Hi Bob

Thanks for your reply. We have a long way to go before I can set up a ham station on site as we are working full time on refurbishing the buildings at the moment. I have just given up my job in IT to work on the project so no income at present. That is making it difficult to save money to buy a HF rig but I'll get there. We are going to offer training placements for adults with learning difficulties and disadvantaged children on the farm. I love to see how happy they are around the animals. There is a 100' communication mast on site that I have permission to use, it is at the top of a 400' cliff above the sea so I should put out a great signal from there.

All the best.

Jon

Hi Martin

Thanks for your post and email. The  link is very interesting as this was a sister site to ours on Portland. I assume that the site was in use at the same time and just yesterday someone told me that he helped convert the guard house into horse stabled in about 1975 so the time scale is correct. Eham readers might be interested to read this link about the Troposcatter system.

If you or anyone else would like to visit the site please contact us via our website.

Thank you

Jon G2FHF

It wasn't an intercept station but a troposcatter cross-channel relay link, see http://en.wikipedia.org/wiki/ACE_High. That would explain the high security and the very large Heliax cable.

Thanks

Jon G2FHF

Thank you both for your help, I will look into both of those leads. The site was highly classified even though it is only a small site, about one acre. There are high security doors, air filtration and the whole building is a Faraday cage. I am planning a ham radio station for myself and visiting hams as it is a perfect DX location. It is 500 feet up above the sea with sloping ground to the sea on all sides. There are underground cable ducts and a 100 foot mast that we can use too. It really is a radio hams dream location. I just have to raise funds for a HF rig as I don't have any gear any more.

For more information on the site see www.fancysfarm.co.uk or search Google for Portland ROTOR.

Thanks again guys.

Jon G2FHF

I am trying to find information on an old USAF listening station on Portland in the UK. The site is an former cold war radar station and was operational between 1954 and 59 and was later used by the USAF. Myself and my wife now farm the site and I would like to set up a permanent special event station sometime but funds are very tight at the moment. I have been unable to find any information about what the function of the USAF building was but I have removed lots of very expensive heliax cable from there and found that were about thirty antennas feeding back to listening positions within the building. The electricity supply is heavily filtered too.

If you have any information or can point me in the right direction then I would love to hear from you.

Thanks

Jon G2FHF
jon@portlandbill.com

Sorry guys, I seem to have started an argument here, it wasn't intentional. I just wanted to see how the relay switching worked but I now have that information thanks to the TW Antennas website and their manual for download.

As for copying other peoples work I am not into that, I just like the idea and feel that the Sigma vertical dipole is not very efficient on the lower bands. It is effectively a 10m dipole that is centre loaded for the lower bands. My plan is to make it bigger and resonant for 20m then use centre loading for 40m and switched capacitors to bring it to resonance on the higher bands.

You may have seen my antenna review for the G2FHF Skyranger Pro antenna in the Verticals and Wire Antennas section. This was my own development and it worked well but I have now shelved that project in favour of this one. It looks like the SR Pro was copied by Eco Antennas in Italy here http://www.ecoantenne.it/product_info.php?cPath=21_27&products_id=136 but I can't be sure. I don't mind anyway as it's a free world and it's nice to see something come of the project.

Cheers

Jon

Hi Allen, thanks for the reply. I am building this type of antenna as a commercial venture. The Sigma 5 and the 40-10m version are too small to be efficient on the lower frequencies. They are effectively two base loaded mobile whips fed as a dipole. I want to build one that is resonant on 20m without centre loading then use coils for 40m and capacitors to bring it to resonance of the higher bands.

I have used this approach before with good results and hope to launch this antenna as a fully fledged commercially available product in the UK soon.

Thanks

Jon

Does anyone have a Sigma 5 type antenna or information on one as I am planning a homebrew version and want to know what size relays to buy. A picture of the matching system would be great. I am guessing that the highest current relays I can find would be good since they will be at the high current not high voltage part of the antenna. However the relays in my SGC ATU are really small so does it matter?

Thanks

Jon G2FHF

I have recently bought a second hand FT-990, which really is a fantastic radio. However I recently bought an IF filter, model XF-10.9-501-01, I bought the filter believing that it was for the FT-990 but can find no mention of it in the manual. Also I can't find any reference to this model on the internet.

Does anyone know which transceivers this filter will fit.

Thanks

Jon G2FHF