David Macnaughton and his Fascinating World of Amateur Radio

MY NEW PROJECTS & ODD THINGS

CONTENTS

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THE 40 METRE VALVE TRANSCEIVER - THE BA100 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 photos.  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 Caustic Soda 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  SINGLE 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 - MJE10012 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 - stay tuned         HELP PLEASE... 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 nothing available. Someone, somewhere???     AN INTERESTING ENGINEERING ISSUE 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 problems?

 

LATE 2007 - THE BENDIX TA12C A recent bout of shingles left me looking for a project that would take my mind of my poor condition. I selected my WW2 Bendix TA12C which I have been wanting to put on air for some years. I needed to make a 50W modulator, a power supply and some control circuitry and a cabinet to house these new units in. Well, I finished the project. The TA12C is now on air with 30W output and getting good reports. By the way, my shingles still continues after nearly 7 months! (as at 2nd Feb 2008) The TA12C TA12C internals VK2BA and the TA12C TA12C Modulator - 2 x 807's TA12C equipment cabinet with the modulator fitted - the P/S is to go on the bottom and the top unit is control circuitry. It also needs a coat of paint. The old rig is now on air running about 30W o/p.

 

My PYE MTR1 I recently aquired this lovely PYE MTRI MK2 and matching receiver. This has been restored to the point where it has been on 40M and has made one on air QSO. Well, it does work! It is now in my museum.