Sunday, 8 June 2014

Getting on the web...

Some weeks ago I bought a mounting kit from Amtools to build a Cobweb antenna. After a couple of weeks wait whilst I treated myself to an automatic center punch from the far east, I took advantage of the good weather today to spend time in a dimly lit workshop drilling holes in aluminium plate!

The photo above is of the completed mounting plate from the underside. The one below is of the top side, where the spreaders will be fitted

I now need time to add the spreaders and the antenna elements. This is likely to be some weeks, which gives me time to get the balun made!

I also now have roof bars on my car, after 'repurposing'  the ones bought for Julies Ford Focus which she no longer has. One convenient aspect of this is that I can use the car as a mast base. But, before I can, I need to build a bracket that will allow me to clamp the mast to the roof bars.

As it happens, I discovered I actually have quite a few more U clamps than I realised! Two of the smaller ones will nicely clamp the bracket to the roof bar. A couple more larger ones are needed, plus some suitable box section aluminium tube, to make the bracket and mast clamp.

I also installed a 4ft ground rod underneath the 20m vertical (a.k.a Sams flagpole!), and finally got around to testing the antenna with the MFJ-259 analyser. It does seem that ive unfortunately cut it a tad short, and its resonant around 13MHz. No big problem, a couple of turns at the base for a loading coil will correct that. But, at 20m, and with just the ground rod, the VSWR is about 3.5:1, well within range of the remote auto-ATU I intended using with it!

So, what about actual radio? Well, today has been very warm, in fact too hot for me! So, in between a bit of gardening, antenna work etc, and before and after karate, ive had a potter about on air. Being the D-Day weekend and also Museums on the Air, theres plenty of special event stations about! Ive time for a few more before bed, and at last am enjoying the LED shack desk lighting I installed!

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