144MHz EME with a WB2HOL Tape Measure DF Yagi!

In a moment of madness during the EME contest on 12 and 13 November 2005 I decided to have a listen on EME using my WB2HOL 2m DF yagi. This little antenna is made from a steel measuring tape which makes it excellent for fox-hunting. The elements just bend when you take it out of the car or run crashing through undergrowth looking for the fox.

I stuck the handle of the yagi into some plastic pipe, hooked up a length of LDF4-50 to run back to the rig, propped it up using a garden deckchair and pointed it at the moon.

The first station I copied with this antenna on Saturday was Dmitry RA3AQ calling CQ using WSJT JT65b. Having heard him I couldn't of course resist giving him a call and much to my suprise he heard me too. Unfortunately we didn't manage to complete the QSO.

I wasn't able to be QRV again until Sunday evening. Soon after his moonrise I heard Dave W5UN calling CQ and almost fell off my chair when he came back straight away to my call.

It was a textbook random JT65b EME QSO with no missed periods and we exchanged O reports and Rs. Easy!

Here's a WSJT screengrab of the QSO at my end.

I then went onto ON4KST Chat and Dmitry RA3AQ asked me to have another try with him. This took a little longer than the QSO with Dave, for two periods I couldn't copy him, but by EME standards it was still easy:

Here is a screengrab of Dmitry received on the 3 element at my QTH

Dmitry emailed me a screen grab of my signals received at his QTH.

The WB2HOL yagi was built to the dimensions given by Dave G3ZOI on the Basingstoke ARC web site.

The SWR using the hairpin match was 1.2:1 without making any adjustments to the dimensions. A length of RG-58 was coiled round the boom as a balun and the boxes behind the reflector are a digital compass for taking DF bearings and a series tuned circuit for nulling signals when DFing close in to a transmitter. The nulling attenuator box was of course disconnected for these QSOs. The rest of my station was a FT-736 with 3SK97 preamp in the shack. I was running 400 watts output from a home-made amplifier using a pair of Russian GI-7b triodes. The feeder was a 17 metre length of Andrew LDF4-50. The yagi handles 400 watts without any problem.

I also heard and called KB8RQ and RU1AA with this antena but only managed to get a QRZ from them. Sam RN6BN was an extraordinary signal peaking at -18dB and audible in the loudspeaker. He would have been easily workable but I had already made a QSO in the contest with him using my "big array" which is a 9 element Tonna! Gerald K5GW was also a great signal. I had not heard him before.

Thanks to Dave W5UN and Dmitry RA3AQ for building excellent EME stations which make this kind of fun QSO possible. Thanks also to WB2HOL for the original yagi design, to Dave G3ZOI for the modifications he has detailed on the Basingstoke ARC web site and of course to Joe K1JT for WSJT.

Paul G4DCV Email: paulATg4dcv.co.uk (replace At with @).