Murphy Radio Alarm Unit Type M.R.9380

[David Simpson]

Folks, Just been given this big 18" x 18" x 24" approx. cabinet. Seemingly some thumper of a Tx. Yet to open it, but dying to.
Any Murphy experts out there who can advise, please ?

Regards, David

[David Simpson]

Internal pictures this time. Seemingly used by electricity boards back in the 60's, in their sub stations.
Has 12 valves of the B7G/B9A type. Uses Jones plugs & sockets. I'm dying to find out more.

Regards, David

[HamishBoxer]

Some sort of monitor of the mains supply?

[AC/HL]

I'd guess it was for their telemetry or SCADA system.

[g8jzyian]

They were used in substations for if I remember correctly 4 alarms per S/S.
When an alarm happened it would close a contact to the 9380, The tx would be keyed on and a sequence of tones would be sent.First there was a pretone thent 3 groups which were the S/.S No. the the last group was the alarm No. .
The sequence was sent a few times per hour. Initially the decode was done by the control operator listening and counting the tones ; laterally there was a hard wired logic system that lit lamps in the control room.
That unit may well be on 106Mhz and may be the last one!!
If its on 86Mhz it it truly antedeluvian.

Regards

Ian

[David Simpson]

Well Ian, Good to get so much interesting info from an ex MANWEB(?) wacker. Ta La.
Seriously though, its a nice well built piece of equipment. Thankfully, no one had left a horrible battery inside, and there is just some slight rust patches inside the bottom of the steel cabinet which indicate electrolyte spillage at some time. So, need to find some documentation/manual/circuit diagram. A 12 core cable to a 8way Jones Plug/Socket connection is the main connector. Loss of a phase or two on 11 or 33KV ? Auto Recloser locked out after three tries ? A faulty Star/Delta T/F ? What would operate the alarm system back in the 60's, I wonder.

Regards, David

[g8jzyian]

Hi
Not MANWEB I was NOSHEB
To start with there were units that had only one alarm per S/S. When we had the luxury of 4 alarms I think that we had Trip Alarm, Battery Fault, Reclose Lockout, Sensitive Earth Fault. I'll have a word with someone who might have the blueprints. The metal box in the bottom should have the battery inverter for the radio.
I think that the TX had a QQV07/50. Does the label on the side of the radio hint at the frequency?

Ian

[AC/HL]

Originally Posted by g8jzyian

If its on 86Mhz it it truly antediluvian.

That's one of our specialities!

[g8jzyian]

Update
That vintage is on 86MHz and has 2 alarms, normally allocated as breaker trip and battery charger fail.
The pa is a QQV03-10 and th Tx operated from a 12v battery via the inverter.

Ian

[David Simpson]

Many thanks to Ian(a fellow NOSHEB guy) for all his info.
There are 5 pairs of motorized contacts. And, right enough - a fine wee 12V supplied St. Inverter.
86 or 106MHz, I'm dying to find out. I'll maybe de-rack the transceiver unit & lewk for crystals. Boy, am I glad to have saved it from the dreaded 'Skip'.

Regards, David

[David Simpson]

Now there are two !
The Murphy VHF Radiotelephones in both are TR821's which have a suffix 'RAU'.
I've acquired the Manuals for the R/T's Types MR806 & MR880/25, but not the TR821. Still hunting.
These cabinets are vaguely similar to the picture of the MR880, but have 12V St. Inverters, not mains supplied.

Regards, David

[David Simpson]

Removed the sub-units out of the r/h one - - a TR821(PA = QQV03-10), & a PU823(which uses two OC28's). According to a mod sheet at the back of the MR880/25's Manual - a TR821 = MR820.
Just two crystals, Tx = 12116.67
Rx = 12174.2 ( 86.3MHz written on it)
Is that 86 - ish MHz frequency used for any sort of comms these days ?
Also, is there a Murphy(Rank Industries) Museum out there anywhere ? Or perhaps a Murphy Radio Telephone Expert?

Regards, David

[Jon_G4MDC]

That's a bit weird. TX is likely x12 and so 72.7 MHz.
If RX is 86.3MHz as marked that is duplex split 13.6MHz.

Standard split was -13.5MHz with the Base TX high.
Many users of this freq segment back in the day. AA RAC.

The funny thing is 86.3Mhz was the start of the simplex band where TX and RX would be same frequency.

I suspect your RX may actually be 86.2MHz then duplex split is correct.
My list says 86.2/72.7 was AA Channel 11

I don't know the Murphy IF to calculate RX from crystal but I will try to find out.
Writing from the home of Murphy Radio (a garage across the road) I have interest in this.

[Jon_G4MDC]

Spot the mistake!! Please read x6 for TX not x12 above.
Finger trouble...

Any hint of the RX IF frequencies available?
12.1742 is probably also multiplied x6 for 73.0452MHz.

Then 1st IF is either

86.2-73.0452= 13.1548 which is mixed aqain with 12.1742 giving 2nd IF = 980.6 kHz

else it could be

86.3 -73.0452 = 13.2548 -12.1742 when 2nd iF would be 1080.6kHz

I don't know IF freqs favoured by Murphy but I expect this was long before 10.7MHz was standard as 1st IF!

[David Simpson]

Right enough Jon,
The writing on the crystal was a bit smudged, could've easily have been 86.2. I'll look in the 806 & 880 manuals and see if there is a common Rx IF frequency for their 800 series of R/T's.
I must admit to knowing sfa about Murphy R/T equipment. Pye - yes, a bit, as they were in common use in RAF vehicles for years. In fact, NOSHEB in later years changed their alarm system's R/T's to Pye Westminsters, I've been told.
Many thanks for taking an interest.

Regards, David

[Jon_G4MDC]

My pleasure David.
I was taught Morse code by a G3 who had one of those 821's on his shelf.
I don't remember it being used but it was probably on 70MHz knowing him.

Pye is my stronger suit too (trained with them in late70s-80s) but I like the local connection with Murphy. I think 86.2 and 980kHz 2nd IF is a good bet.

Best jon

[Jon_G4MDC]

Any further developments with this one a month on David?
I'm still curious about the 821

[David Simpson]

Nothing Jon, nothing. These thumping great units are just sat on a bench. The chap who gave me them still hasn't found the manuals. Nor has a contact at Scottish Hydro-Electric's HQ in Perth.
The Pye Museum has the Manual for the Murphy TR821 R/T, but it could be some time before it re-opens. Guess I'll just be patient. Would love to see & hear all those relays & tone switches going clickerty-clack someday.
I'm half way through repairing & renovating a Taylor 45B Valve Tester, and the Air Ministry Oscilloscope Type 11 is on its way to me this coming weekend. So I've plenty to get on with.

Regards, David

[Jon_G4MDC]

Very good. Patience is a virtue I suppose and at least you are not short on projects.
I look forward to the mystery of the RX IF lineup being cracked.
Jon