Archive for May, 2016

Making Waves–Bakelite and Moving Coils….

I have been rather busy of late so haven’t had so much time to play with anything radio.  I did, however, manage to pop into the local antiques dealer (Notions) and take a look around.  Amazing what fascinating stuff you can find in these places.  What I did find (and purchase) was three moving coil meters (milliamperes and microamperes) in Bakelite cases.  One dates back to WW2 and was for military use and the other two are just post war.  All are made by English manufacturing companies (unfortunately no longer in existence) with the quality one would expect from this era.

IMG_20160512_154752 The three moving coil meters.

20160522_083809This is the one from WW2.  The K in the centre of the dial above an arrow denoted it as military.  The range is 0 – 150mA and yes, it does still work and is accurate to +-1%.


This one is of interest in that not only does it have a more visible dial and a manufacturer’s name – Crompton Parkinson Limited – it also has a completely clear cover enabling the workings to be seen.  The internal resistance of 5Ohms is clearly marked on the front so this can be included in calculations for power and current.  Admittedly, with a full scale deflection at 15mA you are not going to be testing any high power apparatus with this.

Researching Crompton Parkinson Ltd, I discovered that Crompton & Co. was a lamp manufacturer founded by R.E.B. Crompton in 1878 and F & A. Parkinson Ltd. was a successful electric motor manufacturing company.  They also purchased Vidor Batteries – a manufacturer of flashlight and radio batteries – and Burndept Wireless.  If you follow this link: Wireless World 1925 it will take you to a pdf copy of a page from Wireless World, September 30th 1925 describing some of the valves made by Burndept.


Making Waves–Key bashing and other escapades….

Well, yet again I have found myself pushed to make time to spend on the radio.  Looking back through the pages of my log book I see many QSOs using CW, the occasional JT65 and even more infrequent PSK31 or PSK 63 one.  J3E seems to be a tad rare (I count about 5 during this year so far.  I must admit, I do prefer to use the key these days and find that I can get my signal so much further with so much less effort and power.  Yes, I spent my money and bought the MD-200 desk mic from Yaesu to accompany my FT-DX1200 but it sees so little use. Aesthetically it does look nice though.

yaesu-md200_web1 The Yaesu MD-200A8X Desktop Microphone

Yesterday I was pleased to manage a QSO with JT1CO in Mongolia for a new DXCC country.  This was using 90W of CW into the MQ1 mini-beam on 15m (21MHz).  I also managed a couple of Russian contest stations on 15m yesterday.  I must say, it is good to hear some of the higher bands opening up again.  I tried 12m and 10m but the only openings on these appeared to be between stations near the equator and nothing was heard this far north.  the 50MHz (6m) band should be coming to life soon with the sp-e season but the SFI is still too low for it here and for the brief period that it is open most of us will be at work or otherwise engaged when the real DX is happening.

Earlier in April I managed to work many of the Yuri Gagarin special event stations on CW celebrating 55 years since his 1st space flight.  Following that I managed several of the HG225 stations for Samuel Morse.  I didn’t get all of them though so no award for that one.  I did receive my CQWW CW award for my entry into last year’s contest though which is now hanging proudly on the shack wall.  Maybe it is not the highest score in the world (#6 in the UK) but for 5W into a wire dipole I was pretty pleased with it for a first attempt. Single Op QRP Unassisted.

CQWW Award CQWW CW Contest.

I have also been busy designing my next project.  1st prototype boards have been etched – now I just need to cut them to size and drill them.  The latter will require a very small drill bit (0.6mm) and either a steady hand (ahem) or a drill stand.  I do have a drill stand so this will probably be the way.  I am attempting to build a transceiver in stages to cover the main amateur bands (40, 20, 15 and 10m).  The oscillators used are simple Colpitts form and the next stage is the buffer and keying circuit.  The boards are pictured below for the 2nd stage.  I shall then move on to final amplifier (to 5W) and band pass filters for each band.

20160426_145742 PCB’s created in the CVO Lab.

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