All posts by Gareth Howell

Catching RF with a Roach Pole

 

One of our members, Victor G3JNB, is developing a new general purpose, multi-band vertical antenna to support his HF DXing operations.

On May 4th last, when his neighbour’s elm tree dropped two boughs, he lost his pulleys and halliards. He reports on his latest attempts to get the RF out there:

For a variety of reasons, I needed to move away from the 97ft doublet and the wire in the sky. Having had considerable DX success with helical verticals for 17 and 30m made from old fishing rods, I decided that this natural disaster was a good opportunity to experiment with a multi-band version using ground radials from an earlier aerial system, plus a major earth system.

The 30ft SOTA telescopic mast in another market place is surely just a splendid fisherman’s roach pole, complete with top eyelet. Modestly price when compared with commercial models, I acquired one and put on a 45ft helical winding over the upper 25ft. Removing the base cap from the rod, I slid the pole down onto a strong aluminium pole that was concreted into the ground. Said pole was recovered from a defunct washing line ‘whirligig’ and is remarkably substantial. No guy wires and just a brace to the hedge. Time will tell if gales permit it to stay up!

Currently, RF arrives at the feed point from the shack Drake ATU and Balun with some expected loss over the intervening 100ft.. However, this format loads on 20m and 40m like a dream and, with 50 watts on 40m last night, Victor logged VK3CWB in Victoria…just! The report of RST449 was probably generous from Maur given the current propagation conditions.

The recent 1A0C operation in Rome were logged at 50 watts from 40 to12m, using all three aerials and, just for fun, I popped back later for successful 5 watt QRP contacts on 15 and 17m.

This aerial will actually load up from Top Band to Ten but its short length will obviously make for poor efficiency on the lower two frequencies. 60m is a ‘no-no’ as very high Z.

Work is now in hand with the preparation of the earth system which is to be six steel rods each 6ft long, and hammered into the soil beneath the mast. A variety of existing ground radials are ready to be connected at the feed point“.