been blocked out by the two
major bandwidth providers to india. most of my internet accounts belong to
isps that in turn take their bandwidth from either of these two (i have
several).

this has been done as the indian govt. asked the isps to block certain a
fanatic group (read 'hate') from being accessed from india. some of us
are fighting this with the govt. and i hope that the access will be
restored soon.

until such a time, i cannot see the pictures that are being uploaded
although access the emails (the emails are to and from my server located
in boston). i cannot wait to see all the lovely efforts being made by
everybody and it feels like being left out of the party.

though a number of users have suggested using proxies to gain access to
the site, i want to regain my right to free exchange of ideas and
information as much as i believe the fringe hate group should. the issue
has become significant to a number of us in india.

- farhan

Hi

I have just posted a block diagram of the BITX - I hope I have
correctly identified all the section of the main schematic diagram.

Let me know of any errors.

This will be used as part of a teaching aid to Amateur Radio Students
in UK.


Charles

开云体育

Hi

I uploaded my BITX20 pictures into the photographs section


I also re-organised in there a little, so that the photos which were at the
top level are now sorted into directories by callsign.

Some notes on my version:

You will see the first picture has the BITX20 in the foreground and my
80/40m homebrew receiver
in the background. The
frequency counter of the receiver (also homebrew, see
) is hooked up to the
BITX20 VFO on 4.278.16MHz. You can see the same frequency reading on the
BITX20 readout, i.e. 14.2 from the dial + binary 64 + 8 + 4 + 2 + 0.5 =
14.278.5.

The other picture shows 14.175MHz. I fitted an on/off switch, tx/rx switch
and frequency counter on/off switch (in case the counter generates an
objectionable birdie or other noise). A greed LED indicates power is on, the
red LED indicates TX.

I included a photo of my simple 2-chip 8 LED binary readout frequency
counter that I installed in the BITX20 front panel. The details of this
counter can be found at .
It costs approx ?2.00 in parts.

I constructed my BITX20 as a series of 15 modules. The VFO is built directly
on the main chassis behind the tuning controls. The remaining modules are
each built "ugly" on a 2 x 1 inch piece of PCB stock, mounted at right
angles to the chassis. This method will allow me to experiment easily with
variations on the different modules. If necessary I could easily move all
the modules around because they are just soldered to the base board at
either end of their 2-inch length. This method also provides for some
"automatic" screening between each stage. All the modules except the product
detector/exciter are shown in the "modules" photo subfolder. Sorry for the
low resolution images of the modules. Some of the main pictures were taken
on a friend's camera. if you have an old unwanted digital camera which is
less old than my 640 x 480 resolution dinosaur, you know where to send it
;-)

The rig is now awaiting testing and debugging but due to family commitments
there may be some significant delay.

72/3 de Hans G0UPL

Hi All, Just to clarify, the Delta Washers I mentioned in the earlier
post are shaped more like a standard Torroid a little bigger than a T
50 and not as big as a T68 so I guess around a T55????? A standard
1/2 inch or basin tap washer in the uk is much bigger and the hole in
the centre is quite small. I did purchase some of these also to
compare, Catalogue no C54012 ?1.29 + VAT for 10 same Supplier. I use
a PIC LCD Capacitance and Inductance meter that I made last year to
give me the values of the coils, as yet I have not made them for the
BITX. As mentioned in another posting, the core for the winding can
be made out of various things, ball point pen plastic etc. When I
wind the coils I will give some uH values from my meter. All the best
and happy constructing, de Bill G0BAK.

Hi

After reding over today's posts...here are a couple of thoughts and
comments:

1) The manufacturer and model number for the faucet washer used in
BITX20 coils is probably much ado about a triviality. The requirement
for air-core (or nylon core, to be more correct) toroid coils in your
BITX20 is a reference to the shape and to the absence of ferrite
material in the magnetic field. I suspect that if you wanted you
could use 'slices' from the body of a plastic ball-point pen. I used
1/4 inch wide slices from a piece of 1/2 inch PVC pipe (a bit larger
than the faucet washers, but also required a few less turns). No, I
don't know what effect the different dielectric constant of the PVC
had on the result.

2) Many years ago I obtained some PCB material that is quite thin
and flexible. My method for making the "pads" is to punch them out of
this material with a conventional paper punch (the pliers shaped type
you can buy for a couple of USD in many local stores). I sometimes
punch out a handfull when I have a few free minutes (it makes a great
distraction during those boring commercials on US Television), or if
none are immediately available I will punch out just what I need as I
build a circuit.
At times I have made pads from thicker PCB material by just punching
them out from PCB scrap(and from used boards when parts have all been
removed) by using the larger lever-operated paper punch on my desk.
Also, in the US Harbor Freight sells a compound-action pliers type
punch (about $10 USD) complete with different sized dies, see
<www.harborfreight.com> and search for "punch".
FYI: My "pads" using the thin PCB material measure 1.4 PF between the
circuit connection and underlying PCB substrata. I'm using "Super
Glue" to stick them down.

3) Yes, when I am in a hurry, like assembling my first BITX20, I
resort to point-to-point self-supported wiring...the UGLY method. It
is quick and effective, but nearly impossible to repair if the
defective part is two or three layers deep in the rats-nest of
connections.

4) My initial BITX20 effort did not use the LM-386 AF amp. Instead
I just used a 741 Op-Amp and relied on headphones-only for the audio
output. I guess I neatly sidstepped the schematic error regarding the
wrong pin being indicated for the + voltage! ;-) Since then I have
added an NPN (2N3904) driving an NPN-PNP (2N3904 & 2N3906) pair for
1/2 watt of audio to the speaker.

Maybe I am different but I see Farhan's elegant design as very
interesting because it allows the builder to match up his particular
incantation of the rig with the contents of his junk box.

My BITX40 is coming along quite well. Several modules have been
assembled and tested with just the IF filter, VFO, and the linear amp
left to finish. I am waiting for an order to be delivered from "Dan's
Small Parts" before I can continue. My junk box became severly
depleted of the more commonly used parts!

73's
Arv
_._

开云体育

Hello Fello wBuilders,
think I stuffed up a previous message post - anyway, have posted a
photo of my humble efforts at kitchen sink PCB making for the BITX20
IF Amp - its in the VK3BFA folder. Any comments on probable mistakes
welcome - will try and load it with components tomorrow if I can
ignore customer jobs already on the work bench hi hi. I build on the
track side of the PCB (semi ugly/manhattan) - so much easier to
troubleshoot.....
73 de VK3BFA Andrew

On Jun 26, 2004, at 11:03 PM, MILAREPA wrote:

Dear forum,
The IRF510 and 2N2218 is not available here in INDONESIA,
?
-Could you suggest an alternative for 'linear amplifier module' ?
?
-Can I just use:
HF BANDS QRP LINEAR AMPLIFIER?- 4WATT or
TEN WATT LINEAR AMPLIFIER all by Harry Lythall - SM0VPO
Since 2SC.....( Japanese) transistors are available here.

Both those circuits will work fine, as will most any other QRP amp
circuit. A broadbanded circuit is easier to build and use because it
requires no tune-up and is less likely to have a parasitic oscillation.
Be aware that those two amps NEED a low-pass output filter. For 20M,
the BITX20 filter will be fine. For other frequencies, most popular
radio handbooks have equations and design examples for the frequency of
interest.

Readers are reminded that Harry SM0VPO likes to share his work, but
doesn't like seeing others pirate it or claim it as their own. So be
sure to provide attribution (as was done here) when you share his
stuff. He has the best homebrew radio site in the world, and we'd like
to encourage him to keep it online, by respecting his work and his
copyright.

Jim N6OTQ