M5 x 16mm stainless button-head Allen bolts screw straight into to mounting holes on the rear of these excellent Fibox enclosures.

Off to the workshop to find, cut and fold a suitable 2mm sheet of aluminium and form it into the above bracket. I had a Male-Female-Female-Male PL259/SO239 join in my feedline anyway, where some idiot cut through the coax with a pair of edging shears earlier this summer, and I didn't want the choke too close to the antenna so this seemed the perfect place to insert it. So step one is to mount this enclosure outside. This is what my guide and mentor Ian GM3SEK recommends anyway, so I'm just going to push on with my plans at this point. Still, the plan was always to mount this choke outdoors, and then to potentially install a second one at the transceiver end of the coax as well. I'm not too concerned at this point, as the antenna is going to be raised much higher, and I'm only getting problems when using more than around 60W on bands where the SWR is less than ideal. All my USB peripherals began playing up - a sure sign of unwanted RF. Just what my RF choke was built to avoid. But there was a new problem which I didn't really expect.

Much better results than the vertical it has replaced. The antenna is not properly installed yet - it's awaiting installation of a second supporting mast, but I couldn't resist seeing if it was useable and it absolutely is. Apples should be compared only to apples, so I cleared the partial observation fluff from my head and decided to start any comparative tests from scratch using alternate fruit. Then came the antenna change to an End-Fed Half-Wave.

So all good and I was ready to run some more objective tests. Not sure exactly why that was, but less RF in the shack allowed better manual ATU tuning I suppose, and also less noise being transmitted with the data signals, I'm going to surmise. Much reduced noise levels, and also slightly improved reception reports when using WSPR and FT8. I was very happy with the results when using it in the shack on my Cushcraft trapped vertical antenna. Written by: Maintenance Guy Category: Feature ArticlesĪ few weeks ago, I posted an article on an RF choke I had built.

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