Mid Warwickshire Amateur Radio Society Interests and Activities

Don G4CYG had brought along the 400 watt linear he had been given (some years ago) by Ron G3XTN and some considerable time was spent in simply admiring Ron's workmanship.   MWARS members were also mightily impressed by the diary of calculations and measurements kept as construction progressed.

There is a problem with one of the valves and Don had made some preliminary measurements which suggested that there were considerable differences between manufacturers as regards the mutual conductances and suitable working voltages.  The output stage has 4 valves in parallel and an intriguing feature of the circuit was the fact that their grids, are (for AC) at ground potential.

See this site's  "Homebrew" pages for further information.

The "mystery station" transmitted on 145.225 MHz (starting at precisely 18:00 BST) and, after moving to two further locations ceased activities at 19:35.

Three stations participated: G4CYG; G0FBY and M0RJG.   The first 'retirer' could get no directional information at all, and felt so sorely in need of an attenuator he went back home to try to find one.     As it happens this might have been just a bit of bad luck because all-unknowing he had chosen to operate barely a couple of miles from the transmitter (probably within line of sight),   i.e. a situation where an attenuator is essential.    There was a chance that waiting for the next transmission from a much more remote location would have solved the problem!

The remaining stations also were not as fortunate as they might have been.     With just two receiving staions only one 'base-line' is possible (with three stations there are three) and it so happened that for two of the three transmissions the intercept angles were very acute, making errors inevitable.

A query has arisen as to the suitability of the HB9CV for DF purposes;   peculiar 'squint' properties were again noticed,  triggering fresh enthusiasm for some more tests like the ones done at the'picnic' event 4 years ago.

Results will be given on air during the Kenilworth Wednesday Net on Wednesday 22nd April.

Just two members were able to get together to set up an HF station and have fun simply playing radio on the first fine day we have had for ages.

We were located near the village of Stoneleigh (locator IO92FI), with the nearest computer far enough away to make listening on the bands an interference-free delight.  The surroundings were delightful too.

Earlier we had set up one antenna support on a convenient tree .

And expert catapulting got the halyard aloft.

The 'snagging-free' method of splicing the 'leader' to the halyard (2.5 mm AC mains cable) is shown here .

On the day itself it took G4CYG and M0JDB about 45 minutes to put up the antenna (for this occasion a G5RV).  It will be quicker next time.

The lower end of the (roughly) North-South dipole was about 6 metre agl; the other was supported by the convenient  tree shown above, about 18 metres agl.  The 'fix' to the tree being courtesy of G4PKT and his skilful work with the catapult.