# Spurious and curious



## Wismajorvik (Dec 29, 2011)

1. In the early sixties while watching BBC, (low band channel 2) I observed horizontal "bars" appearing across the screen. I recognised that it was actually morse code, SVA constantly repeated. Eventually the ship made contact with Athens and passed his message, from that I obtained the ship's name. A quick check of the local 'paper indicated the ship was in dock, about three miles away.
2. Off Port Said waiting for the convoy to assemble I experienced loud key clicks over the rx, (500Khz). I tuned up to 4Mhz to find a strong signal, the vessel was calling GKS, ie Portishead 16Mhz not GKH 4Mhz. I recognised the call sign as the 'Canberra'. Obviously I was receiving the transmitters oscillator frequency and a quick trip to the bridge identified that ship a couple of miles away.
An interlude in the boring watch keeping endured while waiting for and transiting the canal.


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## Searcher2004 (May 3, 2012)

Wismajorvik said:


> 1. In the early sixties while watching BBC, (low band channel 2) I observed horizontal "bars" appearing across the screen. I recognised that it was actually morse code, SVA constantly repeated. Eventually the ship made contact with Athens and passed his message, from that I obtained the ship's name. A quick check of the local 'paper indicated the ship was in dock, about three miles away.
> 2. Off Port Said waiting for the convoy to assemble I experienced loud key clicks over the rx, (500Khz). I tuned up to 4Mhz to find a strong signal, the vessel was calling GKS, ie Portishead 16Mhz not GKH 4Mhz. I recognised the call sign as the 'Canberra'. Obviously I was receiving the transmitters oscillator frequency and a quick trip to the bridge identified that ship a couple of miles away.
> An interlude in the boring watch keeping endured while waiting for and transiting the canal.


Another example of RF breakthrough is the 16kHz signal from Rugby/GBR which was accidentally superimposed onto Mike Oldfield's "Tubular Bells".

See:- http://www.youtube.com/watch?v=PQaBF9_9C8I


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## Wismajorvik (Dec 29, 2011)

I once heard superimposed over the BBC World Service a w/t transmission to a British High Commission but I guess that was due to landline problems at Crowborough!


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## david.hopcroft (Jun 29, 2005)

At GKZ, we once heard a police chase commentary coming out of our VHF Ch16 speaker for Grimsby Radio/2GY. I reported it and they seemed unconcerned - don't think it was understood !!. It must have been close to the site of 2GY on the Telephone Exchange in Grimsby. One of our aerial boffins said 'what do you expect using a bent coat hanger for an aerial on an unmarked banger' !!

David
+


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## Basil (Feb 4, 2006)

Recollect, years ago, mentioning to the Beeb that there seemed to be an Egyptian Orchestra accompanying some of their (IIRC) MF transmissions. "Ah, yes, the ubiquitous Egyptian Orchestra." came the reply. I guess some transmitters had harmonic/sideband problems. (Sorry if I'm using the wrong terms - Bas, 'Steam turbine driver'  )

ps As teenager, did build little valve superhet, which was when I realised how the bad guys in WW2 could tell who you were listening to. Up till then I'd thought; 'If yer only receiving, how do they know?'


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## Searcher2004 (May 3, 2012)

Basil said:


> Recollect, years ago, mentioning to the Beeb that there seemed to be an Egyptian Orchestra accompanying some of their (IIRC) MF transmissions. "Ah, yes, the ubiquitous Egyptian Orchestra." came the reply. I guess some transmitters had harmonic/sideband problems. (Sorry if I'm using the wrong terms - Bas, 'Steam turbine driver'  )
> 
> ps As teenager, did build little valve superhet, which was when I realised how the bad guys in WW2 could tell who you were listening to. Up till then I'd thought; 'If yer only receiving, how do they know?'


There was a lot of concern, on both sides, during WW2 about radiation from superhet local oscillator signals and quite a few military "straight" (TRF) radio receivers were built to overcome this problem. 

If you read "Spycatcher", there's reference to Operation "Rafter" which was a project to have aircraft criss-cross London at night listening for Soviet spies who were using mobile short-wave receivers to receive instructions from abroad. 

See (amongst others)-

http://www2.warwick.ac.uk/fac/soc/pais/people/aldrich/vigilant/lectures/gchq/rafter/

Cheers,

Searcher


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## Wismajorvik (Dec 29, 2011)

Searcher2004 said:


> There was a lot of concern, on both sides, during WW2 about radiation from superhet local oscillator signals and quite a few military "straight" (TRF) radio receivers were built to overcome this problem.
> 
> If you read "Spycatcher", there's reference to Operation "Rafter" which was a project to have aircraft criss-cross London at night listening for Soviet spies who were using mobile short-wave receivers to receive instructions from abroad.
> 
> ...


I remember reading that a distant RN ship had tracked a WW2 convoy by using DF receiving the radiation from the reaction control of TRF receivers. In the 60s I had a Mackay Marine station on board, the main RX a TRF and I could activate the auto alarm by "over reacting" at four second intervals. (I did find the job boring most of the time!)


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## Varley (Oct 1, 2006)

Basil said:


> Recollect, years ago, mentioning to the Beeb that there seemed to be an Egyptian Orchestra accompanying some of their (IIRC) MF transmissions. "Ah, yes, the ubiquitous Egyptian Orchestra." came the reply. I guess some transmitters had harmonic/sideband problems. (Sorry if I'm using the wrong terms - Bas, 'Steam turbine driver'  )
> 
> ps As teenager, did build little valve superhet, which was when I realised how the bad guys in WW2 could tell who you were listening to. Up till then I'd thought; 'If yer only receiving, how do they know?'


Sounds as if your LO was a bit on the powerful side. I'm reminded, radar klystrons almost never failed because of weak output only due to loss of stability - LO strength is of little importance compared with the wanted signal which will always be weaker.


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## sparks69 (Dec 18, 2005)

I can remember sailing up the Bristol Channel and getting QRM from some Swiss VHF station talking to river barges. The O/M told me it was all due to the Nuke Power station we were passing at the time !
Happy Daze !


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## Moulder (Aug 19, 2006)

sparks69 said:


> I can remember sailing up the Bristol Channel and getting QRM from some Swiss VHF station talking to river barges. The O/M told me it was all due to the Nuke Power station we were passing at the time !
> Happy Daze !


Ah bless 'im.

(Thumb)


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## Naytikos (Oct 20, 2008)

There used to be a problem with 'Medium Wave' broadcast reception over much of central southern England due to interference from GNI. Niton's working frequency, as everyone will remember was 464Kc/s and domestic radio receivers always used an IF of 465Kc/s. 

I seem to remember that, for a while at least, some manufacturers actually produced receivers using a different IF and marketed them solely in the affected area. 

I wouldn't be surprised if there are statistics showing that listeners in that area adopted the FM VHF broadcasts sooner than the national average.


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## Worldspan (Jan 2, 2012)

Yes, IF breakthrough was a problem at both Eastbourne and Hastings.
W


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## LouisB (Dec 23, 2007)

Many,many moons ago I had a rented flat in Liverpool. New tenants moved into the flat above me and within a day or so life became miserable due to loud music being played day and night on their new 'music centre' FM radio (remember them?). Despite complaints nothing happened and so, using a simple circuit, from I think, Practical Wireless, I constructed a fairly unstable 10.7 MHz oscillator. The output, which must have been only a few milliwatts, was sufficient to swamp the offending radio's i.f. and give me a nights rest. They took their music centre back to the shop as faulty and I moved on.

LouisB. (Scribe)


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## trotterdotpom (Apr 29, 2005)

sparks69 said:


> I can remember sailing up the Bristol Channel and getting QRM from some Swiss VHF station talking to river barges. The O/M told me it was all due to the Nuke Power station we were passing at the time !
> Happy Daze !


..... and who were you to argue with a superior intellect?

John T


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