Marconi Challenger

I don't think I have been with an emergency supply that was not three phase although I had one with a battery supply which switched the three wire AC lighting into one two wire DC battery supply (not VG when fluorescent lights had been added to the lighting network!).

If you take the 'old' list of equipment that must be capable of being supplied from the emergency supply it is true that to some that meant 'only' the emergency supply - we had an amusing but expensive exhibition of how that, when applied to the rudder angle indicator, could precipitate excitments.

On more 'sophisticated' ships the reverse mistake was made. Anything is more secure if run from the emergency supply. But when, for instances running steering gear telemotor pumps from a supply not also capable of supplying the steering gear pumps themselves or when, similarly, supplying the thruster controls from the emergency supply then in both the possibility (actuality) of crippling the ship occurs in the event of an emergency supply (only) outage that would have otherwise left the vessel seaworthy. On the knockings of my career we also finally worked out why the standby generator would not start for the surveyor during a routine docking. The luboil priming pumps were fed from the emergency supply and the primed luboil pressure was interlocked with the start-up. The emergency generator was secured for surveys of its own again making outage of the emergency switchboard a potential 'fatal' single failure mode.

I am happy to say that current rules mean, in simple terms, that such essentials now 'find' an available supply if there is one.

In general terms three or single phase is decided by consumption but I would not like to rely on that criterion alone as lots of little loads might end up on one phase over time leading to unbalance. In the same way that houses are fed from alternate phase with neutral down the street (in an urban supply) unbalance is better avoided. I cannot immediately think of a 440V single phase load and to run the whatever from the domestic supply (main or emergency) usually introduces a set of transformers into the FMEA.

(Sorry - this is a hobby horse of mine, or was).

Hello Michael, Paul and others
I have been absent from SN for quite a while but finally decided to reset the password and login and I am very glad I did.
I was a MIMCo man probably because of their East Ham depot being just up the road from the college.
I have been fascinated by the exchange of messages and suffered quite a nostalgia hit recalling Commandants, Crusaders and Conquerors and even the Alert and Auto Key and the Monitor that was not much good as a reserve receiver but quite able at picking up AM stations as I recall when on route to ZSC.
I never came across the Challenger or associated equipment although I did have the Spector/Apollo on one ship.
I recall attending Glasgow depot attending a Crusader course the tutor whose name I don't recall had a favourite saying 'doom, gloom and despondency'.
Apart from a very short coastal voyage on the Thos Harrison's Defender/GTRT I never had the pleasure of serving with any of the Oceanspan series with the separate Mercury and Electra receivers or with the Atlanta.
My time being mostly Commandants and Crusaders with the Atlanta, Apollo and Nebula or that trusty Redifon R408 (?) something or other job.
Apart from one trip on the Denholm's Joya McCance/GPDA which had Swedish gear I didn't get my hands on a kilo watt transmitter before my one only experience with the Conqueror on the Texaco Rome/MSLJ.
I recall the Conqueror with Nebula being capable equipment that is until it suffered a fault in the power supply for which we carried no spares.
I managed to get a MSG to MIMCo HQ and my relief brought out the necessary items.
I spent many hours requesting QSP on 500 using the Reliance.
It was probably the rugged even basic build quality of Marconi equipment pre seventies that allowed us to keep things going.
I recall on the Texaco North America/GNEL transiting the Malacca Straits when the transmitter whip antenna on the funnel was struck by a lightening bolt which fried, frazzled or melted items in the Salvor, Monitor and other sundry gear in the ancillary rack, curiously the Auto Key was unaffected with just a few burnished contacts.
I managed to survive the bolt from the blue as it chose to go down the earthed reserve antenna switch route in the aerial box and not that for the main antenna which saved the Apollo and Crusader.
I remember quite a few happy weeks rebuilding everything with it all working when I paid off in the gulf thanks to sturdy Marconi kit.
I only came across more sophisticated equipment during my last few years at sea when on the Esso Mersey/GPUY which had Kelvin Hughes gear the main transmitter and receiver having synthesised units any frequency at the turn of switches.
Fortunately as I recall nothing failed as I might not have had much chance with the AVO and terminal screw driver although I managed to acquire an oscilloscope.
Thanks again Michael and others for the forum post and maybe there will be future instalments.
A visit to MOP will have to be done if only for another nostalgia fix and maybe even the chance to get personal once more with the Oceanspan as I am sure Michael you would be able to plant a few devilish faults much like the lecturers once did.
Hopefully I will catch GB2MOP or yourself Michael and QSO.
Many thanks
73's
de Rvator
M0ITR

Ron Stringer said:

Once I became technical manager at MIMCo I stopped all that 3-phase nonsense. It had never made sense to me - after all, the Crusader required less power than our kettle at home and we didn't have a 3-phase supply to the house. All new designs started for me had to be single phase devices capable of running from the ship's emergency generator supply. The Challenger, our most powerful transmitter was just the latest and last "traditional" (i.e. manually-tuned) design the company produced.

I suspect that MIMCo went down the 3-phase path accidentally, in the early days post-WW2, simply because design of their transmitters (and most other equipment) was carried out by engineers of Marconi Wireless Telegraphy - producers of high-power broadcasting, point-to-point and military transmitters. They were familiar with such techniques and would have felt happier using existing designs rather than starting from scratch. Big commercial organisations can resemble VLCCs in that it takes a lot of time and effort to turn them round once they have adopted a policy. MWT, with its inherent assumptions - that because they were the first, they were the best and could not be wrong - was an almost unstoppable force.

I failed to stop Conqueror being 3-phase but persistence made it the last of our transmitters to be designed that way. Everything from Commander onwards was single-phase but we still had little success in persuading many builders and owners of newbuilds to connect the radio room supply to the ship's emergency generator - they were even more difficult to convince than MWT. If it wasn't a regulatory requirement, it wasn't going to happen as far as they were concerned.

Click to expand...

Once I ascended the lofty heights (entered the sheltered workshop...) and became a Gov't radio regulator, I was continually annoyed at the parsimonious attitude of some shipowners re radio.

Running the radio room from the emergency generator (main tx power supply issues notwithstanding), and providing two main rx'ers that ran from mains and 24v would have cost absolutely SFA in the scheme of things, but would have provided so much more flexibility....as companies like P and O demonstrated...

Forget about the distress side (shipowners didn't care about that, in the main) - a more flexible radio room config would have meant improved company comms....but, oh no...

It took the execution of the R/O to make some shipowners spend money on proper comms.

Am I bitter and twisted.?....yes, but it is borne of direct experience with the IMO, et al.

The terrestrial side of GMDSS (DSC) is a debacle - a classic camel (horse designed by a committee).

Inmarsat C, COSPAS SARSAT and (much to the chagrin of Inmarsat and the UK) Iridium work well, and are a great improvement over 500.

Oh, and don't get me started on GMDSS Coast Radio Stations...(MAD)

Thank goodness I'm out of it.

/rant over.

Marconi Challenger - Rvator

Hello Rvator, nice to have you join the forum. Since the Challenger has been operational, there's not been a lot more to report, partly because the museum is closed for the winter and doesn't re-open until next Easter with a weekend crank-up. Also this is the time when maintenance, new displays and infrastructure changes can be done. As to the Challenger another reason for not using it much is that our 3 phase inverter is not quite up to the job and will trip out if I am not careful! The museum's electricity supply is right on the limit when the museum is open so this is another issue to be addressed over the winter. More interesting things: as it stands the challenger can only be used on 3.5Mhz and 1.8Mhz Amateur bands on USB, the higher amateur bands fall in the cracks between marine bands. I'm going to make a small modification to the band oscillator which generates the MHz component of the wanted frequency. It runs at between 41.7 and 66.7 MHz and is then mixed down to the required frequency. I shall pull the crystals out for the upper marine bands from 6MHz to 24MHz and use a DDS module controlled from an Arduino to inject the correct frequency for the higher amateur bands according to the band switch position.
The MHz component of the digital display is hard wired by diode or gates to the bandswitch so to get the correct digital display the diodes will have to be reconfigured. Nothing major and nothing irreversible.
For LSB operation I shall use a spectral inversion technique. A very interesting device was described in Practical Wireless in January this year. It is fitted in the microphone input and audio output and converts USB to LSB and vice-versa. When you think about it, the reason you can't resolve LSB with a receiver set to USB is that the carrier insertion is on the wrong side of the sideband resulting in unintelligible audio. With a clever bit of signal processing that a PIC processor can do, the audio spectrum is transposed to make it intelligible to a USB receiver. Conversely, if the transmit USB audio is transposed it can be resolved on a LSB receiver. Its not an unknown technique, but Ron Taylor (G4GXO) developed this PIC based device for users of commercial and military equipment which is usually limited to USB. If it is successful then I will make another unit for the Kelvin Hughes Zealand M-1250 transmitter which is my big winter project.
Finally, for Paul who like pictures, here is one of the challenger in action.

Best wishes to all - Michael (GW7BBY/GB2MOP)

Hi Paul, thanks for the festive greetings and apologies for not responding sooner. We have been away over Christmas and have just returned home. Over the winter shutdown I shall be modifying the Challenger for the higher amateur bands that fall in the cracks between the available marine bands, and will also add LSB capability.
The next big job will be the Kelvin Hughes Zealand M1250 transmitter (see picture). The receive side is working well, I've not yet tried the transmitter. I've provided a 3 phase supply, and the loom appears to be present to connect it to the console. We have all the manuals, the 4CX1500B is present but of unknown provenance, we also have a spare exciter also with its 4CX1500B present. I know a small PSU repair is needed. Hopefully it will soon be on the air, it is a 1.5KW transmitter, synthesized ( I don't think any mods will be needed for amateur bands, but will have to add LSB at some point) It provides for more modes than the Challenger: AM, ISB, DSB, USB, CW. However, before someone jumps on me, I'll be starting a new thread for this one shortly.
All best wishes to everyone for the New Year, we might even get to chat on the air!

Michael. (GW7BBY/GB2MOP)

Re Kelvin Hughes

Just a quick reply, before staring a new thread. Paul, the "jewellery" on the kelvin Hughes equipment is KH's take on control handles - its different and feels good to handle! (Pic Attached)
No, there are no Nixie tubes, just good old numbers printed on a disk to give a "digital" readout - see pic of M1250 Synthesizer and Receiver.
GURK was "RFA Orangeleaf" - another pic.
Troppo - nice to hear someone who sailed with KH Kit.
And Duncs, I've heard of NERA, in fact I think we have a cannibalised Nera ATU from I don't know what in our store. I'm not familiar with it.
OK Really going to start that new thread for KH.
Best wishes to all - Michael.