The antenna for 500KHz


This is my pump-up hilomast complete with 4m yagi, with added old 70cm colinear to give a vertical height of 12m. The whole mast is stood off on PTFE insulating blocks.

A top section sloping to about 7m makes and inverted L

The grey box next to the shed is the antenna tuning hut. The actual matching unit is below:-

Several signals heard initially, including OK0EMW at over 1600Km, Finbar GI4DPE is by far the most consistant, averaging 569, but is relatively close.

NOV application sent ot Ofcom, 13/9/07

On recipt of the NOV, on 26/9/07 I was able to work GI4DPE, GM4SLV (First GM to GM on 500KHz) and GI3PNG with relative ease, and could see my signals on the Birmingham Grabber (a remote reciever that is connected to a PC, and uploads near real-time waterfall displays of the received signals). several presently available on 500KHz are GM4SLV in Shetland (wideband and narrowband) ,

and from G3YXM in Birmingham. My own grabber is now also available much of the time (see link below). Others QRV occasionally, listed here

on 29th September 07I worked G3XIZ and GW4HXO

All QSOs have been on normal speed CW

I have had reports of readable CW signals from France, Holland, Germany and Finland.

Operation was limited in the winter due to working away from home, and high wind keeping the antenna lowered.

With the renewal of the NOV, and a higher permitted ERP, I have built a prototype FET PA, running 120W. Messy but it works well.

This gives me close to 1W EMRP.

I have had reports from a few more DX locations, and can see my signal on Marcus, DF6NM's Grabber in Nuernberg JN59NK

on 13th April 08, my signals were visible running QRSS3 in Moscow (Thanks to Andrey RN3AGC in KO85SV) Grabber (part time 500KHz)

Also seen in the Czech Republic (Thanks to Lubos, OK2BVG in JN88KS) and in Whitstable, Kent (my former QTH) thanks to Chris G4AYT



Experimental 500KHz Grabber (sampler) at GM4ISM

I would appreciate it if users only stay logged on when they are actually watching the grabber, as there is a possibility of exceeding my upload allocation with the present increased filesize.

This is a Softrock 455 KHz receiver retuned to 500 KHz, I & Q straight to the soundcard, processed by Spectrum Labs software which generates the HTML page

Now running on a ferrite rod antenna like the one below, mounted in 40mm drainpipe.

MF grabber antenna in plastic pipe just below rotator, orientated 135 - 315 ETN

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