An alternative to the 6M7JHV antenna for 6m / 50MHz
Environment issues

I have had a stack of one sort or another up for nearly 20 years and I have never really had a problem with what I'm calling 'environment' issues i.e. issues relating to the physical aspects of the antennas, for example wind!

There is now doubt in my mind that bayed antennas can be considered to be 'high maintenance' toys compared to stacked antennas.

Typical wind forecasts

As discussed on the 'baying page' I hope that I did as much as I could to support the bayed antennas to prevent wind damage, however each antenna is only supported at its centre of gravity to a semi-flexible glass fibre boom. This arrangement does allow the each antenna to 'flex' or oscillate vertically in high winds putting considerable rotational stress on each end of the fibre glass cross boom. Therefore it makes sense to consider how the antennas can be best protected from damage in very high winds in addition to lowering the tower.

My solution is as follows. Normally, the elevation rotator does not allow the antennas to go below the horizontal but I reprogrammed mine to dip down (like a Harrier jump jet!) by 35 degrees as can be seen below. The land behind my tower rises by six feet which allows me to reach a pair of normally tied-up ropes which are undone and tied to fences. This quick and effective method should, I hope, prevent serious damage in high winds. The ropes are tied together again when the antennas are returned to their normal horizontal position.

Tying down the antennas in a high wind.

As I will want to raise and lower the tower much more often when it is windy. I decided to end 20 years of doing this manually and invest in a robust motorised winch available from Goodwinch Ltd.

The motorised tower winch

However, the winch is VERY noisy which drove one of neighbours to complain bitterly about the noise when I lowered the antenna at 01:30 in the morning. Clearly, I have to do something about this!

Quietening the motorised winch!

As the winch was shaking the whole tower, the first task to make some rubber mounts. I bought some engine mounting rubber supports that had a 10mm inside hole (sheathed in metal) and an outside diameter of 21mm. I also bought some large diameter 8mm thick rubber washers - all from good 'ol Ebay.

The bits and pieces to build the anti-vibration mount

I cut the engine mounts down to a thickness of 8mm and assembled them as shown below.

After drilling out the three M6 clearing holes to 21mm, the cut down engine mounts fitted quite snugly.

The cut down engine mounts

Putting the bolts through

Everything is now ready to mount the winch back on the tower.

and adding the mounting plate.

To reduce noise even further, I have built a box out of 20mm MDF board and lined it with carpet. Now you can hardly hear the winch at all!

The box used to suppress the noise from the winch.

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