GB3RAL on-the-air this weekend

GB3RAL is currently operating on 5.29, 28.215, 40.05, 50.05, 60.05 and 70.05MHz. It would be interesting to know if anyone not local can hear them all.

All the VHF systems are on temporary antennas that John G3VPW and myself put up this afternoon [Friday].
28.215 is a very old system that we hope to replace soon. 5.29MHz has been running on the same temporary antenna for 3 years.

We need someone to make us some antennas.

To make the systems permanent on the VHF bands we need professional quality antennas. I cannot build these myself. They also need to be good looking too as they are prominently located. They have to be very strong because they will be 20m up on an exposed site and access for repair will be difficult requiring a harness etc..

It was also found that the antennas de-tune each other when stacked. This was as expected but unfortunately the 40MHz antenna was detuned too far for the gamma match to correct and has a 3:1 VSWR as a result. This implies the antenna array provided should cover all 4 bands in a fixed unit so these inevitable interactions can be taken care of at the design stage.

Currently the 5.29MHz beacon is using a wire dipole.
The 28.215MHz is using a long vertical. The VHF beacons are using Halos stacked on top of each other starting at stepladder height. Because of poor matching the 40MHz and 50MHz beacons are operating through attenuator pads to protect the amplifiers.

TX Powers are:
5.29MHz 10W.
28.215MHz ~10W
40.05 MHz ~3W (limited by match)
50.05MHz ~3W (limited by match)
60.05 MHz 5W (limited by drive)
70.05MHz 10W

Mike
Email: M.J.Willis at rl.ac.uk

Related URL’s
GB3RAL and OZ7IGY
http://oh2aq.kolumbus.com/dxs/beacon.html

GB3RAL now licenced for 40 and 60 MHz
http://www.southgatearc.org/news/july2007/gb3ral.htm