Small Job develops into a Marathon.

It has been a bit rough the last few weeks with periods of high winds, which necessitated the luffing of the Tenna Mast in the back garden. In fact I dropped it over in a bit of a rush one dark night and in the process forgot to slacken off the feeder at the same time as taking the tension off the halyard for the wire antenna, the centre of which is hung from the tower. In the process of dropping the mast, I ripped the feeder out of the plug in the balun!

The Tennamast with The MA5b, the Alpha Delta DX/CC wire antenna, 70cm 4 dipole array and Weather Station!

Today I had an hour to spare and thought I would put a new plug on the feeder and seal it up with some self amalgamating tape. Following the work on the feeder, I performed a quick test for impedance and SWR on a dummy load before putting the mast up again. At the same time, I replaced batteries in the weather station which has been down for a couple of months, but as I went to put everything back, I noticed that the 300 Ohm feeder for the 1/2 size G5RV had become disconnected from the RG58/twin feed adaptor (I use this for a listening antenna for a noise canceller). Upon closer inspection corrosion was responsible for the parting of the ways of the twin feeder from the crimped eye connections in the adaptor. Another repair later, plus re-positioning the beam on the stub mast (it had twisted out of alignment in the wind), and the antenna farm was back in business.

What was going to be a quick plug replacement ended up being nearly 2 hours worth of faffing around, but at least everything is up and running again now.

Sick Icom IC746 repaired

I have been dreading it.. I have put it off for ages, Yes the 746 has been fixed.

A few months ago, I had been using the radio (my main HF rig) and it started making funny noises when the internal tuner tried to match the aerial. It also would not match.

I looked up on the internet for possible issue and solution and discovered that the radio had a known issue with the tuners motors, where a sonic weld fails between the ferrite core and a spindle and washer. The thing is I had a workaround which was to use an external manual ATU, so knowing just how many screws I would have to remove just to get to the motor, the job got put off for some time.

I finally bit the bullet because of the way I operate. With band conditions quite lacklustre at the moment, I frequently band hop, which necessitates frequent re-matching of the aerials. It was becoming a real drag keying up and manually tuning all the time, so I though “damn it, lets get this done’. First thing was to get the video I found about this repair up on my iPad. ( https://www.youtube.com/watch?v=UdY6RhNOCWg ) and then it was a matter of removing over 30 screws and de-soldering the aerial sockets from the board before I could get to the motor and fix it.

The dreaded stepper motor, note the crimped ends which needed prying out.

The motor was extremely difficult to get apart without either damaging it or impaling my hand on a screwdriver, but eventually I got into it and glued the bits together, reassembled it all and hey presto a few hours after I started the 746 is back in action and working perfectly.

I think my new years resolution is to get things done and not let things build up. You never seem to have enough enthusiasm to fix something when you know what a ball-ache it is going to be to do it and the jobs then start to pile up and you never get around to doing them.

 

Aerial rethink Part 2. Cushcraft MA5B

After using the radiator of the Jaybeam as a dipole for a while, I was really missing the Cobweb, as it provided more wavebands than the Jaybeams 20m, 15m, and 10m. I was also considering just keeping the cobweb as a backup and getting a mini beam with some gain.

It would have three advantages. Multiple bands, Gain and a reasonable front to back ratio. Ever since I have got my licence, I knew that I fancied a Cushcraft MA5B. This is a three element trapped beam with capacity hats. Whilst not offering the same performance on all bands, it is probably the biggest all around beam I can get away with at my QTH, but try as I might, I could never find one at a price that I could afford.

Well in July 2017, that all changed, when I heard that Roger Mansell Williams, M0RMW was selling his bungalow and downsizing his setup in a move to Selsey Bill! He was offering his MA5B for just £50, which is a considerable saving over a new one, which cost upwards of £530! All I have to do was to go down to Farnham in Hampshire to take it down.

It came down really easily, it had been well looked after and was in really good condition. It fit OK into the jag with the back seats folded down. Roger was a gent and provided a manual for me to piece my new jigsaw puzzle back together again. It was not too difficult as I put insulating taped codes on the elements as it took it apart to aid with reconstruction!

Waiting for a couple of days for a lull in the thunderstorms, I managed to whack up the beam in a few hours, consigning the Jaybeam radiator elements back to the pile of aluminium down the side of the house, which is the Tribander. Initially the I used the mini beam using the internal matcher in the Icom and it worked well, out-performing the wire antenna by at least 3S units and being far less susceptible  to noise. In increase of the signal to noise ratio meant I could hear station I just could not hear before. In order to increase efficiency, I will go through a tuning session with the antenna analyser. This will increase transmit efficiency and reduce losses to make this acquisition a real bargain and my find of the year.

Broken Cobweb causes a rethink

A few weeks back the XYL was complaining that that my tower, which is attached to the side of the house, was making a god awful racket when the wind got up. I ended up getting out of bed in the middle of the night to lower the mast and luff it over in order to stop the rattling which was being transmitted through the walls! The only problem was, it was dark and I did not see the spreaders bow as they hit the ground due to me luffing the tower over too much. I now have a cobweb with two broken spreaders and the support for the balun box also snapped.

Previous aerial setup before the damage!

Previous aerial setup before the damage!

Following the the damage, I decided to push a bit of kit into action that I have had down the side of the house for some time. I actually have a three element Tri-Band Yagi, which is too big to put up in it’s entirety, so I decided to mount the radiating element only in the form of a tri-band dipole.

The new HF setup!

The new HF setup!

After putting up the dipole, it was checked with an analyser and it all checked out great with little adjustment required. It was a little more noisy than the cobwebb, which is well known for its very flat signal pattern. It was giving me 2-3 S units over the wire antenna which was weird as I was not expecting such a big difference. It has given me a good reason to bring the wire antenna down and give it a good checking over, but that as they say is another day! I have had contacts into Russia, Saudi Arabia and even Iraq in it, so it must be working OK!

In the meantime the tower was put back up with a bicycle inner tube glued around the part that slots into the bracket on the wall. This has killed the rattling and hopefully I will not have to get up in the middle of the night again!

Shack re-organised for Christmas

Most people are spending time getting ready for friends and family descending on their house for the Christmas festivities, but yours truly, under orders from the station manager has been busy trying to sort out the home office, which doubles as the Shack / Workshop / Broadcast Studio.

The main issue was that I had a mammoth sized broadcast mixer taking up a huge amount of space and all the Radio gear was piled high on my work desk, which was not conducive to the day job. I therefore took the plunge to sell the broadcast desk (I have another in garage if I ever need to do some broadcast work anyway) and utilise the space more wisely and this is what I have come up with:

Shack

It certainly has cleared up a huge amount of space on the desk & I can now get to work sorting the rest of the office! The big pipe snaking up to the window is the Air Con which is essential during the summer when all the gear plus no less than 5 computers can be on at the same time.

DMR, the voyage begins

OK, last week I took delivery of a TYT MD380. It is pretty much the same radio as the TYTTytera / Retevis, but with just a different badge. Apparently this is one of the last batches of TYT’s available from the supplier in Germany, and the next batch of radios he is getting will be Retevis. He said that the firmware is basically the same to, but might just be a newer revision.

I plugged mine in, downloaded the latest codeplug from LEFARS and updated it with my ID and copied into the radio. I switched it on expecting a rush of DMR traffic, but was disappointed not even being able to open the Barking repeater. A bit of home-brewing and I knocked up an SMA to PL259 connector, plugged in, connected to my collinear and it all burst into life. I was amazed at how easy I could get into NS (North Surrey) in Caterham, and of course Barking was now available and even better, the biggest surprise was Rochester (IK) which was giving me the highest signal levels in the area, even more than Thurrock (SE) and even though the coverage map does not even feature anywhere near my QTH in Hainault .

A weekend away for my daughters wedding in Devizes saw me test out the radio in the van, hitched up to an SG7900 antenna on the van, I easily got into Bristol (BS) while the Reading repeater remained elusive! In fact I managed to get into BS all the way out near Upavon, which was some feat!

It just goes to show that the coverage maps are a nice guide, but no-where near accurate! From the van I managed to have decent copies with someone in Ashford whilst near Heathrow, which I would never have been able to work simplex on 2m. So for communications on the move, it is undoubtedly a great mode if you want to talk to someone and not have the same challenges of working analogue modes. I will always keep the VHF / UHF and HF gear in the van though as that is my primary interest, but for a decent quality chat on the move, then DMR really does have its place.

I am also going to purchasing a dedicated antenna for 70cm now as well! Stacked dipoles so I can use it with a linear for GB2RS?