Antennamabob Swap

Well,

Having played with the antenna I installed back here  for a while now, I have decided to go back to the Cushcraft MA5B that I had previously.

I have found that the Q52 antenna had little or no front to back, furthermore there was a switch on the control box that was supposed to "remove" the reflector to make the two element antenna into a dipole, whilst this altered the SWR very slightly, I found no difference whatsoever to signal strength from the front or the back of the antenna. Extended tests in both dipole and beam mode showed no signal strength difference from the front or the back of the antenna. Tom, N6BT, for reasons only be-known to him, chooses to ignore my email requests for technical support - so I haven't been able to get any. I did climb a ladder and conferm that I could hear the relays going click in both the director and reflector when the band switch was altered on the control box, I also double checked the control box to antenna wiring - not sure what else I can do to test the setup.

More recently, 500W of CW to the Q52 antenna has caused the relay box on the driven element to fail. Investigation shows that there are signs of arcing on the element connections - this antenna has proved to be a very expensive mistake!

I have also been having some concerns recently over the amount of weight on the mast and it's ability (or inability) to hold everything. I've therefore designed myself a new mast arrangement, there is no telescoping in this design, but it's much stronger and sturdier (and heavier) than the previous arrangement.

Here we are in the midst of the swap:

The Base section of the mast is 2.5 inch, thick walled box Aluminium, and that is then topped with a 48.3 mm OD stainless steel tube to the rotator cage. The stainless tube drops into the box section with a 2 meter overlap - the two items are bolted together in opposing angles so it can't move or turn. The rotator cage is made from galvanized steel and was manufactured by Tennamast. The stub mast is currently a 48.4 mm OD steel scaffold pole, but I have ordered a 3 meter long aluminium replacement to try and reduce the weight a little.

The mast all pivots and is lifted into the vertical using a winch and steel cable.

Once I have the replacement stub mast I will put back the VHF antennas and all will be well. The rotator is a replacement and is the G-1000 from Yaesu.

Here are the SWR curves from the MA5B as installed:

local conditions.

I've finally sacked him for being useless!

Well,

You may remember the trauma I sustained trying to stop the back of the house and the sitting area below getting constantly covered in bird ****.

At the bottom of this post was where I recruited the services of Oliver the Owl:

http://g0mgx.blogspot.co.uk/2012/08/top-band-what-happens-there-then.html

Oliver has proved to be quite useless apart from serving as a great vantage point for the birds to perch... so today I have finally got round to getting rid of him.

Instead I asked on one of the eHam forums here:

http://www.eham.net/ehamforum/smf/index.php/topic,90940.0.html

and as a result have got some mirror finished plastic stuff and some garden twine and have ended up with this:

If you look closely you will see that there are five shiny mirrored things suspended between the two antennas.

Time will tell, but I think I might have cracked it!

Sneaky, egh?

Antenna Complete!

Well,

Perhaps you remember the antenna I started to put together last weekend and then realised that the bits for the 6M sections were the wrong size? It was back here:

http://g0mgx.blogspot.co.uk/2013/05/thatll-never-work-will-it.html

The correct parts arrived today to complete the antenna, so the tower has been down again. I've just flicked through the archive from "Antenna Cam" and here's me up the ladder fiddling with the top bracket prior to dropping the tower down:

If you look closely in the above image you can see me fiddling, but you can also see that the closest element on the HF beam is a bit "out of bonk". Here's the antennas back up again and I've fitted the parts to the 4/6M beam and also straightened out the HF element:

And finally here's an image of the antennas back up with the weather a little clearer and them pointing back to the SE:

The 6M part of the top beam is no longer resonant at 55MHz, but seems to be a good match on the 50MHz amateur band!

It's perhaps just a little too short but it's more than acceptable for my requirements; the resonant point on 4M or 70MHz hasn't moved.

Good, egh?

Where do the knots come from?

Well,

I've been checking some wiring today; there's a great deal of it in my shack and it's always in a spectacular knot!

I saw some SWR movement during the XE contest at the weekend and thought it was worth investigating... as normal I have found a PL-259 connector soldered in the most appalling way possible - I suspect this may be the culprit so it has been duly replaced.

Whilst I was doing this I decided to draw a diagram of what is connected to what -  was getting in a bit of a muddle, so here it is:

So at least I have a known reference point to look back at now.

Not very exiting, is it?

Changes at the Top!

Well,

I've not been overly happy with the arrangement to adapt from the top section of my new mast (which is 2" OD box section aluminium) to the 2" OD pole that holds the rotator. This was originally a aluminium plate that had "U" bolts for the pole and some nuts and bolts that fitted through the plate and then through one wall of the top mast section. When the wind picked up there was the risk of:

1. The whole thing folding back on itself;
2. The plate twisting.

You can see the original plate in this picture here:

Now, as I was concerned about this before the changes today, I had actually inserted a smaller diameter pole inside the rotator pole which was secured by a bolt that passes right through the rotator clamp. This smaller pole extends through the top rotator stub mast down into the top section box part of the mast itself. This (I was certain) would ensure that the plate didn't fold back on itself in high winds.

So, what I have done today is use a piece of 3" OD aluminium box section to create a kind of sleeve that sits over the rotator stub mast and the top section of the mast itself, this sketch kind of explains what I've made:

And it looks like this in reality:

And this is a close up of the top section of the mast itself where it enters the new sleeve:

And here you can see how I have made larger (looks like using my teeth) holes in one of the walls of the sleeve to access the bolt heads to ensure the pole and the mast top are hard and fast against the side wall:

and this is the underside of the same bolt:

So, all in all, I think this will enable me to sleep better knowing that the antenna isn't about to land on the back of the house!

What do you recon, better egh? Cat's not impressed, seems to like the new radio though:

It's now Official; I am completely nuts

Well, following a recent street party to celebrate the Queen's Jubilee; a discussion with my neighbours about antennas ensued. The conclusion was that whilst they are somewhat intrigued over what they are for (one neighbour thinks I am a spy), they are not "bothered" by them in the slightest.....

This got me thinking....

The past two days have been spent making some changes here to the antennas; so the first job was to bring down the main HF antenna. If you have been following this blog you may remember the last time this came down, it involved bailing twine and some knots, the details are here:

http://g0mgx.blogspot.co.uk/2011/11/so-how-can-it-possibly-go-wrong.html

So we tried the same trick again (with the ever patient Vince, G0ORC):

Remove the U-bolts holding the mast to the T and K brackets... then start to tip and let the bailing twine out slowly...

And a bit more....

So here is the antenna on the floor:

So now I needed to remove the pole(s) and the T & K brackets holding it all against the house. Once this was complete I could install the new mast. I got this mast from Gary, MM0CUG he's custom made it for me.

The first job was to unpack the box of bits:

The I had to fit a new top bracket and drop a plumb line:

Then I had to mount the base bracket and line it up with the top bracket and plumb line. I cheated a bit here and actually used the mast itself to line the two parts up:

This is the bottom bracket, not securely fixed yet - just look at the brick dust:

So once the mast was in place OK, I then needed to build the new antenna - it's an MA5B from Cushcraft, here are the elements beginning to be assembled:

And the new rotator and boom on the top of the mast whilst tilted over:

Here is the first element on the boom:

And then the whole thing up in the air:

What do you recon? Insane, hugh?