Homemade 45rpm disc recording

Handmade disc recording made on a coffee tin plastic lid

Whilst clearing out a cupboard the other day I chanced upon a piece of my history in the form of a small 45rpm disc recording that an old school friend and I made in 1969. Using an old record turntable with a very large horn as the acoustic microphone we recorded me saying some words and poems onto the polypropylene lid of an old coffee jar. Shouting VERY loudly, the sound is imprinted onto the disc in just the same way old gramophone records were made back in the 1800s. The metal foil inner lids of cocoa tins were also quite good for this as I recall. Francis Wood, my school friend went the whole hog and put the record into a homemade sleeve (with suitable handwritten text) with inner cover and the disc finally inside. I did play this disc some years ago and it was still intelligible (just) but nowadays I have no 45/78rpm kit to play it on. I remember the first time we made such a disc back in 1962 how amazed I was that it worked.

A Homebrewer's Lab

VU2ESE's workbench - not unlike mine!

Ashhar Farhan VU2ESE has an interesting page setting out what basic equipment he considers a QRP homebrewer needs. See http://www.phonestack.com/farhan/lab.html. The only additional piece of equipment that I have found really useful is a small box to measure inductors and capacitors. The LC Meter kit produced by the Cambridge and District Radio Club has proved invaluable. A small spectrum analyser would also be useful, but these do not come cheap, although there are designs on the internet to make simple ones.

Micro80 4-transistor transceiver QSO

After some time without use, I resurrected the little Micro80 4 transistor transceiver for 80m last weekend. To increase the power a bit I've now got provision to run it from an external gell cell battery at 12v, so giving me about 2dB more RF out compared with the 9V internal pack. Using it with the bench PSU was impossible because of 50Hz hum pick-up. I also managed to improve the AM breakthrough by around 10dB at least by putting a 4n7 cap across the base-emitter junction of the first stage of the darlington in the RX AF. This makes it a usable radio on 80m at night now as it is not obliterated by the BC stations around 4MHz. Success soon followed with a solid QSO with G3XIZ in Biggleswade around 30 miles away late Sunday afternoon.