THE 40 METRE VALVE TRANSCEIVER -
I was recently asked ifthis
project was ever completed. The answer is not yet. The reason is that I
was very ill with encepholitus in 2006 and again in 2008. This
resulted in 5 weeks total in a coma and this resulted in serious hand
shake. The tightness of the construction and in particular the
difficulty I had soldering meant that I have put the project to bed for
a period. Try soldering when the solder is shaking and you have to chase
it with an iron that is probably shaking as well! This is a
project that I intend to complete and I should be able to do that before
too long. For those who have emailed me, thanks for the encouragement.
4th JUNE 2008:
To satisfy a number of
on-air requests for information about this project, here are a few early
The chassis is well advanced but not
complete. It needs further shields then it will be totally pulled apart
for a final cleanup and dipping in Caustic Soda. It is real fun putting
it back together again.
15th JUNE 2008
The metalwork kit after dipping in
A probable kit of bits for the
project - yes, a lot of collecting went on!
Now, to put them together
14th JULY 2008
Things are getting serious, folk.
Just think of the possibility that it may not work!
The project is taking shape. The
panel is a print-out from Photoshop and has a sheet of acrylic over the
top (see below). The blemishes are reflections from the cloth. A knob
still has to be found - I bought it. The top cover slides in - yes, a
possible cause for TVI. I have a rescue worked out in case of this.
6th AUGUST 2008
The wiring is being put in. Each
section is being made to operate when is completed. So far the following
sections are working: The audio output (6GW8), carrier oscillator and
balanced modulator (6AR8), 9MHz carrier amplifier (6BH6), VFO amplifier
(6BH6). I am having a few problems fitting in the microphone amplifier
but it will fit.
The inspiration for the BA100 has
been an article by John Isaacs W6PZV in the book
SIDEBAND FOR THE RADIO AMATEUR (ARRL 1970 - page 73)
I am going my own way in many areas,
even the valve line-up.
At the moment, this is likely to be:-
Receiver RF amp - 6BZ6
Speech amplifier - 12AT7
Receiver mixer - 6AK5
VFO amplifier - 6AK5
Balanced modulator - 6AR8
IF amplifiers - 6BA6
Product Detector - 6C4
Transmit mixer - 6BE6
Transmit Driver - 12BY7
RF Power O/P - QQEO6/40 (5894) type
Voltage Regulators - 0A2, 0B2
Transistor regulator -
VFO - Vackar Oscillator - MPF102 (osc)
+ amplifier 2x 2N2222
Filter to be used - 9MHz McCoy Silver Sentinal and matching crystals
After all, I have had two of them put
away since about 1968 - Now is a good time to give one of them a run
More on this project soon -
The BA100 panel
I tried to use Adobe Illustrator but
it was all too time consuming. I reverted back to Photoshop and put the
panel together over the top of a scan of the original aluminium sub
panel. It was an exercise in the use of layers. I used a resolution of
300dpi. The little scales did come from my many hours with Illustrator
but I am still not really happy with them. Somewhere between this
photoshop artwork and cutting out the clearance holes for the controls
that were mounted on the aluminium and the cutting of the clearance
holes in the acrylic over-panel I lost some registration. Oh well!
nothing a day of slotting and fiddling can't fix. The big advantage with
this type of panel is that if anything is subsequently modified, or
added etc, it only needs an upgrade to the Photoshop artwork and a new
panel can be created in minutes.
If anybody comes across a set of
scales as digital images similar to what I have used in this panel
please pass on the details to me. Even a printed sheet of them could be
used. What I think could be very useful would be .jpg images of
scales from about 1/2" (12mm) up to about 1 1/2" (30 or 40mm diameter),
but the thickness of the markings would need to be the same for all
scales ie perhaps 0.3mm. That is what is wrong with having just one high
resolution scale and making it larger - the markings become thicker if
the image is made larger.
Here is an example of what I am
talking about. One problem with this one is that there is no dead centre
indicated. Once one has an image like this one can change colours,
diameter, rotate the image 15 degrees (or whatever) and delete what is
not needed. So this image could become suitable for a two position
switch, a five position switch, a volume control, plate tuning etc etc.
At the moment I don't have the time
to devote to that project, and yes, I am aware that a CAD programme will
do it but for the number of times that I make panels it is not worth
while buying a suitable programme. Someone has probably already done it.
I spent much time searching the web for suitable images but found nothing. I find it hard to
believe that with many thousands of keen folk making gear, that there is
DRILLING HOLES IN ACRYLIC SHEETING
This is a sample strip of 2mm acrylic
sheet. The drill is a step drill and if you are into construction of
radio apparatus, you need one. I had never used one until Owen VK1OD put
me onto them. You can easily drill holes up to 25mm diameter (1") in
aluminium and surprise, acrylic sheet. Despite the look of the tool, I
have had no troubles with jamming, grabbing, melting etc. What other
tool would cut to 2mm from the edge of 2mm acrylic without major