Stacked array for 70cms

You might have noticed in the last picture in the blog, not only was there an MA5B on the mast, but I also have a quad 70cm omni array.

 This is the Jaybeam quad array just after being purchased at Dunstable Downs

The aerial was spotted in the back of a pickup truck with a whole load of ex-PMR stuff, and was purchased at the princely sum of £35. Bargain!

This was part of the plan to develop the 70cm side of transmission for GB2RS, the news broadcasting service of the RSGB, which i read for most Sundays. I have been using a duplexer to simulcast from two transceivers on my colinear, but the opportunity for a catastrophic failure was huge, with a fault developing on the duplexer possibly dooming either of the transceivers to meltdown! It would also allow me an opportunity to run maximum UK power on the array, which could handle it easily without melting! This is something the colinear could just NOT do.

I am now looking for a serious UHF linear, which is not going to bankrupt me. If you hear of anyone that has one for sale, please let me know.

 

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 will 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.