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Old 22nd Aug 2017, 12:55 pm   #21
mole42uk
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Default Re: Rampisham: All Gone bar One...

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destroyed by fire. He said that normally a fire would have been quickly extinguished using a fire extinguisher before causing much damage, but because some of the younger technicians had been caught playing with the extinguishers, a manager had had them locked up (the extinguishers, not the technicians!).
Obviously a management error, he should have locked up the technicians.
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Old 23rd Aug 2017, 9:30 am   #22
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The guys changing those coils must've had good faith in the isolators.
Indeed... And that of applying the earths before going in there. You couldn't just 'dive in' without going through the interlock / isolation / earthing procedure (filament supplies excepted), and there were several points of isolation.

If you look at the attached pic I took in '90, you'll see a big black handle top-left of photo (Sender 35) and an identical handle in the centre (Sender 36). These were known as 'X'-Bolts and were the point, on the older transmitters, at which the supplies were broken and the earth applied before entry.

Interlocks and earthing straps / mechanisms were inspected and tested every three months and had to be signed as such by the duty Senior Transmitter Engineer. Each sender had its own interlock book.

The filaments supplies could be dangerous. Only 10.7V, typically, but of such low impedance that 2000 Amperes could be drawn from a short-cct. An incident occurred at Skelton where a spanner was dropped across the fils bus-bars, melted instantly and the rotary converter downstairs barely missed a beat!

I would take my steel-banded watch off before band-changing the BD272s with the fils on, as we sometimes did under a 'Note 8' (on-air as soon as possible).
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Old 23rd Aug 2017, 10:18 am   #23
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Default Re: Rampisham: All Gone bar One...

The Dorchester transmitters were a well known landmark when we moved down here in 1970 as were the row of elm trees that formed the splendid entrance to Dorchester coming from the west.

I have never seen so many antennas, it truly was an aerial farm covering possibly a hundred acres or more. Yes the transmitter building subsequently became a printing firm which was there for a number of years, I can't remember what it is now but those cellars sound interesting.

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Old 23rd Aug 2017, 11:19 am   #24
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I can't remember what it is now but those cellars sound interesting.
They may have been used to house cooling and ventilation plant, rotary converters for the transmitter supplies, and programme input equipment, as they were at the UK BBC HF transmitter sites (but not Woofferton: no cellar there).

They were 'crypts' in BBC-speak.
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Old 23rd Aug 2017, 12:43 pm   #25
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Default Re: Rampisham: All Gone bar One...

Just been past Rampisham, can confirm that 2 of the original towers still stand and one modern short stayed mast in front of the transmitter building still stands.

One of the towers is further back on the site (presumably the one with the Hooke relay) and one near the front with what looks like mobile phone folded dipoles on arms mounted to the top.

Also slightly visible (from the car) were a few fallen and crumpled towers. They looked quite sad.
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Old 23rd Aug 2017, 12:59 pm   #26
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Default Re: Rampisham: All Gone bar One...

Do we know anybody who worked there or could organize a trip for us to see the transmitters before they are scrapped ?
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Old 23rd Aug 2017, 3:56 pm   #27
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Default Re: Rampisham: All Gone bar One...

The transmitters have been gutted and the useful stuff deployed elsewhere. Babcock sold the site shortly after the last broadcast went out - don't know who the current owners are.

The 'old' BD253 senders, S35 and S36 were scrapped in 1991 and their floorspace converted to offices and a conference room (you can't have too many conference rooms!).
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Old 23rd Aug 2017, 8:15 pm   #28
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I visited Rampisham back in about 1995. It was truly awe inspiring we went out to the aerial farm whilst programs were going out and we could hear the modulation coming from the metal box sections of the feeders. I remember that I could hear BBC world service as a background to radio one on 1053Kcs at night sometimes! Rampisham had its own 33kV supply of 2 circuits fed from different points on the grid one at Yeovil and one from somewhere in Devon. I know that a friend of mine has put a microwave internet relay on one of the remaining masts. So I think one must or will remain despite the fact that the rest have fallen
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Old 24th Aug 2017, 9:38 am   #29
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I read in the local paper that one mast had been retained as a nesting site for Peregrine Falcons?

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Old 24th Aug 2017, 10:55 pm   #30
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Default Re: Rampisham: All Gone bar One...

Hello Russell, do you know what's left in the way of LF/MF/HF Marconi transmitters in the UK these days? Being ex-Marconi I still marvel at how long some of the gear (of all kinds) has lasted around the world. I'm on holiday not too far from Skelton and I was just thinking about the old days this afternoon.

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Old 24th Aug 2017, 11:44 pm   #31
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Paul,

Woofferton still has a couple of HF broadcast BD272 transmitters on the go, and four B6124s too. The other HF transmitters are RIZ doing analogue and digital (DRM) broadcasting.

Then there're the two Arqiva BBC Radio 4 B6042 transmitters at Droitwich, of course. I have no idea what other Marconi equipment is left with Arqiva, but when it was the BBC the local MF sites used more than a few Eddystone / Marconi 1kW modular transmitters.

There are two UK HF sites (non-broadcast) that I know of which have several Marconi HF transmitters -but that's all I can say about that.

Skelton still has six B6126 HF transmitters, but they've been off-air since 31 March 2013. I remember Tudor Pike, amongst others, coming to Skelton to give us a week's course on them as four of them were being commissioned. We got everyone else's cast-offs! Two ex-Daventry B6126s followed after these first four.

Back in '84 we got Rampisham's four redundant BD272s and another BD272 from Daventry about 1988. Interestingly, we also acquired the RF section of a Marconi BD272 from the atomic resarch establishment at Harwell, for spares! We got a salvage gang up to go down south on a raiding party.

They're long gone now.

If I hear of any more Marconi equipment in service I'll let you know.
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Old 25th Aug 2017, 9:34 am   #32
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Default Re: Rampisham: All Gone bar One...

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'...but when it was the BBC the local MF sites used more than a few Eddystone / Marconi 1kW modular transmitters.'
These were the Eddystone (a member of Marconi Communications Systems Ltd) B6038E 1kW sets.
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Old 25th Aug 2017, 1:42 pm   #33
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Default Re: Rampisham: All Gone bar One...

Ah yes, it was Tudor Pike who demonstrated the B6128 on my visit to Marconi at New Street. I remember that its 3 phase 11kV electricity supply was connected via three lengths of approx 2" copper pipe that he said they had scrounged from maintenance, supported on insulators. Much more cost-effective that buying a short length of 11kV cable! Also the massive water-cooled transmitter valve, and what seemed like miles of fibre optic cables providing the control signals to the individual 700V units of the modulator.
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Old 25th Aug 2017, 7:03 pm   #34
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Default Re: Rampisham: All Gone bar One...

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'I remember that its 3 phase 11kV electricity supply was connected via three lengths of approx 2" copper pipe that he said they had scrounged from maintenance, supported on insulators.'
That's how it was at Skelton 'C' with the B6126 transmitters: water-pipe and stand-offs. The pic shows it mounted on the wall. 11kV into the primary of the HV transformer (out of shot), then two secondaries rectified giving 26kV d.c. to the anode of the series PWM modulator valve, via the choke (rear, right), the cleardown vacuum switch and ignitron 'crowbar' protector unit (lower centre) hung across the HT rail, the capacitor inrush resistor mats (upper centre) and the HT reservoir caps (lower right).

The other pipes lead to the earthing switch-blades, manually operated before entering the smoothing enclosure, applied across HV transformer secondaries and the d.c. rail.

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'Also the massive water-cooled transmitter valve, and what seemed like miles of fibre optic cables providing the control signals to the individual 700V units of the modulator.'
The fibre optic cables over which the 60kHz clock frequency, the PWM signal and the revertive switching logic status is sent is really nothing more exciting than those little plastic light-pipes you find in Dinky toy cars to work the headlights. It can be terminated with a simple ferrule and application of crocus paper.

We've had some fun with those in the past!
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Old 25th Aug 2017, 7:39 pm   #35
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Default Re: Rampisham: All Gone bar One...

Thanks for the update Russell - I knew that you would know where things stood with the Marconi units!

I was with TV TX (solid state drive) at Marconi and that's all long gone with the advent of digital TV. The 'big stuff' was up at Building 46 at New Street (demolished years ago) and it always fascinated me. Stories about how far off the ground the enormous smoothing choke could lift itself if its stored energy was converted into potential energy always impressed me. Then there was the foot long arc one morning when a rectifier on a 1MW rig failed its overnight test. The whole lab was lit up blue along with a horrible burning smell. Manual shut-down was pretty prompt but it had been arcing for quite a while without blowing any fuses or breakers so there was quite a lot of damage. I went back to my boring RF power transistors thinking that they weren't anything like as exciting!

As an aside, and a little OT, I wonder what the oldest bit of Marconi kit still in regular professional use is? I'm not thinking of preserved kit as I do these days, but 'real' use such as an antenna or RF power amplifier.

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Old 26th Aug 2017, 8:04 am   #36
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Default Re: Rampisham: All Gone bar One...

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As an aside, and a little OT, I wonder what the oldest bit of Marconi kit still in regular professional use is? I'm not thinking of preserved kit as I do these days, but 'real' use such as an antenna or RF power amplifier.
I would think the two remaining 250kW Marconi BD272s at Woofferton would be a good contender, having come into service in 1963. Maybe the BD272 runnng 4MHz at Kranji in Singaore too (Far-Eastern Relay Station). Fifty-four years' service isn't bad!
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Old 26th Aug 2017, 11:22 pm   #37
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Default Re: Rampisham: All Gone bar One...

Out of interest I did a Google search for Marconi B6128. It yielded a BBC article which includes a photo of a fire-damaged unit of a Continental modulator, along with some comments of Marconi's use of a battered AVO and a brand-new Fluke DVM for fault-finding. Given the potential for destruction due to the high voltages, they didn't bother to waste money by having the Fluke calibrated!

http://www.bbceng.info/Technical%20R...l_Issue_42.pdf
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