[Searcher2004]

Hi All,

I'm researching some marine radio equipment, a Coastal Radio Ltd 91/MX, probably of early 1950s era and have a question on the introduction of SSB for shipping use.

As ex-R/Os will know, basically up to the 1970s most 2 to 3 MHz ship to shore comms in the merchant and fishing sectors was done using AM. Towards the end of the 1960s there was a decision taken, particularly by the FCC in the US, to change to SSB. The details I have been able to Google say that no new licences for AM-only radios would be issued after 1st Jan 1970 and that after 1st Jan 1975 use of AM on the 2-3MHz band would be illegal.

The equipment I'm researching looks to have been modified by the makers to receive SSB, by upgrading the RF and mixer stages to more modern miniature valves and by the addition of a BFO, an AVC on/off switch and an RF gain control, so my question is - did the final regulations allow for a slow-changeover to the new mode by allowing the use of older receivers that could be modified to receive both AM and SSB?

73

[BobDixon]

I'm inclined to say the answer is "no". Radio equipment would require to meet the Type Approval requirements appropriate to the time. However that would not stop, within some limits, a radio exceeding the type approval standards. In particular a receiver might have a bfo for the resolution of cw signals in the df beacon band. It just happens that bfo could also be used to resolve ssb.

[Paul Braxton]

Often used the Marconi 'Atalanta' RX for SSB, as mentioned above, using the BFO in conjunction with the +/- 3kc/s fine tuning control to keep the intelligibility of the audio right during a call. The inherent slight 'wandering' of the older receiver could be obviated by doing that. Still doing just that, listening in to Ham bands.

[Searcher2004]

Thanks chaps,

I think the inclusion of a BFO probably does point to beacon reception and as you say SSB was a bonus. On another forum someone mentioned CONSOL reception but I think that was MCW?

Cheers
S2004

[david.hopcroft]

I don't remember exact dates when SSB came along, but 'I was there' at GKZ when equipment changes were made. Using DSB on MF RT afforded long range comms at night.

These are the DSB to SSB equipment changes. The big DSB transmitter - the W5 - was something like 10 feet long, and had all the WT and RT frequencies in use selectable from an operating consol. Huge great Geipel relays changed frequency etc. The little 'boxes' were single frequency transmitters with a power unit, drive and PA stage and were fed to a mast radiator via a combiner.


David
+

[spaarks]

1960's or early 1970's C&W Marine had Marconi NT201 SSB transmitters, paired with a Racal RA17.
I believe the NT201 was produced for the Royal Navy. Quiite a good TX for its day. The RA17 was a great RX, used Wadley Loop - very stable.
Don't think there was a legal requirement for an SSB receiver, though using the Atlanta was a pain on SSB due to drift.

Pix show installations on cs Recorder and cs Mercury. We later got ST1200/Redifon and Conqueror/Apollo respectively. The former was much better IMHO.

You'll see the big Grundig tape recorder in one of the photos. It was mainly used for playing an endless loop voice recording to keep the frequency occupied for long periods during cable splicing ops. Occasionally the Portishead op would give us free calls.

[david.hopcroft]

Those small craft users on yachts and such like who hardly ever used radio were of course not pleased when SSB became compulsory. However, they were still permitted to use 2182 on DSB for Distress purposes. You were allowed to summon help by whatever means. Every other crystal had to be removed from the set though.

David
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[Searcher2004]

Thanks for the photos, David and Sparks.

I took my amateur Morse Test at GKZ in June 1966 (and passed!). I think that the test was held in the/a transmitter room.

Yes, when I started going to sea in 1969 (as a Decca nav systems tech) there were a lot of AM-only sets on the older vessels we used for survey work and the various owners were very penny-pinching over new radio gear. In fact we usually carried a Pye SSB125T or 130 to make our own comms with the operators of the radio beacons we were using. We used 3631 and 3585kHz USB as working channels.

Cheers

S2004

[Tony Magon]

Hi Spaarks

Was in the Royal NZ Navy from 67 to 75 - The first frigate I was on was Otago/ZMSI - It had a couple of NT201's - RN numbered them as 640 - They were in a seperate tx room - and to QSY you had to walk from the Radio Office to the tx room and back again - This was if the other one was being used for something else - The main rx were RA17 - They could be used with a synthesiser or the normal tuning - We also have B40 and B41 rx - When working at ZLC Chatham Islands - 76, 83 and 85-86 the rx were Marconi Hydrus for the HF phone and telex link. The tx was a Radifon running about 300 w - The last Navy ship Canterbury/ZMCR that I was on in 71 - 73 used Marconi synthesised drivers and a couple of wide band MF/HF amps - The could run up to around 1000 to 1200w - In the finals they had either 14 or 16 4CX250B's in a series-parallel arrangement, so if a few of them died - the wideband amp would still keep running ok - In 75 - 89 worked for the NZPO at ZLB and ZLC then worked a VIS for a couple of year from 89 to 91

Tony VK2IC ex ZL4DE - ZL7DE

[david.hopcroft]

Searcher2004 - That would have been Angus Stark. He was OC when I arrived in 1968, but left to become Radio Surveyor in Hull. Hope he didn't find any 'illegal' crystals if he did a survey !!!

SSB freed up frequencies in the respect that the lower sideband could be used as a separate frequency. The Oil Rig RT and RTT private service at GKZ was an example. Tx was 3324 and Rx 3624 khz. Inverting the LSB into a double erect sideband made it possible to have RT on one sideband and RTT on the other.

David
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[Wismajorvik]

Originally Posted by david.hopcroft

Searcher2004 - That would have been Angus Stark. He was OC when I arrived in 1968, but left to become Radio Surveyor in Hull. Hope he didn't find any 'illegal' crystals if he did a survey !!!

SSB freed up frequencies in the respect that the lower sideband could be used as a separate frequency. The Oil Rig RT and RTT private service at GKZ was an example. Tx was 3324 and Rx 3624 khz. Inverting the LSB into a double erect sideband made it possible to have RT on one sideband and RTT on the other.

David
+

Stark was OC when I installed the inverted LSB unit after aligning and testing it at Redifon, Wandsworth. He was the examiner in Hull when I revalidated my ticket in ‘79.

[david.hopcroft]

Are these the ones ??

David

+

[King Ratt]

RFAs were equipped with Marconi NT204 transmitters aka Naval Type 640. First one I sailed with was in RFA Tidesurge in 1968. The maximum power output was about 750 watts to a whip antenna. Much use was made of A3J modes and both upper and lower sidebands . Good reliable transmitters.

[Wismajorvik]

Originally Posted by david.hopcroft

Are these the ones ??

David

+

For sure.

[david.hopcroft]

Found another DSB receiver used at GKZ. This one is dated December 1969. The Ops position behind was for what we called the ISB or Rig point which used the 'LSB' frequency. The Transmitters were Marconi HS113's although this 1969 dated view appears to show one as an H1000 wideband.

David
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[Ron Stringer]

That receiver in the console looks very similar to the MIMCo 'Mercury, receiver from the 1950s.

[BOB87]

I'm a Newbie to this site, but the Posts brought back sooo many happy memories. 4 of us,.. all R/O's with PMG Tickets, and strangers to each other, , were sent to Marconi Glasgow,..(Loan Quadrant I think), for two days training on the new SSB;.. we were then sent down to Portishead for two days to watch "how the other end works". All very informative and enjoyable... We stayed in the George Hotel, in Burnham-on-sea......all very pleasant...and so my next posting was to a ship, which had a 'Span 8 as the main tx,..lol:

[gwzm]

Hi Ron,

You're abolutely correct, the receiver in the console is a Marconi Mercury. I sailed with the Electra (HF) and Mercury (MF) receivers on several ships in the 60s. You can tell them apart because the Mercury didn't have the fine-tuning/bandspread arrangement of the Electra.
Happy days,
gwzm

[david.hopcroft]

Ron......I thought you might know more about the Transmitters. Both are wideband, but I was fairly sure there were 2 HS113's. There certainly were in later years. The unit far right was the drive unit.

On the consol behind the Mercury was a trial fitting of a Thrane & Thrane something. Noise was always a problem on 3mhz RT and this was an attempt at muting Rx when the landline spoke. It wasn't around long so perhaps not a success.

David
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[Ron Stringer]

The 'Mercury' receiver was succeeded by two generations of receiver on MIMCo ship stations: firstly the 1950s 'Atalanta' and then the 1960s 'Apollo'. Seems odd to be using it at a coast station in1969.

Don't know about the Marconi fixed station transmitters - found it hard enough to keep track of the marine ones.