# Effects of RF on other equipment



## Peter Eccleson (Jan 16, 2006)

Anyone ever experience any interesting effects on other equipment when transmitting?

I did the builders sea trials on Rowbothams 'Tankerman' out of Appledore shipyard in the 80's. We were on the first run on the 'measured mile' and she suddenly went hard to starboard, unexplained but she was on autopilot at the time. 
Other things happened - unexplained engine room alarms etc. we did lots of investigation and tried to replicate events of that afternoon. 

Finally got it down to me testing the new Sailor main station on 8Mhz key-down! Wow ....... off she went hard a starb'd again. Found some of the routing of main cabling down to the engine room was run over the top of the radio room. Lots of activity re-routing cables after that.


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## tunatownshipwreck (Nov 9, 2005)

Good thing it was discovered then and not in some crowded area.


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## sven-olof (Jul 12, 2008)

Interesting with examples on EMC. Electrical magnetic compability.
Thats why cell- Phones should be forbidden in hospital areas with medical equipment.


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## Varley (Oct 1, 2006)

Lots of nice straight edges to waveforms with TOR seemed to be the most usual cause of EMI but we did do some trials with hand-helds and GSM as well (following report of pagers tripping ferry diesel generator via the OMD). I think it was Broompark where the telegraph reply 'needle' was seen to 'respond' when walkie-talkie transmitting nearby.

Not so much important that it happens just that you know that it happens.


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## Leratty (Jun 3, 2012)

sven-olof, I thought they were certainly there are signs all of the wards etc in Aus, Hong Kong & here in France? Always amazed me that you are supposed to shut them down in petrol stations yet you see everyone yabbering away as they fill up?


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## howardang (Aug 3, 2008)

Peter Eccleson said:


> Anyone ever experience any interesting effects on other equipment when transmitting?
> 
> I did the builders sea trials on Rowbothams 'Tankerman' out of Appledore shipyard in the 80's. We were on the first run on the 'measured mile' and she suddenly went hard to starboard, unexplained but she was on autopilot at the time.
> Other things happened - unexplained engine room alarms etc. we did lots of investigation and tried to replicate events of that afternoon.
> ...


After builders trials and so on I took delivery of a brand new supply vessel, Fastnet Shore, at Appledore for the initial run to Aberdeen to start a charter for Shell. After a trouble-free run around the coast and before entering Aberdeen I stopped in the bay and had a play to make sure all was still OK. After the checks for some reason I rang the Engine Room on the hand cranked emergency telephone and as the Chief answered I could hear both main engines shutting down with the appropriate alarms. After a couple of repeats we realised that the telephone was causing the main engine emergency shut down to trip. It could have been a tad embarrassing if it had happened when in the close confines of Aberdeen Harbour!

Howard


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## LouisB (Dec 23, 2007)

Peter Eccleson said:


> Anyone ever experience any interesting effects on other equipment when transmitting?
> 
> I did the builders sea trials on Rowbothams 'Tankerman' out of Appledore shipyard in the 80's. We were on the first run on the 'measured mile' and she suddenly went hard to starboard, unexplained but she was on autopilot at the time.
> Other things happened - unexplained engine room alarms etc. we did lots of investigation and tried to replicate events of that afternoon.
> ...


Also the same on an RFA I was on. Can't remember if it was also 8 MHz or possibly 12 that caused the helm to go hard over. Another thing was long runs of cables that although disconnected had enough voltage to give a shock - later found that on the overall routing of the cable it had a couple of turns around 440 volt supply cables on the main cable tray. Replaced with screened cables earthed at both ends.

LouisB. (Scribe)


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## sven-olof (Jul 12, 2008)

There is a great problem with cellphones as They are normal part of peoples Held tools and hospital standards only call for a compability in the equipment with 3 or 1 volt per meter field strength.


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## Ron Stringer (Mar 15, 2005)

Peter Eccleson said:


> I did the builders sea trials on Rowbothams 'Tankerman' out of Appledore shipyard in the 80's. We were on the first run on the 'measured mile' and she suddenly went hard to starboard, unexplained but she was on autopilot at the time.


On Friday, at the monthly MIMCo Chelmsford 'Lunch', a long-time-no-see former colleague Keith Rundle dropped in. He was telling us about doing sea trials in Japan aboard the new Shell tanker _'Mytilus'_, where they had the same problem when he went on to 22 MHz on the _Conqueror_ transmitter. A 280,000 dwt tanker going hard a-starboard at full speed must have set a few sphincters a-twitch!

There were lots of similar occurrences aboard a wide range of ships during the 1960s and '70s, when the basic conventional new ship-fit switched, from using 100W transmitters, to 1,500W and above. And as David Varley says, the introduction of TOR and DSC in the 1970/'80s brought a further rash of problems. It took some radio installers a long time to appreciate the need for improved earthing methods for the higher-power transmitters, and even longer for most shipyards and other equipment suppliers to appreciate the importance of screening and care when arranging cable runs. 

There were ships where lifts stopped, where alarm systems were set off and where engines, generators or other items of engine room equipment were shut down whenever the transmitter started up on certain frequencies.

There are some odd co-incidences come up on this site. On another thread there are postings about tanker explosions during tank cleaning, including several involving Shell 'M'-class tankers. Keith Rundle (see above) was also telling us about his ship _'Mytilus'_, arriving on scene following the tank-cleaning explosion aboard the Dutch-flag Shell tanker _'Marpessa'_. He also confirmed that the two Radio Officers aboard another sister-ship _'Mactra'_, (which survived a similar explosion), were employed by IMR, a question that was posed on that thread. 

I hadn't seen Keith for some 40-odd years and yet he raised two subjects being discussed on SN in the days previous to our latest meeting!


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## 5TT (May 3, 2008)

I joined my very last ship in Durban and found the gear in a sorry state. The auto key wasn't working at all, the cams were all loose, almost as if it had been sabotaged, the R408 wouldn't calibrate on most bands, and the ST-1400 was only able to deliver less than a quarter of it's rated power with the drive wound right up.

Fortunately I had some time before we sailed to sort this lot out but there wasn't much to it, the auto keyer was just a matter of lining the cams up and tightening a few screws, I always carried a Thandar portable frequency counter with me so an hour or two on the R408 and that was all fine, and the ST-1400 presented an I/F amplifier valve anode glowing bright orange when I pulled the drawer out, and replacing a short circuit cathode bypass capacitor sorted that out.

First QTC on sailing from Durban was to Tokyo, 12mhz in the evening was always easy and I had no problem, however although I noticed the cathode current flicker a bit while tuning up there were no accompanying noises and nothing smelt funny so I carried on and cleared the traffic. Next morning I'm asked to accompany the old man up onto the monkey island to explain the steel bolts rolling backwards and forwards as the ship gently rolled, and the various small bits of charred wood laying around, and I couldn't help noticing out the corner of my eye that the wooden cage around the Dieckmann & Klapper main antenna was completely gone. I've no idea why they had elected to replace the original cage with this thing but they had built it on the previous trip, while the transmitter was running at a fraction of its rated power. Anyway that wasn't all, later that day I tested the newly installed 
2182khz watch keeping receiver and, while it was still receiving okay it failed to respond to the two-tone test signal. A quick scout around with the logic probe revealed some faulty 4000 series chips, no spares, so I got the old man to radio ahead for these and in fact ended up in a car with the ships agent in Japan to buy them over the counter some place. Replaced them and away it went again, no problem, checked it the next day while still alongside, still fine, but it failed again when we got back out to sea, ie after I'd used the main tx again, same faulty chips.

Safmarine operated a company schedule on 16mhz 2nd working frequency 3 times per day, collective callsign ZTMC and on a couple of occasions requested that other ships tune up and down the band a bit while I QSV to see if I wasn't in a few other places that I shouldn't have been but nothing ever turned up and on another occasion I went down to an 8 mhz frequency while the other chap listened for the 2nd harmonic but that turned up nothing either, the rig sounded good and seemed to be working fine.
I couldn't easily see the transmitter earthing scheme because it was hidden by furniture so I burrowed through the back of a cupboard so as to get a good look with a torch and it was the standard arrangement, that thick copper sheeting bolted to the bulkhead, couldn't see anything I could do there, so I logged the problem in the maintenance report and handed it over to the next guy when I signed off in Durban.

Having resigned shortly after that I never did get to follow up on what the problem was. The ship was only a short while away from that final trip to the breakers so it's quite possible it was never resolved.

= Adrian +


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## Paul Braxton (Jul 21, 2005)

Hi Ron.

Interesting about the Shell 'M' Class tank cleaning explosions in the early '70's, and in particular the Dutch Shell 'Marpessa'. I was onboard Shell's 'Serenia' at the scene (off Dakar) in late '69, and we stood by the crippled and sinking ship for some three days until she finally slipped under. Don't recall ever realising 'Mytilus' was anywhere near! 

Would be interesting to hear Keith Rundle's tale of that event.

Regards, Paul


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## Ron Stringer (Mar 15, 2005)

Paul Braxton said:


> Hi Ron.
> 
> Interesting about the Shell 'M' Class tank cleaning explosions in the early '70's, and in particular the Dutch Shell 'Marpessa'. I was onboard Shell's 'Serenia' at the scene (off Dakar) in late '69, and we stood by the crippled and sinking ship for some three days until she finally slipped under. Don't recall ever realising 'Mytilus' was anywhere near!
> 
> ...


Paul,

Yesterday when I looked up the reports of the incident I noticed that Serenia was given as the first ship on scene, so I too had my doubts about the story! But as Keith lives somewhere in Salisbury and rarely visits Chelmsford (I think he was on the way home from a trip up North), it may be another 40 years before I speak to him again.


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## King Ratt (Aug 23, 2005)

RFA Regent had been fitted with a new type of Rasrig ( Louis B, was it nicknamed Snoopy?). It had a distinct dislike of FSK transmissions in the 4 Mhz band. Lots of rewiring and shielded cabling was involved in solving the problem.


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## LouisB (Dec 23, 2007)

King Ratt said:


> RFA Regent had been fitted with a new type of Rasrig ( Louis B, was it nicknamed Snoopy?). It had a distinct dislike of FSK transmissions in the 4 Mhz band. Lots of rewiring and shielded cabling was involved in solving the problem.


@KR

Yes Rab also with fsk type transmission - On the Resource the helm control cables being swamped by (badly tuned  tx output from what I remember. There was a vertical tx antenna with a base atu that was later found to have seawater inside. The ship itself with having such large unbroken main cable runs were also susceptible to inducing voltages into nearby control/low voltage cables. Rapidly followed by installing shielded cables and thick braided copper earthing tapes. I could always tell when transmission was happening as my neon test screwdriver used to light up whenever I was on deck.

LouisB.


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## M29 (Apr 20, 2007)

Hi All
I was R/O on maiden voyage of one of Mr Bibby's ships. We had a random occurance of the main engine suddenly coming from full away down to slow ahead, which caused quiten a pandomoniium as you can imagine. The engine was switched to manual and the revs gently raised to full away. It was then switched back to bridge control and nothing would go wrong for a couple of days, when it would happen again.
It was I who made the connection, it always happend when I was on watch and particularly when transmitting on 8 MHz, a band I never used except for AMVERS to USCG.
I told the C/E of my conclusions and he thought I was talking rubbish, so I told him I would stop the main engine on Sunday morning when he was having his regular beer with the OM.
Sure enough, Sunday morning, key down 8MHz and the engine dropped to slow ahead!
We solved the problem by adding extra earthing to the bridge engine control electonics.
After that, the company insisted that during trials of a new ship, the R/O had to try every band and frequency to ensure no adverse effects on any of the ships other systems.

Best Wishes

Alan


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## Ron Stringer (Mar 15, 2005)

M29 said:


> Hi All
> I was R/O on maiden voyage of one of Mr Bibby's ships. We had a random occurance of the main engine suddenly coming from full away down to slow ahead, which caused quiten a pandomoniium as you can imagine.


On the maiden voyage of the _Regent Pembroke_, a 63,00 dwt steam-turbine tanker with bridge control, whilst on passage through the Eastern Mediterranean to Port Said she twice went from full ahead to full astern. Fortunately for me (the R/O) both times it happened in the middle of the night when I was asleep in bed (and the _Globespan_ transmitter was switched off). It certainly got people up and awake pretty quickly, as the vibration was something to be experienced - even up in the midships accommodation. Down aft it must have been horrendous.

The fault was somewhere within the engine room electronics which were unable to cope with the higher temperatures in warmer climes. Great anxiety when passing through the Suez Canal but the fault didn't recur until we were well down the Red Sea. All sorts of bits and pieces were replaced in Ras Tanura and one or more of the changes fixed the problem. There were plenty of other problems - including frequent blackouts - to keep the engineers on their toes and keep me very busy with telegrams and HF 'phone calls to the builders and their suppliers for the next 6 or 7 months.

It was about 12 months before things settled down and we got rid of the last supplier's representative but, as far as I can remember, none of the problems were caused by the radio installation. Just about every other possible cause but not EMC.


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## Peter Eccleson (Jan 16, 2006)

Ron Stringer said:


> On Friday, at the monthly MIMCo Chelmsford 'Lunch', a long-time-no-see former colleague Keith Rundle dropped in. He was telling us about doing sea trials in Japan aboard the new Shell tanker _'Mytilus'_, where they had the same problem when he went on to 22 MHz on the _Conqueror_ transmitter. A 280,000 dwt tanker going hard a-starboard at full speed must have set a few sphincters a-twitch!
> 
> There were lots of similar occurrences aboard a wide range of ships during the 1960s and '70s, when the basic conventional new ship-fit switched, from using 100W transmitters, to 1,500W and above. And as David Varley says, the introduction of TOR and DSC in the 1970/'80s brought a further rash of problems. It took some radio installers a long time to appreciate the need for improved earthing methods for the higher-power transmitters, and even longer for most shipyards and other equipment suppliers to appreciate the importance of screening and care when arranging cable runs.
> 
> ...


Hi Ron
Kieth Rundle.... he was my boss at Racal Comsec shortly after I came ashore in the early 80's. Small world. Glad to know he's still about!

Regards

PE


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## Peter Eccleson (Jan 16, 2006)

I guess induced RF meeting a diode or two ....you get a nice DC signal to whatever electronic control. Early days of engine room control systems back in the 70's and early 80's and no real comprehension of the power/proximity of some of the main transmitters being fitted at that time.


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## King Ratt (Aug 23, 2005)

Greetings again LB. Ref your #14 posting. That whip was the only antenna that the Type 640 transmitter aka Marconi NT204, could connect to. What a lot of trouble caused by a power output of 750 watts max!

Best regards

Rab T


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## sparks69 (Dec 18, 2005)

Decca Nav would always light up and the dials would spin whenever I went on 6 mHz.


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## Bill Greig (Jul 4, 2006)

A common fault on fishing boats with Sailor Radio R/T fitted was for the green Decca lane to go off by a couple of tenths. For these guys fishing close into a wreck this could prove costly with a torn net. The Sailor radio did not have to be switched on just for LW, I think to be selected on the receiver. Fix was soldering a 100uf capacitor across the selector switch contacts in the Sailor Rx.
Bill


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## M29 (Apr 20, 2007)

sparks69 said:


> Decca Nav would always light up and the dials would spin whenever I went on 6 mHz.


Hi
Interference with Decca Nav was a well known problem. On new installations we always tested the radio across all bands whilst the Decca Guy was setting up the Decca Receiver.

Alan


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## chadburn (Jun 2, 2008)

It does seem strange that lessons were not learnt bearing in mind aircraft cable was heavily shielded to prevent interference to onboard equipment during WW2. The cabling on our Motor Cruiser was all ex aircraft from scrapped aircraft. Seems to have been a cost cutting exercise by Shipbuilders.


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## david.hopcroft (Jun 29, 2005)

At GKZ, before WT there ceased, we had a whizz kid photographer with all the latest gear come to do some publicity shots. He didn't 'rate' us mere RO's much, but we soon found a way to upset him when setting up the perfect shot with his new state of the art light meter. Keyed the old W5 on WT and watch his puzzled face when it went haywire!!

David
+


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## LouisB (Dec 23, 2007)

R651400 said:


> When solid state became a reality rfi and the vulnerability of transistorised equipment to extraneous pickup was well known in amateur circles.
> Looking at the bizarre history on this thread I wonder if companies when they moved to solid state ie Decca didn't research rfi as a threat or did they?


When I came ashore I worked a few years for a company that designed and manufactured digital amplifiers and outstation safety voice systems for London underground as well as British Rail. Every system was tested for resistance to external EM interference. This was involving high strength radiation on a broad spectrum of frequencies before they were installed. Seemingly a lot of marine installations do not seem to be tested to the same standard. Apart from some military equipment I have worked with in the past, the standard of a lot of commercial kit was a bit of a lottery as to whether it would be affected or not.

LouisB. (Scribe)


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## cajef (Feb 8, 2012)

In the thirty years I worked for Decca and installed hundreds of navigators 95% of the cases involving phase shifts of the decometers or loss of lock was always caused by poor earthing.

We use to run an independent earth for the navigator and all cables used were screened and earthed, unfortunately some companies looking to earth their equipment would look and think 'Oh that is a nice copper earth strip I can just tag my gear on to it' and others thought they didn't need to use screened cable or any earthing at all.

We had loads of problems with one small independent electronics company who used to run transmitter aerials within a few inches or feet of the Decca aerial and they also thought earths were unnecessary.

The same company installed two Decca Radars interswitched on a new build, they couldn't get them to work so called us in as they thought that it would cost nothing as they were brand new and under guarantee, I found they had wired the interswitch incorrectly and the cables were too short to correct them, new cables had to be run, needless to say they were charge for the work, oh! and they had not bothered to earth any of the cable screens anywhere in the radars.


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## Ron Stringer (Mar 15, 2005)

From the early 1970s onwards, the type approval arm of the German Post Office used to test marine radio/radar equipment for EMC. As well as the measurement of unwanted and spurious radiation (ie radiation outside that permitted by the standards) from marine transmitters and receivers, they also measured the resistance of such equipment to radio interference and to transients on the electrical supply. Their EMC standards eventually became adopted and enhanced to result in today's CE standards. Of course the GPO, later the MPT, the DTI and their successor the Radiocommunications Agency had no such requirements prior to their introduction as part of European legislation.

The German engineers of their testing laboratory (FTZ in Darmstadt) were exceedingly thorough - especially when testing equipment not manufactured by a German company - but when you had satisfied their requirements, you could be confident that your equipment was fully compliant and should not cause problems aboard ship. 

Unfortunately there were no such EMC standards for ships' supplies or most other equipment on board. Even radio equipment type approved by the GPO etc., could be way outside the standards required elsewhere. So whenever there was a problem with ship-borne equipment or supplies, even though we were confident that we would be in the clear, it was almost impossible to convince the shipyard, the owners or the supplier of the equipment involved in the interference that _they _had a problem. 

EMC is a mutual problem but when only one party is constrained to meet adequate standards there is no easy solution. A little like the situation with vibration aboard ship - the radio/radar equipment had to operate to its normal performance standard whilst undergoing vibrations of 1G in all three planes at frequencies up to 50Hz. It was tested during type approval to confirm that requirement was achieved. However there was no matching standard limiting the acceleration or frequency that the ship applied to the equipment in real life operation. On some ships, vibrations well in excess of 1G were applied to radar or transmitting antenna masts at certain frequencies. When, as a consequence, the mast broke or the equipment was shaken to pieces, the equipment supplier was expected to come up with a solution.


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## Paul Braxton (Jul 21, 2005)

Hi to you, Ron.

Hope you get to talk to Keith before another 40 years is up! Crikey!

Out of interest, where did you look up details of the sinking? I had an email from a Dutch R/O a while back, telling me he was on one of the ships standing by that day and had taken lots of photo's. I saw the good old 'Serenia' in one of them that he sent me. Amazing to revisit it all again after all these intervening years.

Regards, Paul


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## chadburn (Jun 2, 2008)

There has been problems with Fylingdales and spurious emissions in the past, the old Fylingdales Golf Balls had large RADAR Scanners inside which pointed to the East and only traversed 180 deg which became weakness in the system when the Russians moved their Nuclear Missile Subs into the Atlantic. The new Fylingdales has a 360deg phased array system. This caused problems for some motorists with electronic ignition systems who had stopped nearby and could not restart their cars. The RAC, AA and a local garage had to tow the affected cars away and down into the valley where the cars were restarted without problem.


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## sparks69 (Dec 18, 2005)

If you had a Vauxhall in the 90s onwards there used to be a note in those dinky little handbooks that told you not to park near transmitting aerials.

Oh and when my wife had a Maestro every time there was lightning locally the engine would stop. (Any one around Harrow/Pinner in the 80s remember seeing a white Maestro with steam coming out of the windows during thunder storms ?)


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## chadburn (Jun 2, 2008)

I have a Security Light outside at the rear of the house overlooking the garden, if the light comes on it sends a signal to a plug in unit inside the house, unfortunately I have had to stop using it as the signal interferes with the central locking both on my car and my neighbours, both cars are less than three years old from the Plant in Sunderland!!!


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## freddythefrog (Dec 15, 2007)

Was in the Pacific ocean early one morning calling GKA to get rid of W/T traffic, this was on the 6MHZ calling frequency, after about 10 mins calling the mate on watch says "what you doing sparks" the ships steering is going haywire.
I go into the bridge and everything ok, so I carried on calling GKA and the irate
chief mate says its doing it again sparks, it was making the ship turn to starboard, R/F getting into the Anschutz autopilot, I found the solution was to increase the earthing on the Crusader main tx and it never happened again.
It was only happening on the 6mhz calling frequency.
I also remember the Kelvin Hughes autopilot that if you put your finger on either the Port or Starboard driver transistors for the spool valves would also turn the ships rudder port or starboard. Happy days!


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## dab (Jun 7, 2007)

Greetings Rab, when was the new rasrig fitted. I was on Resource when new and again in 1970, don't remember any situation as stated!

Regards,
Dave.


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## King Ratt (Aug 23, 2005)

Hi there Dave. Good to see you on SN. I was in Resource Oct 85 to June 86 so it must have been during that period. The 4 mhz transmissions really upset the rig. I think it was nicknamed Snoopy.


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## Keith Rundle (Jan 30, 2015)

Ron Stringer said:


> Paul,
> 
> Yesterday when I looked up the reports of the incident I noticed that Serenia was given as the first ship on scene, so I too had my doubts about the story! But as Keith lives somewhere in Salisbury and rarely visits Chelmsford (I think he was on the way home from a trip up North), it may be another 40 years before I speak to him again.


Have just stumbled across this thread, so hello again Ron, it was great to see you all again!, and let me put the record straight.
I was R/O on S/T Mytilus at the time of the Marpessa/Mactra tragedies. We were nowhere near the Marpessa incident, but in fact on the other side of Africa, steaming north, 24 hours (ish) behind the Mactra at the time of the explosion. We established M/F W/T comms with her (she'd lost H/F antennas etc.), and relayed R/T comms to Shell Centre, London. We were expecting to assist as we had ironically just taken delivery on that trip of towing gear appropriate for 'M' class vessels. In the event, the Royal Navy, South African Navy, and Tugs out of Durban did sterling work, and we were not needed. I think (memory issues!) that another Shell tanker (Capisteria??) was also on scene.
On another subject Ron, I stood by Mytilus during construction in Japan, and yes, we did induce hard a'starboard turn via the autopilot (when we were on maiden trials) when we first fired up the Crusader Tx on 22Mhz!
Hope its not another 40 years to our next meeting!


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## Coastie (Aug 24, 2005)

I don't think I've ever experienced RF problems to any equipment, but I have certainly experienced an RF burn. OUCH!!! And that was only from a 50w TX!


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## Troppo (Feb 18, 2010)

My 2m amateur transceiver, complete with permanently mounted colinear antenna on the satcom mast, used to go straight into the bridge VHF on ch 16 when I transmitted on 146.1 MHz.

The bridge VHF had a 10.7 MHz IF..


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## Day Sailor (Nov 9, 2014)

One of the crew walking past the gyro compass holding a transistor radio had an 'interesting' effect on the autopilot on a yacht I was on.


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## Troppo (Feb 18, 2010)

R651400 said:


> Think 10.7 mhz was a status-quo VHF IF... Break-thru?


Oh yes, straight in.


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## david.hopcroft (Jun 29, 2005)

Needless to say GKZ often received complaints about RF interference. One such came from the Pub across the car park from us. Luckily the Radio Interference local Inspector was 'on our side'. He went across to the pub, took out a little hand held monitoring device, put a coin in each of their one arm bandits, turned to the landlord and said 'Right, switch off this one and that one - now what was your complaint ?' Owen was his name, lovely guy .

David
+


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## Ron Stringer (Mar 15, 2005)

david.hopcroft said:


> Needless to say GKZ often received complaints about RF interference. One such came from the Pub across the car park from us. Luckily the Radio Interference local Inspector was 'on our side'. I9tDavid


It always helps if the inspector is employed by the same boss as the organisation being 'inspected'. The police will confirm that.


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## Paul Braxton (Jul 21, 2005)

Referring to the original post, there was always the interesting ear burns from the metal parts of headphones when transmitting on certain frequencies using the Crusader...


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## Varley (Oct 1, 2006)

Paul, especially if one had forgotten to connect an aerial!

Using the Crusader on IF R/T could tune into the little parasitic choke on the PA of the Salvor (all litz wire, quite unrewindable) . Didn't use it like this often but still melted the little bugger.


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