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Old 6th Apr 2018, 3:42 pm   #1
Al (astral highway)
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Default GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

Periodic discussions here about pantry transmitter antenna efficiency have prompted me to post this discovery about a WW2 German system for communicating with U-boats. The skin depth at this frequency is 8-25 metres, enabling transmission through sea-water.

To quote directly:
The Kriegsmarine used the Hell-system with an LF/VLF transmitter that was absolutely gigantic, both in terms of size of the antenna system and output power. It was appropriately named Goliath, and was used for world-wide broadcast to (submerged) submarines. ...it was by far (!) the most powerful vacuum tube transmitter with tunable frequency: up to 1 Megawatt at 15-60 kHz.
The article discusses at some length the ingenious antenna array, which had a very high Q (thus making it not ideal for voice) but at this frequency, an efficiency of around 1 percent. Telegraphy including ENIGMA encryted messages.


https://www.nonstopsystems.com/radio...rx.htm#goliath

Thought this might be of interest to quite a few!


Mods, sorry, I posted a line too far down - this should of course be in Military etc.
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Old 7th Apr 2018, 10:19 am   #2
Kevin Hoyland
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

Thanks for the link AL, Telefunken were at the front of German radios for a long time.
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Old 7th Apr 2018, 5:09 pm   #3
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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Thanks for the link AL, Telefunken were at the front of German radios for a long time.
Hey Kevin,

Yes, and the company still exists - that's for well over 100 years now - currently as a high-end audio producer. It's interesting to compare the longevity of such a company with our own industrial history,

I can't bring to mind a single, large, high-end British producer of tech like this, with such a long history.
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Old 7th Apr 2018, 7:21 pm   #4
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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I can't bring to mind a single, large, high-end British producer of tech like this, with such a long history.
Marconi's Wireless and Telegraph Company?
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Old 7th Apr 2018, 7:27 pm   #5
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

It was unfortunate that the transmitter division of Marconi only just made it to Marconi's centenary year before it was closed.
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Old 7th Apr 2018, 7:59 pm   #6
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

It was indeed... But pleasing to see that fifty-five year-old Marconi 250kW HF transmitters are still broadcasting from the UK. And from abroad!

In '84 four AEG-Telefunken S4005 500kW sets and four Marconi B6127 500kW sets were installed at Rampisham. The Marconi sets had three volumes of handbooks; the AEGs had thirteen - though only one bore mucky fingerprints!

It was interesting to observe the different methods of tuning. The Marconis would put set inductor values on and tune the capacitors, whilst the AEG Telefunkens would put set capacitor values on and tune the inductor: a huge coil with two pinch-rollers that motored round it, and through which passed the HT cable.

I'm told that the Germans would not let the Marconi installers anywhere near the AEG transmitters when they were under construction!
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Old 7th Apr 2018, 9:29 pm   #7
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

I worked on a Marconi VLF transmitter in the 80s, it was used for submerged submarine comms.
I don’t remember much about it or the model number but there was a 618 foot mast which on top of the cliff was quite impressive. We used to go out at night with fluorescent tubes which would light up.

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Old 9th Apr 2018, 9:27 am   #8
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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It was indeed... But pleasing to see that fifty-five year-old Marconi 250kW HF transmitters are still broadcasting from the UK. And from abroad!

....
I'm told that the Germans would not let the Marconi installers anywhere near the AEG transmitters when they were under construction!

That's indeed pleasing! And fascinating to compare the two tuning methods.

13 volumes is quite a bit of study!
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Old 9th Apr 2018, 3:27 pm   #9
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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That's indeed pleasing! And fascinating to compare the two tuning methods.
Having variable inductors was meant to save wear on the variable vacuum capacitors, apparently. We replaced quite a few vac-caps (water-cooled) on Marconi transmitters over the years. Easy enough to replace, but expensive. And, of course, the transmission had sometimes to be covered elsewhere to do so.

I'm told that towards the end, the big final inductor coils on the AEGs ended up with 'flat-spots' on them because the same load and the same frequencies used put them at the same positions, and arcing and burning would occur. The RIZ Croatian DRM / PWM transmitters used at Skelton (at one time) and at Woofferton also use variable inductors with roller contacts, but smaller.

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13 volumes is quite a bit of study!
They were very thorough, but fault-finding was pretty-much one volume. Both Marconi and AEG manuals were extremely well-written and thoroughly comprehensive. If I have any criticism of Marconi manuals, it's that the cct diagrams were occasionally 'a touch generic' with the same drawings applying to different variants showing components that were not used on our particular senders.

I don't remember much about the AEG manuals other than that it helped if a German / English technical dictionary was to hand: it was. The AEG senders came with a slide-in card on the front panel translating the hieroglyphics beneath the controls to meaningful language.
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Old 10th Apr 2018, 4:18 pm   #10
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

I was lucky enough to be put on the first S4005 training course at Rampisham in 1983. The senior AEG installation engineer was our instructor; he had an excellent command of English and I recall we were all very impressed by the sender's HT supply protection circuit which involved a current transformer formed around the earth return conductor ("Kraemer-Wandler transformer" comes to mind); this was designed to detect any fast-rising current transient (flash-over etc.) and fire a crowbar circuit that dumped all the reservoir capacitor system energy (& tripped the Jennings vacuum switches to the rectifier bank) before it could do damage. The speed of this system was so fast that the standard test involved the deliberate application of a short-circuit formed from a 30mm length of single-strand fusewire (sorry, I can't remember the rating but it was well below the potential fault current). The system passed the test if the fusewire stayed intact ... !

Cheers
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Old 10th Apr 2018, 9:44 pm   #11
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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The speed of this system was so fast that the standard test involved the deliberate application of a short-circuit formed from a 30mm length of single-strand fusewire (sorry, I can't remember the rating but it was well below the potential fault current). The system passed the test if the fusewire stayed intact ... !
Same on the Marconi senders, Guy, and, funnily enough, the ignitron pulse unit circuit diagram was one that was 'mis-represented' in the diagrams.

Those crowbar tests were always fun if the ignitron didn't fire! 9464 Joules is a lot of energy to be dissipated in the aforementioned wire.
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Old 11th Apr 2018, 1:15 pm   #12
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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Those crowbar tests were always fun if the ignitron didn't fire! 9464 Joules is a lot of energy to be dissipated in the aforementioned wire.
Whaaaaaaaat!

Did you have ear-defenders? That's like a figure you'd get in ballistics!
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Old 11th Apr 2018, 2:18 pm   #13
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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9464 Joules is a lot of energy to be dissipated in the aforementioned wire.
How long did the timewarp protal open for?
Any photographic film nearby might have captured evidence of the Higg's boson as well.

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Old 11th Apr 2018, 5:19 pm   #14
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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How long did the timewarp protal open for?
Any photographic film nearby might have captured evidence of the Higg's boson as well.
That's definitely silly enough GigaWatts needed to blow to pieces Back to the Future's 'Flux Capacitor!'
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Old 11th Apr 2018, 6:53 pm   #15
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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Did you have ear-defenders? That's like a figure you'd get in ballistics!
It did make rather a pop and a splash, yes. Or could do if one had left the ignitron trigger wire off after maintenance (say). But as Guy says, the rapidity of the ignitron cutting in following overload sensing through the C/T (one of three on the Marconi B6126) and discharging the Ten 2.8uF reservoir caps in parallel sitting at 26kV d.c. usually worked a treat with sometimes a mere browning of the test wire.


The attached pic shows the Marconi arrangement. Don't think I've an AEG-Telefunken pic. The ignitron fast-trip crowbar protection was a presequisite of maintaining the valve warranty. Thales used to manufacture ignitrons at their factory in Thonon, on Lake Geneva.

There was much mention of Higgs-Boson and Jigawatts (or words to that effect... ) if things went off bang!

We did have ear-defenders.
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Old 11th Apr 2018, 7:15 pm   #16
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

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Quote:
Originally Posted by russell_w_b View Post

Those crowbar tests were always fun if the ignitron didn't fire! 9464 Joules is a lot of energy to be dissipated in the aforementioned wire.
Whaaaaaaaat!

Did you have ear-defenders? That's like a figure you'd get in ballistics!
The standing rule where I used to work was that ear defenders were mandatory PPE for any test/development activity involving more than 1kJ of stored electrical energy. The bang volume was very dependent, however, on whether the arc was in gas or in liquid/solid (quieter in gas) and whether there was any significant resistive current limiting (quieter if there was). Our large pulser stored up to 160kJ at full charge. And I was once present when it 'let go' unexpectedly into a water arc at that energy.

Cheers,

GJ
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Old 12th Apr 2018, 1:26 am   #17
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

What is the square component in the center of the photo. The one with a woven appearance?
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Old 12th Apr 2018, 9:28 am   #18
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Default Re: GOLIATH - monster Telefunken WW2 transmitter at VLF (16-20KHz)

Parallelled resistive mats for the ignitron to discharge the capacitor bank into?

That room gives the impression of being somewhere where you'd want to be really, really sure that your shoelaces were properly done up....
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Old 12th Apr 2018, 10:34 am   #19
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Parallelled resistive mats for the ignitron to discharge the capacitor bank into?
Partly, yes. They were inrush current resistors but were in series with the capacitor bank. Kevlar mat resistors. The ones at Skelton 'A' used to be asbestos! After the initial brunt of the discharge, and as part of the sender 'HT Off' procedure, the four HT vacuum switches feeding the rectifier frame would open and a 'cleardown' vacuum switch would close, discharging the HT rail into a stack of ten 'Polo-mint' silicon resistors (something like four inches in diameter?) of a total value of 330 Ohm.

On occasion, the ashlam rod upon which the resistors sat went up like a Roman candle!

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That room gives the impression of being somewhere where you'd want to be really, really sure that your shoelaces were properly done up....
It was an interlocked room and you'll notice the earth wand on the capacitors as a 'belt-and-braces' precaution. Before access was allowed and a key withdrawn, the earth switch was applied and could be seen through a window making contact with the a.c. side of the rectifier frame and the reservoir capacitors, as well as the output of the PWM switching valve and its filter cct. So bad things didn't happen.

Phew!
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