# Marconi Lodestone DF Mk3



## John Leary (Mar 30, 2005)

Hi guys
In a moment of weakness, possibly madness, I promised my local radio club to do a brief talk on radio direction finding at sea in the 1960's

I know that there has been discussion in the Radio Room forum about using Direction finders but my enquiry is somewhat different.

There is a wealth of information on the Lodestone Mk3 on the Internet but so far I have been unable to find any photograph of the Goniometer or any schematic of the Lodestone's circuits, particularly the front end.

Is there an SN member who could help in any way. There is no immediate rush because the date set for the talk is later this year.

Any assistance would be much appreciated.

73's

John


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## King Ratt (Aug 23, 2005)

This might help, John.

Marconi UK Electronics

jproc.ca/britishmarconi/758e.html

7 Sep 2012 - The 'Lodestone III and IV' direction finders are very similar in appearance ... by Marconi International Marine, The Marconi International Marine ...


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## John Leary (Mar 30, 2005)

KR and R651400

Many thanks guys for your assistance which is valued and much appreciated. My search continues for a photograph of the actual goniometer with its screening removed and exposed in all its glory. Although I trained on and sailed with the Lodestone MK3 many times, I cannot recall ever seeing the actual goniometer .

Best regards to all.
John


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## charles henry (May 18, 2008)

*goniometer*

Long time ago and forget the name of the unit being replaced but the old one worked like a hot damn.
By comparison the loadstone was a piece of garbage.
Sailed and used both and thats my strong conclusion from many years ago.
chas


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## John Leary (Mar 30, 2005)

Hi all

Funny how fate can creep up on you when you least expect it but earlier today I was acting as a parking marshall for the first of my radio clubs two annual rallys when I walked up to a car where some punters were having a conversation. There sitting in the back of the vehicle was a goniometer! It was a circa 1950's avionic unit but close enough for my purposes as to make no difference.

It wasnt for sale (at least not to me) but the guy who owned it promised to e-mail me a photograph.

When I receive it I will post on the Radio Room forum for any one who might be interested to see what this posting was about.

As you might imagine I am chuffed to bits particularly as it was raining so hard most sellers stayed away and those that did brave the weather cleared off early.

73's

John


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## John Leary (Mar 30, 2005)

R651400

With luck like ours we should do the lottery!

73's
John


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## duncs (Sep 8, 2008)

Re Lodestone, I was on watch, usual pose, feet up, reading a book. About 0300lt, all quiet, then, almighty bang, bloody lodestone blew up! On inspection, found a capacitor(paper wound?) in the P.S. cct had exploded. Some mess. On replacement and cleaning up all was OK.
Otherwise, I found the Lodestone a good DF.


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## Hugh Wilson (Aug 18, 2005)

I liked both the Lodestar and the Lodestone DFs. Never ever had a problem with either and used them quite a lot in the late 60s/early 70s. I also found that the Autoguard add-on worked perfectly every time, provided the Lodestar was tuned to 500Khz and the 2nd mate wasn't listening to music on the midnight 12 to 4.


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## Ron Stringer (Mar 15, 2005)

duncs said:


> Re Lodestone, I was on watch, usual pose, feet up, reading a book. About 0300lt, all quiet, then, almighty bang, bloody lodestone blew up! .


At Brooks Bar radio college in Manchester, a rotary motor-generator arrangement (an a.c. motor running off the mains supply, mechanically-coupled to drive a 110v d.c. generator) was used during college hours to produce the supplies to run all the ship's radio room equipment (which operated from d.c., as was typical for many ships pre-1950s) and to charge the emergency batteries for the station via a voltage dropper made of resistance mats. The motor-generator and the batteries were located in the basement of the building and it was the job of "the last man out" each night to switch off the motor and isolate the battery charger.

One Monday morning we were sitting through some boring instruction about safety in the radio room, when there was a tremendous bang and we all went blind - in that we could see nothing other than dim light. Eventually things improved and we could see first a flickering light and then that the air was filled with glittering dust. When the dust cleared sufficiently for us to be able to see across the room, and we recovered enough from the shock to investigate, the problem was located as originating with the Lodestone DF. On opening it up, where the bank of large electrolytic capacitors (that formed part of the mains input filter) had been, were just some fragments of metal. The entire innards of the chassis and components of the DF were coated with a layer of what looked like a glittery papier maché - the former wound foil-and-paper contents of the electrolytics. 

It later became apparent that the person (never identified) who had turned off the motor before the college closed over the weekend, omitted to disconnect the batteries from the charging arrangements. Over the weekend the batteries had discharged through the d.c. generator and in doing so, had reversed the polarity of the machine's magnetic field. When it was started on the Monday morning, the output 110v. d.c. voltage was reversed and this was applied to all the radio room equipment. Only the Lodestone had a big bank of electrolytics fitted across the mains on the supply-side of the equipment's on/off switch. So although the Lodestone was switched off, the filter was still connected to the mains. After an hour or so of reversed voltage, the electrolytics gave up the struggle in a big way. It took several days to remove the debris from inside the Lodestone and to restore it to full working order. 

It took almost as long for our nerves to recover. I believe that shortly afterwards, modifications were made to the charging arrangements in order to prevent any recurrence of the incident. (Jester)

I sailed with both Lodestone (various versions) and Lodestar I and found them to be very reliable and useful instruments.


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## Ron Stringer (Mar 15, 2005)

R651400 said:


> Would Brookes Bar ac motor driving a dc generator be the 1950's norm?


Sorry but I can't tell you that because my only other college experience was at South Shields where everything operated from a.c. (as best I can remember!).


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## duncs (Sep 8, 2008)

Ron Stringer said:


> One Monday morning we were sitting through some boring instruction about safety in the radio room, when there was a tremendous bang and we all went blind - in that we could see nothing other than dim light. Eventually things improved and we could see first a flickering light and then that the air was filled with glittering dust. When the dust cleared sufficiently for us to be able to see across the room, and we recovered enough from the shock to investigate, the problem was located as originating with the Lodestone DF. On opening it up, where the bank of large electrolytic capacitors (that formed part of the mains input filter) had been, were just some fragments of metal. The entire innards of the chassis and components of the DF were coated with a layer of what looked like a glittery papier maché - the former wound foil-and-paper contents of the electrolytics.
> 
> It took several days to remove the debris from inside the Lodestone and to restore it to full working order.


Thanks Ron, for info. It's interesting to know that my experience(Lodestone), was not unique.
In my case, I think it's just as well that the D/F was in the radio room, rather than the chartroom.

Regards,
Duncs


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## John Leary (Mar 30, 2005)

Hi Guys

A friend in the radio club has been in touch with the guy who owns the goniometer I mentioned in an earlier posting and I have just received the promised image of the avionics goniometer which is attached.

My planned talk to my radio club on Marine DF is as much about the use of DF at sea as it is about the equipment making up the DF system, but I was always facinated by the internal workings of the Loadstone and in particular the goniometer so to have found an image of an item that approximates to those used at sea is a real find.

Thanks again to all who helped in my search and for the contributions to my original posting.

Best 73's

John


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## GW3OQK (Jun 10, 2010)

You can buy a very nice DF loop John http://www.ebay.co.uk/itm/Marconi-Direction-Finder-Architectural-Salvage-Nautical-Ship-Sculpture-7ft-WW2-/141091445396?pt=UK_Antiques_Marine_RL&hash=item20d9b49a94


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## John Leary (Mar 30, 2005)

GW3OQK/Andrew

Thanks for the link. I had seen the posting but decided if I had the sort of money the owner is asking for the loop I might prefer to spend it on something less decorative like a high-end software defined radio transceiver.
Regards
John


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## GW3OQK (Jun 10, 2010)

John, do you remember the advantage given by using wire loops inside metal tubes? At your talk someone might ask how you manage to receive anything on the loop wires if they are inside metal tubes. (I know the answer) I never recall seeing a brass loop, they were all painted, or were there some ships where the jr/o was sent up with brasso and a rag every week.
Andrew


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## frank beech (Apr 23, 2014)

*loadstone D.F. receiver*

Hi John.
Re the Loadstone schematics etc. Have you looked at the old "Dowsett and Walker" book,( Technical instructions for Marine Radio Officers.)

I still have a copy, ninth edition 1950.
It does have a circuit diagram for the loadstone type 758 receiver together with notes and diagrams of the antenna and adjustments but no photo of the actual coil assembly you require.
If it would be of any assistance to you I could print off a copy for you.
I had a couple of years on what was the empire aden in the 1950,s, and in those days before radar was common, used the df very often.

Regards from Tasmania.
Frank Beech


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## John Leary (Mar 30, 2005)

GW0QK/Andrew and Frank

Many thanks for your responses. Andrew my understanding is that the loop frame was made of a non magnetic material in order to provide mechanical strength and to balance the loop wires to earth in order to reduce the impact of capacitive unbalance on the input to the receiver. Furthermore it was made discontinuous by the provision of insulators in order to prevent the casing screening the loop wires from the wanted signals.

Frank. I have sent you a PM regarding your kind offer.

Best regards and 73's to all
John


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## GW3OQK (Jun 10, 2010)

John, I was looking for info and this text book below is for sale and you can read some of its pages. 

I think the shield prevents reception of interfering electrostatic fields but passes wanted electromagnetic fields, but it looks like there is much rubbish on the internet about it and I'm not really certain. I always was impressed with signal strengths from the loops and the very sharp nulls produced. To me the manual DF was much more accurate than the automatic.

Then when night fell distant signals would disappear. 

Andrew




http://www.ebay.co.uk/itm/DF-RADIOLOCATION-ADMIRALTY-WAR-OFFICE-AIR-MINISTRY-TOP-QUALITY-SERVICES-BOOK-/261489395377?pt=UK_Mobile_Phones_Communication_Radio_Antennas&hash=item3ce1fb86b1


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## John Leary (Mar 30, 2005)

GW3OQK/Andrew
Many thanks for the link. Funnily enought I bought this book new in 1961 when I was at the Wireless College in Colwyn Bay. The Services Text Book of Radio were a new series and at that time not all of the volumes had been published. I paid 15 shillings for it then (75p in new money) so the £28 now being asked represents either a reflection of how money has devalued over the last 53 years or the rarity of the book. Either way I'm keeping mine. Many thanks for looking out for me.
73's
John


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## trotterdotpom (Apr 29, 2005)

The problem was, the paint everything ABs would lather the whole loop in paint, including the insulator bit. 

John T


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## John Leary (Mar 30, 2005)

John T
Even worse was the threat of using a chipping hammer to remove the old paint before the new coat was applied!
Regards
John


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## duncs (Sep 8, 2008)

My memory of the loops on both the 'Sirdhana' and the 'Dwarka'(71/72), were polished brass. No paint!


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## trotterdotpom (Apr 29, 2005)

duncs said:


> My memory of the loops on both the 'Sirdhana' and the 'Dwarka'(71/72), were polished brass. No paint!


Did you stand guard over it? Is that why so many folk reckon that Sparkies were loopy? 

John T

PS who kept it polished?


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## Varley (Oct 1, 2006)

I did remove the red paint from one new installation's transmitter aerial tubing and keep the copper polished. It revealled that the depot/agent responsible for outfitting had joined scraps of tubing together with a brass plug.

Never had any bother with the DF loops 'though.


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## duncs (Sep 8, 2008)

trotterdotpom said:


> Did you stand guard over it? Is that why so many folk reckon that Sparkies were loopy?
> 
> John T
> 
> PS who kept it polished?


Definitely not me, John. It must have been started by predecessors, maybe the cadets did? Same as the morse key cover was scraped and polished brass. Ditto the tuning knobs on the Mercury and Electra, plastic removed and polished brass, which could be a pain in the a*se(sorry, fingers), when, on a humid night, fine tuning to GKA getting tingles in the fingers.
However, that's nothing. I had a disgruntled 2/RO visit me from the 'Karanja', who complained that the C/RO had him brassoing the main aerial when it was lowered in port.
You mentioned loopiness!

Duncs


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## trotterdotpom (Apr 29, 2005)

I thought I was OCD for polishing the copper tubing in the wireless room, but I realise now that maybe I wasn't too bad. One time during a long anchorage, I scraped the paint off a porthole and polished it - I bet my relief thought I was a right dickhead. When I was a lighthouse keeper, there was so much brass to polish, nowadays I can't bring myself to touch shiny brass without a hankie in 
my hand.

Making a junior polish the aerial wire is beyond OCD, sounds like bullying to me. The Junior should have told him to go forth and multiply.

John T


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## duncs (Sep 8, 2008)

trotterdotpom said:


> Making a junior polish the aerial wire is beyond OCD, sounds like bullying to me. The Junior should have told him to go forth and multiply.
> 
> John T


He wasn't a Junior, he was a watch keeping 2nd RO on a class 1 vessel(is that right for a passie boat?). And yes, it was obvious bullying on the part of the C/RO. I met the guy, a REOU delegate, and he was nice as pie(to me). 
OCD, loopy, who knows?

Duncs


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## Ron Stringer (Mar 15, 2005)

The Chief R/O on E & F's _Golfito_ insisted on the radio room copper tube being brasso-ed (and woe betide if there was any trace of white powder deposit or verdegris left behind afterwards). I was the 3rd. R/O and had to do the polishing. When he took the Christmas 1960 trip off on leave, I got some paint from the engine room and painted it all fire engine red.

When he returned from leave he went ballistic but I told him that it had been done by the MIMCo technicians from Southampton depot because of new safety rules related to the presence of passengers in the radio room when making link calls. He swallowed it hook line and sinker and I had no more brasso-ing to do. When I left the ship a couple of trips later, all was still fire engine red. Looked lovely, I thought.


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## trotterdotpom (Apr 29, 2005)

duncs said:


> He wasn't a Junior, he was a watch keeping 2nd RO on a class 1 vessel(is that right for a passie boat?). And yes, it was obvious bullying on the part of the C/RO. I met the guy, a REOU delegate, and he was nice as pie(to me).
> OCD, loopy, who knows?
> 
> Duncs


Even worse. He should have stuck up for himself .... Who would do such a ridiculous thing? Come to think of it, what sort of Union Delegate was the CRO?

John T


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## Wismajorvik (Dec 29, 2011)

Ron Stringer said:


> The Chief R/O on E & F's _Golfito_ insisted on the radio room copper tube being brasso-ed (and woe betide if there was any trace of white powder deposit or verdegris left behind afterwards). I was the 3rd. R/O and had to do the polishing. When he took the Christmas 1960 trip off on leave, I got some paint from the engine room and painted it all fire engine red.
> 
> When he returned from leave he went ballistic but I told him that it had been done by the MIMCo technicians from Southampton depot because of new safety rules related to the presence of passengers in the radio room when making link calls. He swallowed it hook line and sinker and I had no more brasso-ing to do. When I left the ship a couple of trips later, all was still fire engine red. Looked lovely, I thought.


On my first trip the senior R/O would, in addition to polishing the copper tube feeders, use furniture polish on all the equipment and remove all the brass screws from the woodwork in the shack, brasso them and screw them back in again. As he had done the latter for many years the screws were pretty loose! My attempts to polish the screw heads in situ caused some grief.
Good times......


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## trotterdotpom (Apr 29, 2005)

Wismajorvik said:


> On my first trip the senior R/O would, in addition to polishing the copper tube feeders, use furniture polish on all the equipment and remove all the brass screws from the woodwork in the shack, brasso them and screw them back in again. As he had done the latter for many years the screws were pretty loose! My attempts to polish the screw heads in situ caused some grief.
> Good times......


Er ... maybe we should stop giving away all these Sparkie secrets. The rest of them might get the idea that we were eccentric.

John T


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## trotterdotpom (Apr 29, 2005)

Don't think any of that nonsense was Mimco policy. Not sure what QTP "light fingers make less work" means. I am entering port and stealing stuff?

John T


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## Varley (Oct 1, 2006)

trotterdotpom said:


> Don't think any of that nonsense was Mimco policy. Not sure what QTP "light fingers make less work" means. I am entering port and stealing stuff?
> 
> John T


Was that my metaphor? If so it was badly mixed. I have never criticised what we did do only pointed out it was rarely that important. I criticise for the opportunity we had and which we (or most of us) failed to grasp, with the REOU "encouraging to fail" (In the unlikely event you are on watch up there George, I don't include you).

Retrospectively, of course (who can argue with hindsight), and evidenced by the few numbers of qualified western electrical types still at sea, the coalface would not have continued as a volume career entry point.


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## trotterdotpom (Apr 29, 2005)

No, David - not your metaphor, it was the smart alec pseudo Frog.
john T


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## Troppo (Feb 18, 2010)

I remember very well the increase in antenna current when I replaced the main antenna.....so there could be a method in the Chief's madness...mind you, light sandpaper would have been more effective than Brasso...


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## George McCaffery (Jun 17, 2006)

Ron Stringer said:


> The Chief R/O on E & F's _Golfito_ insisted on the radio room copper tube being brasso-ed (and woe betide if there was any trace of white powder deposit or verdegris left behind afterwards). I was the 3rd. R/O and had to do the polishing. When he took the Christmas 1960 trip off on leave, I got some paint from the engine room and painted it all fire engine red.
> 
> When he returned from leave he went ballistic but I told him that it had been done by the MIMCo technicians from Southampton depot because of new safety rules related to the presence of passengers in the radio room when making link calls. He swallowed it hook line and sinker and I had no more brasso-ing to do. When I left the ship a couple of trips later, all was still fire engine red. Looked lovely, I thought.


Hi Ron I was third R/O on the Golfito in 1969 Dick Ware was 2nd
and George Sullivan? was CRO I can't remember if the copper was still red.


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## George McCaffery (Jun 17, 2006)

Reading this thread i feel i was very lucky. I sailed on my first trip as junior on the E&F Chicanoa with Maurice Meehan a lad from Belfast who was just a pleasure to work with/for.
I had 2 months to finish my 6 months which i completed on the E&F Golfito
George Sullivan was the chief and although i can't say i thought the world of him i think he was fair.
I later sailed as 3rd R/O on the RMS Andes and Johnny Hands was the Chief
and i got on great with Johnny, a very fair man. Thinking back i wish i had stayed longer but was keen to go back to cargo vessels.


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## George McCaffery (Jun 17, 2006)

Sorry the CRO on the Golfito was George Sutherland. Memory problem.


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## duncs (Sep 8, 2008)

George McCaffery said:


> I later sailed as 3rd R/O on the RMS Andes and Johnny Hands was the Chief
> and i got on great with Johnny, a very fair man. Thinking back i wish i had stayed longer but was keen to go back to cargo vessels.


Hi George, I was 2nd with John Hands on the 'Sirdhana'. A real gentleman.
He told me some great tales re the 'Andes'.
When the 'Andes' went, he went to the 'Golfito'. When she went, he landed on the 'Sirdhana'. When it was decided the 'Sirdhana' was destined for razor blades, John left and I took her to the scrapyard in Taiwan.
I don't know what became of him after that.

Duncs


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## duncs (Sep 8, 2008)

Ron Stringer said:


> The Chief R/O on E & F's _Golfito_ insisted on the radio room copper tube being brasso-ed (and woe betide if there was any trace of white powder deposit or verdegris left behind afterwards). I was the 3rd. R/O and had to do the polishing. When he took the Christmas 1960 trip off on leave, I got some paint from the engine room and painted it all fire engine red.
> 
> When he returned from leave he went ballistic but I told him that it had been done by the MIMCo technicians from Southampton depot because of new safety rules related to the presence of passengers in the radio room when making link calls. He swallowed it hook line and sinker and I had no more brasso-ing to do. When I left the ship a couple of trips later, all was still fire engine red. Looked lovely, I thought.



Ron,

I just love that.

Duncs


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## Ron Stringer (Mar 15, 2005)

George McCaffery said:


> Hi Ron I was third R/O on the Golfito in 1969 Dick Ware was 2nd
> and George Sullivan? was CRO I can't remember if the copper was still red.


In 1960/61 the Chief was P J Kelly. Other SN members sailed with him but as at least one of his children is also a member, I would ask that any comments are carefully considered before posting. [=P]


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## George McCaffery (Jun 17, 2006)

duncs said:


> Hi George, I was 2nd with John Hands on the 'Sirdhana'. A real gentleman.
> He told me some great tales re the 'Andes'.
> When the 'Andes' went, he went to the 'Golfito'. When she went, he landed on the 'Sirdhana'. When it was decided the 'Sirdhana' was destined for razor blades, John left and I took her to the scrapyard in Taiwan.
> I don't know what became of him after that.
> ...


I didn't come across John after the Andes unfortunately, I think one of the other R/O's was Willie Nicol if i can trust my memory.


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## Duncan112 (Dec 28, 2006)

At Carlisle airport at the weekend to see the Vulcan on her farewell tour - wandered round the museum and on the wall an unwrapped goniometer - as most of the WW2 RAF radio gear appeared to be Marconi derived I attach a photo.


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## Naytikos (Oct 20, 2008)

posted by Ron Stringer:


> _Sorry but I can't tell you that because my only other college experience was at South Shields where everything operated from a.c. (as best I can remember!)._


Plymouth doesn't count, Ron?


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## Ron Stringer (Mar 15, 2005)

Naytikos said:


> posted by Ron Stringer:
> 
> 
> Plymouth doesn't count, Ron?


Blame it on Old Age! Maybe a contributing factor was because the 5 months spent at Plymouth wasn't a on course that I funded or chose to go on and by then I had left the sea, so in my mind I was no longer a Student R/O. And, of course, it too was A.C. powered.


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