Wednesday, 21 August 2013

New Tri Bander

Well the new 6m/2m/70cms vertical is finally in place, it was put up with the kind assistance of local amateur GW3FSP.

The weak point in these antennas is, in my opinion, the single nut or screw that holds the antenna to its support tube. You can install the brackets and clamp the antenna up as tightly as you like but if that screw fails you have a problem.

  You can just see the all important screw directly below the radials. The antenna itself is a "Sharmans" branded V2000. I imagine it is effectively a copy of the Diamond V2000, whether the quality is any different-time will tell.

The little Watsom W30 vertical I took down served me well, it is still in good order and I may use it as a backup antenna in the loft or even take it portable.

It is currently connected up to my Elderly 2 metre FM rig, although I dug out  the Yaesu FT857 which I use for portable work to test things on 6 metres and 70 cms. Indications are that this new antenna has a bit more gain on 2 metres plus of course gives me the ability to use the 6 metre band, although I have pretty much missed out on the sporadic E season!!

I am still debating whether I can justify another rig in the shack to cover 6/2 and 70. I could use the FT857 I suppose that normally stays packed away for the odd portable outing. The funny thing is I was never that keen on the 857 in the shack, its display is rather small and it is a little fiddly to use in my opinion. The Icom 706 I have in the car is better in that respect. An Icom 706MK2g would be nice, or even an Icom 7000 (but these seem very expensive). In any event I will also need a duplexer to split between 6 metres and vhf/UHF

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!