Twelve attendees were privileged to see the substantial amount of “home brew” projects that turned up at Branch05 on the night of Wednesday 27th February 2019.
Arthur’s project (ZL3JQ) was created by him some 33 years ago. A double sideband transceiver it puts out about 3 watts max PEP and can do Morse or Voice. It can run for hours on a small 12 volt motorcycle battery as it draws barely a third of an amp on TX and almost nothing on RX.
Bruce’s project (ZL3TFM) dates from just prior to the Canterbury Earthquakes. It came as a kitset from Milton Keynes Amateur Radio Club in the UK, and cost about NZ$80, landed here. It puts out about 5 watts on LSB in the 80 metre band. I believe there was some initial instability but someone at the club helped with a minor modification that sorted it.
John (ZL3IB) had his home made Antenna Tuning Unit there. The case was salvaged, indeed almost all the parts were as John willingly admits he wants to “beat the bank” when it comes to paying out for new components. The 2 meters were salvaged from old stereo units Vu meters and re-jigged to suit, one being a power in Watts indicator and the other being for SWR. The guts to run the SWR meter was isolated in a small aluminum box, mounted inside the main casing (that being a small circuit-board that he’d made up).
He explained that Aluminum was a far better choice as steel cases affect the components inside with their magnetic properties. The Antenna Tuning Unit was based on a design from Break-In magazine of June 1983. John explained it was important that the two internal coils be at right angles to each other and as far separated as possible, so as to minimise interference. The ATU worked the entire range, one aspect of its components handling the 10 metres to 20 m range and the other circuitry covering the remaining 40 metres through to 80 m bands.
The “other” Bruce (ZL3TDF) showed a home brew Field Strength Meter, intended more as a “go/no go” indicator than as a measuring device. One system he had was to be mounted near his antenna, so he can at a glance get an indication on the meter, if he’s successfully transmitting.
His other unit was for handheld use.
Gilbert (ZL3GIL) had a Morse Keyer generator that ran off 4.5 volts of AA batteries. Including auto power-off as part of the circuitry. He also displayed a 1 watt Transceiver for the 6 metre band. It’s not quite finished yet and therefore untested so far. Gilbert said something he got as a kitset from “hamshop.cz” but I cannot be sure which of his two items that was.
Graeme (ZL3NK) brought in his adjustable screwdriver antenna intended for car mounting. He indicated a number of the design features but did explain that some components had to be custom made on a lathe. A discussion with those present then evolved about the threaded sections needed in such antennas and whether some form of threaded plastic might be superior.
Thanks to all the club members who brought in their projects to show us. It was a great night and hopefully even more club members will be able to make it to the next one.
Author Catherine ZL3CATH
