[G8vsjDave]

When I saw the title of this thread, it immediately reminded me of a project I became involved with back in the late 1980’s.
I was working for a major UK electronics company, in their special projects division, designing CCTV systems for military, scientific and industrial applications.
One of our more simple, and what should have been straight forward projects, was to supply and fit a ruggedized CCTV camera system to several Royal Navy type 42 frigates The camera was to be mounted on a point quite high above the bridge and looking to the front of the ship, and connected via a co-ax cable to a single ruggedized monitor on the bridge. The installation seemed to go well, and on time, but a few days later we received a phone call to say the picture from the camera went off when the ships radar was switched on.
After being passed from pillar to post I finally got to speak to a member of the crew who was able to describe the problem. It seemed when the radar was switched on the camera picture went dark with only noise showing on the monitor screen. I guessed the camera’s auto iris was closing down due to interference from the ship’s radar, and that some extra screening and de-coupling capacitors would be the answer, and a few days later I found myself driving to Portsmouth.
When I arrived I was driven to a remote part of the docks where the frigate was moored and the first thing I noticed was a HUGE rectangular, parabolic radar array mounted on the ship. To my untrained eye it seemed totally out of proportion with the ship and made it look top heavy. Then I noticed what looked to me like band III dipoles mounted at the focal point of the parabolic array. Without thinking I blurted out “that’s over the horizon radar” – the two men escorting me just looked at each other, gave me a filthy look, and said NOTHING.
After I was handed over to ship’s crew and my silent escorts left, I set about installing the modifications to the camera’s auto iris circuit – three of four .001uf capacitors and a copper screen over part of the circuit, then, up to the bridge to talk with their technical officer. I explained I was unable to test modifications, and by-the-way, was this over-the-horizon radar? To my surprise, he replied “Oh yes, but we can’t power it up here, if we did it would cause major interference with Irish television”. Then he proceeded to flick a few switches, the band III array started to rotate, radar images appeared on screens, and apart from a few sparkles, the picture from the camera remained stable. I was then treated to a demonstration of the radar, a tour of the ship and later, taken down to the ship’s bar, to celebrate the working camera system, and all this time I was wondering what effect all this was having on Irish television because the radar was still on. After several celebratory drinks, my dumb escorts re-appeared and I was taken back to the port reception area, and from there, made my way home.
The following day I made some ‘discreet enquiries’ and was eventually rewarded with an anonymous phone call from a man claiming to be one of the design engineers involved with the OTH radar. He did not tell me much, but he did say that several ships systems had to be modified to cope with the radar which was based on a pulsed klystron and that the output was a “very dirty” 220Mhz.
Dave