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  #26  
Old 7th October 2019, 23:58
Paul Braxton Paul Braxton is online now  
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That's a nice-looking piece of kit, Michael. Takes me back. Glad you were able to at least temporarily sort the tripping problem. Might need to solder the IC's into the PCB, without the sockets, which as we all know, can give problems occasionally. Quite surprised that sockets for IC's were in use for sea-going equipment, come to think on it.

Thanks for the photos you post from time to time. Appreciate it.

Paul
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  #27  
Old 8th October 2019, 10:52
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Quote:
Originally Posted by Michael Oceanspan View Post
Andrew, I did tune it into the dummy load on 500KHz this morning, didn't try it on the antenna. Our Antenna will not be very efficient, its an inverted L, 45metres on the top section and 15 to 30 metres on the vertical part depending upon how high the mast is cranked up! However, the losses will probably be enough to keep it within legal limits!
Michael.
How's the earth system? That is the most important thing...
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  #28  
Old 8th October 2019, 10:56
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Originally Posted by Michael Oceanspan View Post
Our Antenna will not be very efficient, its an inverted L, 45metres on the top section and 15 to 30 metres on the vertical part depending upon how high the mast is cranked up!
Michael.

That's a hell of a lot better than the antennas presented by most new-builds in the 1990s when that transmitter came out!

Make sure you have good earthing and with that transmitter, the World's your oyster.
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  #29  
Old 8th October 2019, 11:40
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Yes, excellent work Michael.
They don't make transmitters like that any more, that is, something you can fault-find on and fix on the pcb. Those pcbs were laid out by draughtsmen with tape and pads, whereas I went straight to CAD in 1987 when I started my own business, and I abhor wiring soldered to boards.

UJ puzzled me for a while but you have lots of those in the museum. I call them flexible couplers.
73
Andrew
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  #30  
Old 9th October 2019, 23:39
Paul Braxton Paul Braxton is online now  
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Hang on! #18 : The Marconi 'Alert' receiver didn't have 24V capability, did it? My memory must be going a bit off. Just can't remember much about it now. Obviously you had the 'Salvor' on 24V but the receiver? Don't think so. In that case, did you have the capability of receiving anything at all without the ship's generator being operational? Anyway, the rude comments about the 'reserve' receivers stands. They were heaps of c..p! (In my humble; don't want to hurt anyone's feelings!)
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  #31  
Old 9th October 2019, 23:42
Paul Braxton Paul Braxton is online now  
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Michael: Just re-read your posting a few weeks back on the 'Oceanic' receiver, of which you have two at MOP. Now that set has all the IC's embedded firmly into the PCB, by the sound of it. Why didn't they do the same with the associated 'Challenger', I still find myself wondering. If you want the board fixed, just send it out here, along with all the IC's... love doing work like that. And for such a good cause!

Paul
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  #32  
Old 9th October 2019, 23:43
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Yes, the alert was the em rx, so it must have run from 24.

Junk, indeed...
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  #33  
Old 10th October 2019, 10:16
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Mike, last night about 2020 you were weak and unreadable in Penllergaer but I heard the loud and clear reports you were getting from Holland and France. By 2052 the ionosphere favoured you and I thought the quality of modulation perfect. A previous station with heavy AVC, clipping and filtering was unpleasant to copy, but no doubt effective in army communications.

As for the Alert, somebody remarked that switched on or off the result was the same. However, it met the specification for a watchkeeping receiver, and if ships used CW instead of MCW it had no chance. Auto Alarms were more sensitive. I often used the DF for 500 watch whilst away on HF.
73, Andrew
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  #34  
Old 10th October 2019, 11:12
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As has been said, the Alert operated from 24V and met the regulatory requirements (if maybe not the operational requirements) for a 500 kHz emergency and watch-keeping receiver. It was designed to receive MCW signals only, on the assumption that stations would comply with the the current ITU Radio Regulations requiring use of that type of signal on 500 kHz. Transmitters of the same era, such as Oceanspan, only produced MCW signals when 500 kHz was selected. Later designs would permit the operator optionally to select CW.

I was a firm believer that MCW was the mode to use for distress and safety calling and never used CW on 500 kHz - the purpose of a call was to attract attention so it made sense to me to make as much noise as possible! I believe auto-alarm receivers were not required by regulations to respond to CW and some designs did not.

So although the Alert was rubbish as a communications receiver, it could serve in emergency for communication with nearby ships involved in providing assistance to your ship when you were without mains power. That is the function required by the regulations.

Having said that, I much preferred to sail with Mercury/Electra rather than Atlanta/Alert since I was happier having two decent receivers for MF use than one excellent one teamed with a dud. When the ship's power went down, I still felt capable of dealing with things and keeping the radio room operating.
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  #35  
Old 10th October 2019, 21:25
Michael Oceanspan Michael Oceanspan is offline
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Challenger Transmitter Working - Replies.

A few of you have raised points about Challenger and associated equipment.
Andrew, I am pleased that you were able to listen in on VMARS on Wednesday evening, Conditions were atrocious, not just atmospheric noise, but adjacent stations overlapping our transmissions and tuning up nearby. However, it was a great pleasure to run the Challenger for an hour and to get some very encouraging reports. Oddly, and this applies to my home station in Llangeler as well, there are a number of stations in the Swansea and Merthyr area that are barely audible at the best of times, yet at the same time we have no trouble with the rest of the country or even northern Europe - geography I guess. Will we see you at the Crank-Up this weekend, Sat and Sun? ( I doubt I will be able to demonstrate the Challenger as with everything else running in the Museum, there won't be enough amps left for me!)
Earthing: At present it is earthed to the lattice mast, which is in turn well earthed. A good method I found with the Oceanspan was to connect the ground side to the tin roof covering the Radio and Telehone areas and about 10 metres or so below the horizontal part of the inverted L. I tried it briefly with the Challenger, but didn't seem to be any improvement. It is something to be addressed during the winter shutdown as there is scope to improve the antennas, in particular the receive side. We can get out far better than we can receive.
Paul: Oceanic and IC sockets. Most of the more common (cheaper?) ics in Challenger are in fact soldered directly to the boards. Only the bigger ones such as the 40 pin Divider and Synthsizer chips are in sockets and, guess what, these are the ones that cause problems! It is actually the same in the Oceanic: most ICs are soldered, but the processor, EEPROMs and a few larger chips are socketed. I might take you up on your offer and send you the Oceanic boards and a bucket-ful of TTL.
As you like my pictures so much, attached are left, right and top views of the RF unit.
Finally, I must mention that this project has only been successful through the generosity of EIMAC (now part of CPI) who actually donated the four 4CX350s to the project. The museum would have found it difficult to justify the cost of 1000.00 + worth of valves.
73 all - Michael.
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File Type: jpg RFUnitLeft_1LoRes.jpg (206.6 KB, 4 views)
File Type: jpg RFUnitRightSideLoRes.jpg (219.6 KB, 4 views)
File Type: jpg RFUnitTop_1LoRes.jpg (223.8 KB, 4 views)
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  #36  
Old 10th October 2019, 23:08
Paul Braxton Paul Braxton is online now  
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Bring it on! Very willing to help out with the boards. I worked for many years in various types of electronics factories, after I left the sea in '82, manufacturing equipment and doing lots and lots of PCB work, including the dreaded surface mount types. In fact, was still working at all this as recently as 2007, until we emigrated to NZ. Soldering in the 80-odd pin surface mount IC's by hand onto a brand new board was quite challenging (no pun intended). So the offer is a genuine one. Thanks for the photos as well, and taking the time out to reply to all these posts.

Best regards, Paul
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  #37  
Old 11th October 2019, 00:15
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Quote:
Originally Posted by Ron Stringer View Post
As has been said, the Alert operated from 24V and met the regulatory requirements (if maybe not the operational requirements) for a 500 kHz emergency and watch-keeping receiver. It was designed to receive MCW signals only, on the assumption that stations would comply with the the current ITU Radio Regulations requiring use of that type of signal on 500 kHz. Transmitters of the same era, such as Oceanspan, only produced MCW signals when 500 kHz was selected. Later designs would permit the operator optionally to select CW.

I was a firm believer that MCW was the mode to use for distress and safety calling and never used CW on 500 kHz - the purpose of a call was to attract attention so it made sense to me to make as much noise as possible! I believe auto-alarm receivers were not required by regulations to respond to CW and some designs did not.

So although the Alert was rubbish as a communications receiver, it could serve in emergency for communication with nearby ships involved in providing assistance to your ship when you were without mains power. That is the function required by the regulations.

Having said that, I much preferred to sail with Mercury/Electra rather than Atlanta/Alert since I was happier having two decent receivers for MF use than one excellent one teamed with a dud. When the ship's power went down, I still felt capable of dealing with things and keeping the radio room operating.
Hello Ron

I sailed a lot with the next generation of rx'ers: Apollo/Sentinel/Lifeguard N.

The Sentinel was good as a MF working rx, and I used the Lifeguard N (with BFO) as a 500 watchkeeping rx.

I was only thinking of your comments re main tx'ers not being powered from the emergency gene circuit the other day...what a great advantage that would have been - run the whole radio room on that circuit....

On my first ship, both rx'ers automatically switched to 24v if the mains failed....another excellent idea, way ahead of its time...

But, of course, typical parsimonious shipowners....and an IMO dominated by Panama and Liberia...
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  #38  
Old 11th October 2019, 01:37
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In my experience the radio room supply was from the Emergency switchboard. Not by regulation but pragmatism.
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  #39  
Old 11th October 2019, 07:13
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In my experience the radio room supply was from the Emergency switchboard. Not by regulation but pragmatism.
Problem was that the main tx often needed a 3 phase supply...
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  #40  
Old 11th October 2019, 08:51
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Problem was that the main tx often needed a 3 phase supply...
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.
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  #41  
Old 11th October 2019, 09:07
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Originally Posted by Ron Stringer View Post
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.
Fascinating, thanks.
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  #42  
Old 11th October 2019, 11:29
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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).
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  #43  
Old 10th December 2019, 19:58
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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
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  #44  
Old 11th December 2019, 01:34
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Quote:
Originally Posted by Ron Stringer View Post
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.
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...

Thank goodness I'm out of it.

/rant over.

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  #45  
Old 11th December 2019, 07:29
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Wonder if any of your 20th century camel committees gave a thought to this here.
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  #46  
Old 11th December 2019, 07:33
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Ha..nope....
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  #47  
Old 12th December 2019, 11:19
Michael Oceanspan Michael Oceanspan is offline
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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)
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  #48  
Old 12th December 2019, 13:16
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Hello Michael
I think you can label your speech inverter as "Privacy" equipment. Some passenger liners had that for AM, but an r/o could resolve it with judicious passband tuning and the BFO.

Latest project here is a homebrew 50w AM/CW valve vfo, buffer, PA rig with 5B/254s. I'm using it on the lower bands.
ATB, 73, Andrew
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  #49  
Old 12th December 2019, 13:30
Michael Oceanspan Michael Oceanspan is offline
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Yes Andrew, I believe the principle was used for the well known "Scrambler".
You, homebrew Tx sounds interesting, have to see if we can make an AM contact with the Oceanspan.

73 - Michael.
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  #50  
Old 25th December 2019, 01:20
Paul Braxton Paul Braxton is online now  
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Happy Christmas, Mr. Oceanspan!

Just wanted to thank you for the Challenger photo you posted recently. I've been unable to log in for a while, so could neither access the photo nor reply until today, when those nice people at SN have given me a new password.

Thanks for all your work with the iconic Mimco equipment this past year or so. I have been really pleased to know the 'Span, in particular has had a rebirth. And the Challenger project has really interested me as well. Well done indeed. I guess you'll have some time over the winter months to get some more work done while the museum is shut. Good luck with all that you do, and keep the photos coming in!

Wishing you and yours a great festive season and a healthy, prosperous and very happy 2020.

All the best, Paul
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