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Kelvin Hughes equipment at Internal Fire

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#1 ·
Many of you have followed the fortunes of Internal Fire-Museum of Power in 2019, culminating in the successful restoration of our rare Marconi Challenger ( See thread "Marconi Challenger"). This thread will follow the restoration of of the Museum's Kelvin Hughes S1250 Zealand transmitter. This is a 1.2KW transmitter, providing A1, A2H, F1, A3H, A3A and A3J modes. It is fully synthesized and as Troppo2 testifies operating on amateur bands should not be a problem! Unlike the Challenger saga, we do have a full set of manuals for this equipment, as well as some spare parts and some complete units.
The equipment originally came from GURK: RFA Orangeleaf. I believe that the console, transmitter and spares were rescued from scapping, by a vigilant member of the Marine Radio Museum Society Wallasey who liberated it when KH were moving premises in Liverpool. It was on display for some years at the Radio officer's museum at Fort Perch Rock on the Wirral. We obtained it in September 2016 when the Radio Officer's Museum sadly had to close. (Someone may well be able to fill in some of the history here).
The receive side is all working, the main receiver is very sensitive and stable, the reserve receiver is OKish. Its hardly more than an elaborate entertainments receiver. In its defence, it is in need of re-alignment as the dial is about 500KHz out on some bands, it has dead spots and a mechanical overhaul is needed as the tuning action is jerky making it hard to tune accurately.
I've run in a 3 phase supply for the transmitter, the loom is present (I think) so interfacing with the console should not be too hard.
Someone has robbed all the components form the antenna switch, more importantly the antenna loading coil, and plate tuning capacitor together with some high voltage capacitors have gone missing from the HF ATU. I've collected some suitable parts over the last couple of years, but although the values and ratings are OK, the physical shape and size of the capacitors may need some jiggery-pokery to fit into the available space. This will be the first job and I will report on this later.
Attached are some pictures to be going on with.

Best wishes - Michael.
 

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#2 ·
Thanks for your photos, Mr. Oceanspan (VI or VII, I wonder?) Probably Oceanspan VIIE... Appreciate your care and thoughtfulness with the emails and attached photos. Always nice to check them out; first thing I always look for, every time I access the SN site.

Best wishes to you, too, and good luck with the museum and the challenges (no pun intended) lying ahead.

Paul GRUA
 
#3 ·
I was Service Manager at Kelvin Hughes in Singapore 1997-2001 and by then the company had stopped manufacturing radio equipment. We had an OEM agreement with SP Radio in Denmark to supply their GMDSS consoles under the name Husun.

This thread is very interesting and I will follow your progress and wish you luck with the refurbisment.
 
#6 · (Edited)
Michael: GRUA was Shaw Savill's "Mayfield", one of their first forays into faster turn-around, part containerisation vessels. She had been a Scandinavian registered vessel before that, I believe, though can't remember the previous name.

I use the c/s as it always reminds me of a particularly innovative and interesting time for me as an R/O. 1977, (in addition to being infamous for Elvis' death) was a good year for new equipment, at least as far as I was concerned. Talking to the London office using the realtime ARQ telex setup at long range with Portishead was so rewarding. Having the Old Man and Chief Engineer sitting there, me translating their queries and comments onto the keyboard of the teleprinter and seeing an immediate response was really rewarding. Such a difference from the old days of carefully worded telegrams and often flakey R/T calls at long range. I had just completed several consecutive and long trips on some of SS&A's older ships and was desperate to stay with the company, although still working for Marconi of course. The men at East Ham Depot were understanding enough to accommodate that, and in order to efficiently man a ship with the Spector telex/Commandant TX, sent me off to do the respective courses before going out to join "Mayfield", which was on the West Indies/Southern U.S./NZ run.

What more could I have asked for? One of the best runs at the time, certainly for me, and I was so pleased to get away from the Oceanspan setup at long last, to get behind some decidedly serious equipment for a change. Others were attracted to the new Marconi gear as well. I had a series of visits in Houston from some guys who were serious enthusiasts, and who came down to the ship with the purpose of having a really good look over the gear, going away with lots of talk about buying a Commandant/Apollo for their very sophisticated-sounding set-up, complete with its 'antenna farm', as they termed it. They were really into it, to the extent of asking me to set up an unofficial 'sked' with them while we were west-bound out of Panama, so that they could gauge the effective range achievable, etc. The Commandant didn't let me down. Nothing wrong with your namesake, of course, just felt the need to 'spread the wings' a little, see how the new technologies were shaping up. As a result of all this, the ship and its c/s became a big part of my sea-going memories, hence the tag.

I made up a wooden plaque, some time ago, with the painted c/s 'GRUA' attached, to accompany my genuine radio room clock, mounted above the Atalanta in my back room. Although I say so myself, it does look the business, as they say, and is a constant and stirring reminder of those halcyon days when I cavalierly roamed the seas and oceans. All I might need now is the wooden plaque: 'RADIO ROOM', on the door! Only partly joking, such is the severity of chronic reminiscing...

I'll attach a photo of the setup sometime, if I get round to it, complete with the Marconi 365B morse key, and the 2015 edition of ALRS Vol 1, which was gifted to me at the same time as the key and clock by a good friend, ex NZS and Aussie Coast R/O.

All I want now is an Apollo RX, but that's probably not going to happen, as they're rare as hens'. The transition from the old Oceanspan/Atalanta days to the more modern equipment was something else, I can tell you. I've probably said it before on here, but I only wish I had kept my very carefully annotated Mimco manuals for them all, (works of art in their own right), as the training courses we attended at various places around the UK were very well structured indeed, and gave you a hell of a lot of confidence that you could find your way around the equipment before finding yourself at sea with it.

I think they were a bit underrated sometimes, that structuring in of all those various Mimco courses. For me, they were a much looked-forward to and enjoyable experience. I'm a staunch, signed-up champion for Marconi Marine, as you can tell! Even when they sent me on the odd 'bum' trip, like taking a dredger over the North Sea, or a converted Hull trawler doing pipeline surveys with side-scan sonar, etc, ignoring my perfectly reasonable request to be allowed to stay at home and watch the 1978 World Cup... It was all good for the soul, overall 'character building', you might say, the 'University of Life'.

Nice talking with you, as always. Keep up the good work. Never yet met a ceramic type valve. Sounds interesting.

Paul/GRUA
 
#26 ·
All I might need now is the wooden plaque: 'RADIO ROOM', on the door! Only partly joking, such is the severity of chronic reminiscing...


Paul/GRUA
Hi Paul - I know this is an old thread but a few years ago I too hankered after a "W/T OFFICE" sign for my reconstruction of a MIMCO stn. 'Span 7, Mercury/Elettra/Atalanta, Salvor, AKD, AA Rx - the lot!

So, I had a batch cast in bronze/brass and flogged them.

Then I got EVEN MORE requests for "RADIO ROOM" so I had several batches of those made up.
I have but ONE (1) left for sale! They are 15cm long by 5cm wide - solid.
They are polished to a gleaming shine, enough to satisfy even the nastiest Captain on his Sunday morning inspection!

Michael from MOF will tell you how nice they are as the Museum Shack has one of them.

PM or whatever they call it on here for details if you are interested.

=RGDS=BRUCE/GW4XXF=+
 
#7 ·
Paul - I was on the Mayfield from December 76 to May 77, my first ship with telex. Joined on the Tyne, where she'd been modified for containers. As far as I can remember, the first voyage was to NZ via Panama, but a week into the voyage it was discovered that the stern tube had received no, or inadequate, lubrication, and was badly damaged. We limped into Curacao for repairs, and were there for about two weeks.
Pitcairn was a waypoint on the way to NZ. Captain (Davies?) told me that the local radio station would call once we were visible from the island, but I was not to respond, as they'd be scrounging freebie stores. I couldn't resist the temptation though, and had a short chat with Tom Christian. Eventually paid off in Port of Spain.
 
#8 · (Edited)
Hi Criffh. Now that is interesting. Looks like I relieved you on there, but don't remember having a hand-over chat, probably because you guys had already made your way to the airport when we arrived. According to my records, I joined in Port of Spain, 14th May and left her in the same port, 25th Sept. '77. Captain Hills has signed my discharge book, so it must have been a complete crew change.

That's interesting about Pitcairn Island. These stories are a part of history now. I unfortunately only called at Pitcairn as a babe in arms, on 'Rangitane', in 1952, or 53, so don't remember them coming out with souvenirs to sell, although many's the time I've had the story from my mother, and I still have a very solid and nicely carved flying fish as a permanent reminder of days long gone, sitting proudly on my bookcase. It is stamped on one 'wing' by the maker, one Oscar Clark (wonder if anyone on this site remembers him, and whether he might have been a descendant of one of the mutineers?)

Your QSO with Tom Christian reminds me of a similar one I did with the station on Easter Island/Rapa Nui, in the mid or early '70's. I think the callsign was something like CBY, perhaps. Had quite a long chat with the guy there, but had to wait until 2001 to actually spend some time on the island, a place which has always had me enthralled since I was a kid. The locals were really interested in my mentioning having been on a passing ship and chatting with the operator back then in the '70's. My casual comment about it started quite a buzz in the large meeting hall, with lots of people trying their hardest to remember who it might have been, where he was now living, etc., though I never did find out, or get the chance to have a catch-up chat, this time in person, in rusty Spanish, no doubt. I had only called him up on spec, just wanting to say "HI" as we passed. He was really pleased to have had someone to talk to on air. Those were the days!

It really was a dream, that telex gear, at least it was for me. The only thing that ever went wrong was a mechanical part in the teleprinter, which had the C/E and his best fitters scratching their heads to make a temporary replacement for what was an essential moving part, to try and enable a continuation with the excellent ship to shore service it afforded until a new part came out. Ray Contreras (the Chief), was a thoroughly good guy, as I've mentioned before on this site. He did a similar job in making a new moving part for the Walport film projector (Bell and Howell?), (essential equipment!) which didn't last long, as it had to be made out of very hard, tempered steel, which they apparently didn't have.

All the best, with memories of a great ship, Paul
 
#9 ·
Hi Paul
My discharge book payoff date was 15/5/77, so there's no doubt about the fact that you relieved me. I eventually packed the sea in in 1985, when the writing was well and truly on the wall. Sailed mainly on T&J Harrison ships after GRUA. All their ships had modern Mimco gear and telex fitted, and provided considerably more spares than BOT/DTI requirement too. Crews were pretty good, mostly from the northwest of the UK (me being a 'foreigner' from the south). Didn't see much of the Pacific islands other than a few phosphate runs to Aus from Nauru. One time we spent several months drifting off Nauru, unable to berth due to the wind being in the wrong direction. Quite a contrast compared to modern times, where the proverbial would hit the fan if the ship was running an hour behind schedule.
I see your QTH is NZ. Nice place, I've not been back there since the Mayfield days. Still reside in the UK, but spend around 6 months of the year in Spain and Thailand. Name is actually Cliff Hawkridge (Criff acquired when I was working in Korea, where I was known as Mister Criff).

No doubt about it - R/O was the best job on the ship!
 
#10 ·
#9 . I think drifiting time was built into the Charter Party on those phosphate runs, Criff. The ships hardly ever got straight alongside. Did get into Christmas Island one time, mainly because we had a hold full of fresh water for them and they were desperate.

Passed Pitcairn a couple of times but never made contact. Apparently you can go and stay there now ..., but don't take your kids!

John T
 
#11 ·
Nauru - during our long wait to go alongside we would drift westward for, as far as I can remember, five days, then take two days to steam back. This gave us the opportunity to make fresh water. Not enough though, and on one occasion we took a trip to Honiara, just for fresh water. A fascinating place. Another incident was the rescue of a lone sailor who'd been caught in a storm and had been drifting for days, sails ripped to shreds, and motor seized. He was lucky enough to have drifted in vhf range Nauru, with enough power left to contact the island. C2N relayed the mayday, and we located him. He got safely off his ferro-concrete hull boat, which sunk immediately after it came into violent contact with our hull.
We were head of the queue for the loading berth, and every morning I would send the same message to C2N "Is today a wwd", to which he would respond with a question mark. So I'd send "Is today a weather working day?" Usually after several repeats, I'd get the anticipated "no".
Christmas Island... I think I was too scared of all those crabs to go ashore!
 
#12 ·
Hi back, Cliff. What part of the UK do you hail from, I wonder? I lived for a time in the southwest, Sussex and latterly, Dorset, before moving out to NZ in 07. We now live just north of Rotorua, out in the countryside quiet. I was brought up in NZ and lived here, on and off for a large part of my life, before finally coming out to stay for what I hope is for good.

I agree wholeheartedly: R/O was the best job; nowt to do and filmstar wages, as was often the jibe aimed my way. I'd do it all over agn any time.
 
#14 ·
Paul - Originally from Worthing, then moved along the coast to Littlehampton, where I've lived for the past 40 years. Bought a house off-plan while I was still at sea, but was delayed moving in when I came home on leave because the central heating couldn't be installed, due to a national shortage of copper. The irony was, I'd returned to Avonmouth from the west coast of S.America with about 10,000 tons of copper aboard PSNC Oroya/GXUT.
Went to sea in '67 and packed it in in '73 after suffering two captains who took great pleasure in bullying young R/Os. I'd read up about colour tv while at sea, and got a job ashore with Visionhire. Got frequent letters from Mimco re improved pay, conditions etc. trying to entice me back. There was a major R/O shortage at the time. I missed the sea though, and was eventually lured back. After one year and 51 weeks of being ashore, I phoned Marconis and asked them if they could find me a ship within a week. They welcomed me back with no loss of seniority, and got me on mv Sugar Refiner/GOYK at 51 weeks and 6 days. Always had decent ships/gear after that, and GOYK was one long party! Fast forward to Mayfield, berthed in Auckland. I was walking around the city and came across a tv workshop. Out of curiosity I went inside, and told them that I had all the Visionhire qualifications in colour tv servicing. I had a job convincing them that I had no desire whatsoever to jump ship! Colour tv back then was very new to NZ, and they were very short of trained people.
 
#16 ·
G'day Cliff! Amazing!! I was on the 'Sugar Refiner'/GOYK as well, but in '78, so a bit after you. No wonder I recognised your name. Must've noticed it somewhere in the records at the time. I thoroughly enjoyed my time on the 'Refiner' as well. She was a great ship, with good people. Now I find myself wondering what other ships we might have 'shared'...

I was at sea from '69 to '82, the whole time with Marconis, out of East Ham, since I was living in Kent and East Sussex at the time. Like you, again, I copped a shoreside job by 'coincidence', after having a chat with a taxi driver in Auckland, who pointed me, in '82, to Pye, an electronics company with a big business concern on the Coromandel coast, over to the east, and within a day or so, after fronting up and presenting myself and my impeccable Marconi qualifications and experience (hmm....) had a cushy, if extremely busy sort of job in the consumer electronics industry, which served me well until the place went bust a few short years down the line and I returned to UK for a while. I get around, as you can see.

Interesting, how Marconis seemed to be able to accommodate some R/O's wishes like they did with at least the two of us. A lot of dynamics going on there behind their venerable scenes which wasn't immediately obvious to a young, inexperienced lad. I think it was a case of rubbing each others' backs when there was an unreachable itch! I did two really good trips with Sugar Line, the other being in '73, on the 'Crystal Diamond', giving me the odd distinction of having served on two ships with 'M' c/s, the other, 'Sirsa', of BI, back in '71, which gave me the memorable trip to communist China for a whole month. An interesting if somewhat scary experience, which I will hopefully (given time!) be incorporating at least in part, into a book I'm currently writing.

Nice to have a QSO with you. Interestingly again, I did a few trips on Port Line, to Peru as well, and so pleased I got the chance to do so, as I never went back again. That was way, way back in the very early '70's.

Nice to talk with you, Cliff; '73's and have a good day. Paul
 
#17 ·
Hi Paul
I did 10 months on the Refiner, the first 6 were runs between Silvertown (Tate & Lyle berth) and the Caribbean. She was on charter after that, and I and several others requested to stay on. It was then to Baton Rouge, then Chittagong and Chalna. Not the best of places to visit, and by the time we left for Aus we'd almost run dry. Replenished the bar when we picked up the Thursday Island pilot. As far as I can remember, we loaded sugar in Mackay for Silvertown, where I paid off.
Here's a chronological list of the ships I sailed on, from discharge books:
Sir Andrew Duncan/MYBN Denholms 6 months junior R/O
Rossetti/GVMX Lamport & Holt 2 years 3-4 month trips between UK and Brazil
Newcastle Star/GVRS Blue Star Line 6 months on run between S.Africa & Aus
Teviotbank/GRFH Bank Line 4 months
Texaco Bahrain/GQNB
Melbrook/? 6 months bloody awful !
Avon Bridge/? Denholms 6 months
....2 years ashore....
Sugar Refiner/GOYK
Jeddah Crown/ELXT 4 months
Mayfield
Sugar Producer/GYNL T&Lyle 4 months Great Lakes
Esso Warwickshire/GJVE 2 months North Sea 7 European ports
Oroya/GXUT PSNC 6 months west coast S.America
Wanderer/GRHA T&J Harrison 6 months x 3 voyages bulk carrier
Astronomer/GVOC T&J Harrison 6 months container Europe - Caribbean/central America
City of Durban/GXIC Harrisons/Ellermans 4 months Container Europe-S.Africa
Specialist/GUVU T&J Harrison 6 months bulk carrier
Adviser/GXES Same as Astronomer
Warrior/GRHB T&J harrison 6 months Bulk carrier
Benvorlich/GREE Ben Line 6 months Bulk carrier
Author/GBSA Same as Astronomer Final ship

There are stories to tell on all those trips! I'll bore you with a few.

Newcastle Star: Actually joined in Liverpool. Anchored for 24 hours outside the port (at the Bar) because of thick fog. A 9,000 ton ship with no radar fitted!
Teviotbank: Half way through my leave and Marconis phoned. Would I come back early and join a Bank boat? I told them to stuff it, as it was an old ship, and Bank Line trips could last up to 2 years. Ten minutes later another phone call. Would I join another Bank boat, a new ship with a/c and a swimming pool, plus the promise to get me off within 6 months! How could I refuse? The old man was a right pain, but it was otherwise a good ship. After 4 months we arrived in Durban. The OM called me, and asked if I'd made a complaint against him (something he was probably used to). I told him I hadn't, and he asked why a relief was flying out to replace me the following morning. They'd actually kept their word, which I hadn't expected. If they'd had asked me a few days earlier, I'd have told them I was happy to stay on the ship. Just as well I got off though, the Indian coast followed Durban.
Texaco Bahrain: 10 month trip, half of that at anchor before she was eventually scrapped in Kaohsuing, Taiwan.
Jeddah Crown: Had to get a Liberan ticket for this one! A new-build, the lecky and myself were the first to fly out to the shipyard, even before the old man or chief eng. I refused to go aboard, as the only way to board involved walking along the hatch combing of an open hatch.
Sugar Producer: On our way back to Belfast from the Great Lakes, someone was deliberately damaging deck items, or throwing them overboard. One thing I remember is the fuses for the for'd nav lights going missing. The OM requested police board on arrival Belfast. Payoff was delayed and there was no shore leave. Two police detectives set up an incident room next to the bar, and interviewed, amongst the officers, the third mate and 4th engineer, who had been implicated by the crew. It just happened to be the 3rd mate's 21st birthday, and celebrations were underway in the bar. Round about 10pm, the police came into the bar, grabbed the 3rd mate, and dragged him to the gangway, kicking and screaming. Then they let him go, wishing him a happy birthday. They'd already decided the culprit was the first-trip deck boy, who was a nasty little sh*t.
Astronomer: After I paid off this ship, she was requisitioned for the Falklands war, and Marconis try to get me to rejoin, as I'd done a Predictor radar course. No was was I going to volunteer to get bits of my anatomy shot off, and they found someone else. As it happened, by the time Astronomer reached the Falklands, the war was over, and I was on the Wanderer, stuck anchored off Aden for weeks with busted a/c !

Well, that's my life story. I was happy to stay with Marconis throughout my time at sea. The pay wasn't as good as foreign flag, but at least you could keep your sanity.
Very nice to have a QSO with you too Paul. Rare to bump into anyone who know what the Merchant Navy is/was, let alone an R/0.
So what will the book you're writing be about?
 
#21 ·
Progress on Kelvin Hughes - at last!

It’s been all go at the Museum since we closed last October. A lot of progress has been made on the Kelvin Hughes, but there are still a few issues to resolve before it can be turned on. On-Site work at the Museum has stopped as it is now in lockdown owing to the Coronavirus. My wife and I are keeping ourselves as isolated as possible, but making sure we get a few hours outdoors exercise each day. On the last day that I was able to go to the Museum I brought various bits and pieces home for repair or modification: The Challenger synthesizer to be modified for Amateur bands; Kelvin Hughes HF antenna Tuner, Screen voltage supply and HT timer; faulty spare Marconi Oceanic receiver to test some PSU mods before installing the mods on the good working one; tons of do***entation and interpretations to update. Not to mention my own projects - so I won’t be bored!
Now focus! Kelvin Hughes! Back in 2016, when the equipment arrived at the Museum we soon had the Receive side: Main Receiver, Reserve Receiver and AutoAlarm working. Had to “borrow” the Synthesizer power supply from the Transmitter to get the Main receiver synthesizer working. An initial inspection of the Transmitter showed that some parts had been robbed from the IF/HF antenna tuner: some high voltage capacitors, the antenna loading coil, and antenna coupling capacitor. (see pictures). Over the last three years I’ve collected together suitable replacements as and when I’ve stumbled across them at rallies etc. The pictures show where the missing parts go, and the replacements fitted.
The antenna loading coil was wound onto a length of perspex tube that I happened to have at just the right diameter. Paul (Museum Curator) machined a shallow spiral groove into it to keep the winding in place. (Pictures)
The coil tappings and capacitors are not yet connected as these are dependant upon the antenna characteristics and will be decided during commissioning.
That’s as far as it goes on the HF tuner until I can get back on-site.
The next issue is the Power supply and it is a beast! 3 Phase to supply 3KV HT, 6V @ 10A for heater, 220V screen, 24 VDC for control circuits. I can barely lift it so probably shouldn’t. However, I found the screen supply sub chassis and the HT timer PCB hanging on by their wires and a couple of yellowed noted from an exercise book noting which coloured wires go where. The timer PCB has seen some abuse around its 15V regulator and why that 10K power resistor has been bridged with a flimsy white wire remains to be seen. I should be able to test both these units on the bench before refitting them to the PSU. (have to add PSU pics in next post)
Further update to follow in due course.

Michael (GW7BBY/GB2MOP)
 

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#22 · (Edited)
Welcome back onsite, Mr. Oceanspan... lovely to get another update from you. How you manage to sort out all that gear is beyond me. I can't imagine having the skills and patience necessary to do any of that, even though I'm the most patient man I know! Your tech know-how astounds me, although it probably shouldn't. I compare what you're doing to the somewhat rudimentary skillset I managed to accrue during my time at sea. I guess it was the communication side I found the most interesting, that, and the fault-finding work, especially on radar, though with modified joy when 'put on the shake':

"Sparkie.. can you come and have a look at the radar..." (Always in the small hours of the morning when in the Channel and in thick fog).

Or the more usual: "Hands off c*cks, on with socks; rise and shine, do your thing for Sugar Line!!!" (All ports/windows pushed as wide open as possible, all overhead lights on and stereo/radio - if any - switched on, max volume). Sleep through that lot and you deserved a medal of some sort.

Towel wrapped around waist, stumbling up to the pitch dark wheelhouse: "O.K. I've looked at it, it's still there, now I'm going back to bed.."

'Just happened' to have an acrylic cylinder available? Just the right size? Now that is a coincidence. Looks like someone is looking after you and the museum. And someone who could make machine spiralling grooves to take the coil windings? That's stretching the old 'coincidence' bit a little. I'm always amazed, how things come together like this.

Keep well. The lockdown will force us all to take another look at what we do in our lives. Best of luck with the Museum and the radio gear.

Best rgds, as ever, Paul
 
#23 ·
Thanks Paul, its good to hear your dulcet tones again! In way I'm sorry I missed all the fun of being at sea, maybe not so sure!
I've treasured that piece of acrylic tube for about 30 years and always knew it would be useful one day. I've still got about 18" of it left to go into a remote antenna coupling unit that I might actually finish if this lockdown lasts long enough.
Update to follow before too long.
Best regards - Michael.
 
#24 · (Edited)
Mr. Oceanspan!

Halloo from across the seven seas, and hope all is well. I am waiting for your next installment about the good works at the new home of Marconi Marine and its wondrous and beautiful equipment(s). That piece of acrylic tube... has it found its next usage yet? So many questions. I'm like a kid: "Daddy, please, can you tell me why the anode coupling on the Oceanspan isn't .... well.. . coupling anymore?" "Daddy, please (tugging on shirt) ... when are you going to let me play with the tuning dials on the 'Oceanic'...?" "Daddy! You promised me that you'd get those lovely old Nixie tubes working again on the Apollo... can it still pick up Portisheadradio, Bergen and Barbados...?"


It's no good, I just can't stand it anymore, living here in isolation... I've got to have news of progress!! (When you have a minute, gov... when you've got a minute to lay down your 'scope probe and AVO, time to look out the window and think of us poor Marconiless souls living down at the bottom of the world when you pick up your cup of cold coffee... It'll be like opening my Chrimbo presents again, tearing the coloured paper and pretty bow off your next missive, desperate and overly eager to devour the contents.

Seriously? Must 'ave more, gov., must 'ave more.

Best regards for spring and the coming summer weather.

Paul
 
#25 ·
Kelvin Hughes Progress

Hi Paul,

Things must be crook in the antipodes if you’re begging for posts. I was saving myself until I had a bit more to report. However, having been stung into action, I’ll do two posts, one on the Challenger and another, here, on the Kelvin Hughes. I mentioned PSU issues in a previous post, particularly the screen supply and start-up sequencer/Timer. When I tested the Screen supply on the bench it was only adjustable over 100 – 130VDC. It is supplied from a 250V tapping off the main transformer. One of the diodes in the rectifier bridge had failed, also one of the two 2N4240 was well below par, but not completely failed. Replacing the four rectifier diodes with a modern bridge rectifier and replacing both 2N4240s has fixed it. I now get the specified output of 200 – 250 VDC needed to set the nominal screen voltage at 230VDC. (Pic attached)
The timer/sequencer board operates at startup to delay application of HT until the heaters have been on for 3 minutes, or 1 minute standby to start. It had suffered severe overheating (Picture) at the left hand end where a poor little Zener had been struggling to drop 24+Volts to 15VDC. It also took out some of the tracks on the bottom of the board. I imagine some poor R/O bobbing around on the seven seas congratulating himself on replacing the Zener with the LM7815 regulator in the picture. The other Zener, a 5v one is also prone to overheating. I spent yesterday etching circuit boards for various projects including a small daughter PCB that picks up on the old Zener stud holes and uses a 7815 and a 7805 regulator with plenty of heatsinking. A benchtop lash-up established that all the logic circuits are working correctly but the relay just to the right of the burned section that is supposed to pull in the HT contactor is not making. It operates, but the contacts do not make. The heat has probably destroyed the tempering of the contact blades. I’ve found a supply of exact replacements from Poland and one is, hopefully, winging its way to me now.
The Kelvin Hughes synthesizers, one in the receiver and one in the transmitter, have a regulator board to provide + & -5V, +12 and +17VDC. I’ve got a handful of spares with faults. The lower voltages are OK, but the +17 rail seems to be a common failure. The regulator is an obscure IC: MC1461. They do turn up from time to time, but at very high price. Its expected to drop 37v to 17v, the current demand is not terribly high, but dropping 20Volts even for a couple of hundred milliamps still adds up to a few watts (4ish) to dissipate in an enclosed area with no heatsinking. So another of the little boards I’ve been etching is another daughter board to pick up on the MC1461 connections, but uses an LM317HV regulator with a decent heatsink. I’ll post a picture when I’ve assembled it.
The other PCBs include a revised over voltage clamp for the Marconi Oceanic. Oceanics seem to be prone to pass transistor failures: a single TO220 device on a heat sink to provide a lot of current at 5V for approx 100 TTL chips, display and various other functions. I’ve got the spare faulty Oceanic at home to experiment on. I’m planning to replace the TO220 device with a darlington TO3 device on a bigger heatsink. The TO3 device has much lower thermal resistance junction to case, bigger contact area with heatsink and better clamping force to heatsink. So fingers crossed! Just to make sure I’m adding a serious over-voltage clamp just to make sure.
The other circuit boards are a new Mic amp and mild speech processor for my home-built transceiver and an AM modulator. 35 years ago when I built this transceiver it was intended to be a multimode job but never got any further than SSB/CW. Now I’m getting involved with historic radio groups (VMARS in UK) AM would be useful so I can join in their nets.
Now go to the Challenger thread to read more!

All Best Regards – Michael.
 

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