WW2 use of low frequency transmitter

[jimscoper]

Been looking at German radio in early WW2 and I am a bit curious as to their use of transmitters and receivers in the 100KHz to 1.2MHz region. The Langwellen Sender 100/08 is an example.

Very well made etc but slap bang in the middle of broadcast bands when I would have expected them to use bands in the 4 to 9MHz region.

Why do this and did this actually work and did it die out early on or continue?

[Radio Wrangler]

Navigational beacons work well in that part of the spectrum, using groundwave propagation. In fact quite a few are still there.

David

[M0FYA Andy]

What frequencies did U-boat communications use?

Andy

HF, hence the Huff Duff direction finder https://en.wikipedia.org/wiki/High-f...ection_finding

[FrankB]

Most of the WW2 historical books I read mentioned the LF use of radio for U boat communications.
I know the U.S. uses- or did anyway- VLF for sub communications. You didn't need to surface to receive messages.
I -think- I read where some underseas beacons also use that frequency. Possibly for Tsunami warning system? or intruder detection).

The U.S. has a license free band on 180KC for experimentation and beacons. 1 watt max, and, IIRC, no more than 50' antenna, including lead in. ( See book: VLF Handbook for details, and a late '60s Popular Electronics had an article for a transmitter using a 12AX7 tube. Built one of those & it worked OK).

[Restoration73]

I have also built the "Transmitter for the Neglected band" I used a EL84(6BQ5) in place
of the 6AQ5. My version has a vfo coverage of 130-570 kHz which permits use as LW
(and low MW) pantry transmitter, and also UK ham use on 136kHz and 475kHz bands.
There is an actual vintage transceiver in the link;
http://www.auroralchorus.com/pli/pli.htm

[russell_w_b]

Originally Posted by M0FYA Andy

What frequencies did U-boat communications use?

VLF after 1943, using the 'Goliath' system. 15kHz - 25kHz. Can't penetrate seawater with much else!

[m0cemdave]

You may have found this site already but if not, it may be helpful:

https://www.cdvandt.org/

including:

https://www.cdvandt.org/goliath.htm

There's a searchable index here (download the pdf and use control-F with key words to find which sections to look at):

https://www.cdvandt.org/subject_ref_dbase.htm

HTH

[M0SOE_Bruce]

It wasn't just the Germans. The UK developed the wireless set 14 in 1940 for armoured vehicles. It tuned 290-410 KHz.

[G6ONEDave]

I have a Marconi TF1331 oscilloscope, which I was told was used for looking at these VLF signals. The scope has positions 1, 3, 10 seconds on the timebase selector switch. It also has 1, 3, 10, 30, 100 and 300 msecs as well as 1, 3, 10, 30, 100 and 300 usecs. The scope seldom gets any use these days and would probably need a full service / restoration before it could be put back into service again.

[jimscoper]

Thanks very much everyone. M0cemdave, I now know how to pass a dull wet afternoon - very interesting. I knew about VLF but it was going across the old Long and Medium Wave bands that surprised me.

The past is a different country.

[G3VKM_Roger]

Originally Posted by jimscoper

Thanks very much everyone. M0cemdave, I now know how to pass a dull wet afternoon - very interesting. I knew about VLF but it was going across the old Long and Medium Wave bands that surprised me.

The past is a different country.

I have HRO and HRO-50 receiver coil packs for 50 to 100 kHz but haven't heard anything identifiable. Anyone know if there is any activity in that band?

"The past is a foreign country: they do things differently there". One of my favourite opening lines, comes from the book "The Go-Between".

73

Roger/G3VKM

====================================
Just because your voice reaches halfway around the world doesn't mean you are wiser than when it reached only to the end of the bar. - Edward R. Murrow

[Jon_G4MDC]

Those coil packs will mostly cover the time stations MSF , DCF77 etc.
Not much fun to listen to.

[trh01uk]

Originally Posted by jimscoper

Been looking at German radio in early WW2 and I am a bit curious as to their use of transmitters and receivers in the 100KHz to 1.2MHz region. The Langwellen Sender 100/08 is an example.

Very well made etc but slap bang in the middle of broadcast bands when I would have expected them to use bands in the 4 to 9MHz region.

Why do this and did this actually work and did it die out early on or continue?

Simple really. They wanted good ground wave range, and as you go down in frequency that range improves - dramatically. Radio 4 long wave of course being a good example.

The British WS18 started life as a set covering 6 - 9MHz. Then came the same set but at a lower frequency of 3 to 5.2MHz (I think) - called the WS68. Then that set was reinvented as a WS68P covering 1.75 - 2.9MHz, again to get that better ground wave range.

It died out rapidly post-WWII because VHF sets came along, with FM rather than AM, and the improvement in voice quality, both from a good S/N ratio plus freedom from interference meant that ground wave on HF was really on its way out. Apparently the Americans turning up at D-Day with their BC-1000 sets (40 - 48MHz, FM) was a revelation - "this is how radios should work"!

Richard

[73TORANA!]

The LF band was used extensively by the RAAF in the pacific theatre. The Aircraft fitted with a 130 - 500Khz transmitter used a trailing antenna that had to be wound in prior to landing. The AWA AR8 AT5 LF / HF radio system designed and built here in Australia was used in Beauforts and Beaufighters in New Guinea / New Britain and coastal patrols of Australia areas for example. While the primary frequency was around 6800Khz, LF frequencies between 200 and 500 Khz were used.

Geoff.

[majoconz]

My best catch has been Palmerston North from Alice Springs 4293km 335kHz but heard only once - I keep trying! Often get Port McQuarie PMQ on 395kHz but I think he's gone QRT too - probably replaced with a VOR/DME. That was when I lived on top of a nice hill overlooking the town - unfortunately now I'm down in a valley!

[73TORANA!]

Unfortunately most NDB's have gone now here in Aus but I found mid winter is the best time.
Cheers Geoff