Tuesday, 12 August 2014

Filters for beacons

Today I built two 432MHz beacon low pass filters. One is destined for GB3UHF in Kent and the other for GB3NGI in Northern Ireland.
The filters were designed using ELSIE and the implementation is silver plated wire coils and paralleled ATC fixed capacitors and 6pF Voltronics ( I think) ceramic trimmer capacitors. The filters are assembled in small Eddystone diecast boxes with 17mm flange N female connectors as shown.

The measured performance of the filters matches the ELSIE predictions quite well. Insertion loss is below 0.2dB with a return loss of well over 20dB ( depending slightly on tuning for minimum insertion loss).


  1. Any idea when the Kent UHF beacon will be on-air?

  2. Not sure, Roger. Chris tells me it should be soon, bu no date given. GB3NGI may be on first