November Meeting HARC/CARC Challenge

This year’s HARC/CARC Challenge, held on 30th November and hosted by the Crawley Club, got back, as Adrian G4LRP said, to basics. Of the Horsham team Alister G3ZBU was the tech support who made the idea come to life and supplied the kits, and David G4FQR was the HARC constructor, ably assisted by Paul G4TMC. Robin G3OGP was the CW op. The Crawley Club fielded Derek G3GRO, Stewart G3YSX, Richard G4ANN and Biton Walstra (2E0WAO). The two judges were Adrian G4LRP from HARC, and John G3VLH from CARC.

Set by Horsham this year the task was for each team to build a single valve transmitter, a simple receiver, fabricate a Morse key fabricate from a broken CD (don’t ask!), connect a short wire antenna and send half a page of Morse. All required components, including four 1.5V pen cells and two 9.0 volt PP3 batteries, plus the circuit diagram, were supplied in bags by Horsham. Both receiver and transmitter would be built on small screw type tag strips so no soldering was required. The winning team would complete the building process and send the prepared CW with the fewest errors. Alister would act as guide/consultant for both teams. Adrian suggested that the transmitter would take 10 minutes, the receiver ten minutes and the CW transmission another ten minutes. Thirty minutes total? Ho, Hum!

The transmitter, a single valve crystal oscillator resonant on 80m used a cathode-keyed 6BA6 and comprised about a dozen components. An audio oscillator using a 555 timer chip on a piece of pre-assembled Vero board supplied the modulation. The receiver was a simple crystal set, the output of which was connected to the input of a small active Sony speaker. Each component was screw-connected to the tagstrip using a screwdriver, the only tool required for the building process.





As Adrian whispered to me half way through the construction phase, there was an element of the tortoise and the hare in the way each team approached their tasks. As the pen cell batteries had limited capacity but had to power the valve filaments, if you spent a lot of time fault finding with the power connected you could literally run out of steam before completing the CW transmission. Whereas, if you were slower but more methodical with the construction process, you could have power in hand to complete the transmission.

First to complete their construction was the Horsham team, then Robin G3OGP sent the half page of code which was received by Alister, and took around 15 minutes.

Crawley was struggling by this time, but after some dogged fault-finding detective work they also had their system up and running. Time for some CW from the home team! Derek G3GRO had been elected as CW op and Ted and Dick both did the receiving bit. The fact that HARC had by this time finished their transmitting session in fact worked out well as there was no QRM.



Again the CW transmit session took about fifteen minutes – and then it was time for the judges to come forward and have their say. The prepared CW was from about half a page of plain language text divided up into 5-letter groups. And this was the deciding factor. The Horsham text checked out by Adrian had been very accurately sent and copied. However, when John checked the Crawley club effort two vital lines were missing from the text.


So the Horsham Club regained the Interclub Cup, which was presented by CARC Chairman Stewart to HARC Chairman Adrian. It had been a truly well thought out project and provided an entertaining evening for all present, whether actively taking part or watching from the sidelines. Congratulations and well done, Horsham. See you next year!


John G3VLH