Wednesday 14 August 2013

Antenna Work

Last weekend the weather was good here so on Saturday I started some antenna work.
Currently one end of my HF doublet and my VHF/UHF vertical is supported by this pole.

I am not sure how well the picture captures it but that bracket and pole are not quite vertical!! When I moved here in my enthusiasm to get on air I put the bracket up on a cold wet autumn evening and well...........I could have done a better job.

I have now installed a T and K bracket and will be putting a thicker , larger diameter pole up as my new mast. The old fitting will then be taken down.

As part of the antenna work I will be installing a new vertical for 6m/2m and 70 cms. I thought I would assemble the new antenna in advance and set it up on a short pole in the garden just to test it. A local amateur had a similar antenna and found the SWR was high on 6 metres and in order to get it right had to shorten the 6 metre radial.

I used my Yaesu FT857 with an external SWR meter to test the antenna. This proved interesting, the 857 has a built in SWR meter, its not calibrated, just a series of 'blobs' on the lcd but its an indicator I suppose.

On 6 metres I had an SWR reading of 1.6:1 on the external meter, not brilliant but acceptable so I wont be trimming the radial on my antenna, oddly the 857 meter was showing a perfect match (no blobs) and 2 metres both the external and 857 meters showed a good match. On 70 Cms the external meter showed again a good match, the meter on the 857 indicating quite a high SWR. It seems that the built in meters are not really that consistent, something I also noticed with the Icom 706 I have in the car.

Anyway the vertical is ready to go up on a new mast once I have some more time and some decent weather!


  1. Oh yes trimming an antenna for a happy SWR and yes 1.6:1 is not to bad at all. I have in the past tried to get an antenna as close to flat as I could. In such an effort I have either ended up trimming to much..and had to start over again. I find an antenna analyzer work great when working with antennas and the SWR, I have the MFJ unit and it works great and saves time.....and antenna wire!

  2. Hi Mike

    I think an antenna analyser is a great idea but they are not the cheapest of tools! I have seen the MFJ untit and it looks really useful. Would be good for adjusting portable antennas like the Buddistick in the field too.
    Perhaps I should put one on my Christmas list for this year!



  3. Hi Kevin

    Like Mike I too have one of the MFJ analysers and wouldn't be without it. GDO's and SWR meters are fine but antenna analysers make adjusting antennas so much faster and simpler, especially if one uses the old dodge of just twisting the excess wire loosely back around the antenna wire rather than cutting it off completely.

    New they are a little expensive, but they are available on Ebay at a more reasonable cost and as you say one would make a wonderful Christmas present.


    Kevin G6UCY

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