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[burakkucat]

A while ago, I saw an item offered for sale which was described as an ex-GPO tester. As I have a liking for old test equipment, I splashed out £1-04 and purchased it.

Upon arrival, I gave it a good clean and checked it over. Very impressed with the discrete components and the quality of its construction. Needless to say, it is in excellent working condition. I estimate that it dates from the 1960s and was built to a standard that far surpasses current manufacturing standards.

For whom was it manufactured? I'm not too sure whether it was the GPO, Post Office Telecommunications or the BBC. I envisage that it would have been used by a member of the engineering staff of one of those bodies when configuring a land-line for an outside broadcast.

Does anyone recognise it or have an opinion, please? (I'm on the look-out for a copy of its Handbook, No. TP64.)

[attachment deleted by admin]

[sevenlayermuddle]

Not sure if this is any help,  but one thing that might narrow down its vintage would be to determine if the transistors are germanium or silicon.  Germanium transistors were of course gradually spuerceded by silicon.  I'm not sure of timescales and may stand corrected but if it contains germanium transistors I'd say it's likely to be of 60s origin.   If silicon, then early to mid 70s onwards would be more likely.

There's probably many wikipedia pages describing transistor names, but as I recall Mullard and other major European manufactures of 60's/70s devices, had a convention whereby germanium transistors began with an 'A', silicon with a 'B'.    Japanese transistors  tended to use a different scheme, commencing with a number and a letter, such as 2N....., but I'm betting your tester will contain devices with the european markings, thus making germanium/silicon easy to distinguish.

[burakkucat]

Thank you for that advice, 7LM. I have now made a note, on my ToDo list, to examine and document the semiconductor devices within that Level Measuring Set.

Regarding semiconductor devices, the only one that I recall by part number is an OC71. I have vague memories of BCxxx and 2Nxxx devices but valves were really the devices of my earliest electronic experiences. 

[sevenlayermuddle]

Ah, I also remember OC71's.   Some specimens were glass with a rubber sleeve and, if you peeled off the rubber sleeve, you could experiment with them as photo transistors.

But I feel bad now, as I said they all began with either 'A' or 'B'.  Ooops 

The document in front of me when I composed that was  a rather fragile, small orange pocket book that was once once on my Christmas list as a child,  entitled "MULLARD DATA BOOK 1970" (priced at a reasonable 4/- (20p )).  If I'd turned over the page, and if the pages hadn't cracked, from page 9 'SEMICONDUCTOR DEVICE TYPE NOMENCLATURE SYSTEM' to page 10 'OLD SYSTEM', I'd have remembered...

O = semiconductor, followed by..

A  = diode or rectifier
C  = transistor

 

[camallison]

You might find the handbook at http://www.telford-electronics.co.uk/manual.php?alpha=H  ... scroll down and it is listed as a Hatfield Instruments product.  Telford sell the manuals/handbooks.

Colin

[burakkucat]

Thank you for the link, Colin. I shall give that site a good examination, later today. (After I have been asleep . . . )

I'm not too sure where "Hatfield Instruments" fit into the "picture", for the device is marked "WAYNE KERR  WKC/1". 

Looking again at the image I have posted, I see that the manufacturer / model line (above the battery check buttons) has been lost in the shadow cast by the rubberised casing.

Anyone like to guess how I obtained that image?  No, not a camera nor a WebCam but by placing the device on a flat-bed scanner! 

[camallison]

On the Wayne Kerr info, the WKC/1 is described as "WKC 1: 20Hz-120kHz Measuring Set".  The Post Office (yes, that old) reference is possibly the original Hatfield reference.  I believe Hatfield Instruments were subsumed into the Wayne Kerr empire at some time.

I know it is a long shot, but you might be able to get a pdf of the manual from Wayne Kerr themselves by using their manual request form at http://www.waynekerrtest.com/asp/manualyourdetails.asp

Colin

[camallison]

Done a bit more digging in my old files - Hatfield Instruments Limited, based in Devon is now owned by JDSU!  Full circle!

Colin

[burakkucat]

Thank you for that updated information, Colin. You have provided me with sufficient details for some more detective work.

Now where did I put that "round tuit"? 

[camallison]

Now where did I put that "round tuit"? 

I've got one on my desk here - I rest my coffee cup on it!

Colin

[burakkucat]

It's time that I made an update to this thread.

Following on from Colin's suggestion, I contacted Wayne Kerr (the manufacturer) to see if they could help with the relevant documentation. A prompt reply, of the negative kind, was received. So on to Plan B. I made enquiries of Telford Electronics for the supply of the Product Manual, for the Hatfield Instruments device.

At the beginning of this month I realised that I had never had a reply from Telford Electronics.    So I sent a repeat of the e-mail and received, by return, a positive response. In exchange for a small "pocket money" sum, I possessed a copy of that manual before the week was out.

I attach scanned images of the front & back covers and of the first two printed pages. From the first page I obtain some more information:

"Post Office Specification RC 5816 (and addendum and corrigendum dated Jan. 1977)"

The second page, the History Sheet, gives the Post Office Approval Reference for the Manual which was first issued in July 1978.

The Wayne Kerr device (WKC/1) that I own is certainly from 10 - 15 years earlier. There are physical differences between the Wayne Kerr and Hatfield Instruments devices but the logic of operation is identical.

There is no urgency but I shall still continue to seek a copy of the Wayne Kerr Handbook No. TP64.

[burakkucat]

I continue in another post so that I can attach the two scanned images of the Hatfield Instruments device's circuit diagram, below.

There is (at least) one difference between my Wayne Kerr LMS 35A and the newer Hatfield Instruments LMS 35A. That is centred around the batteries test circuitry. I have two buttons to press, one for each battery, to check that they are able to deliver the requisite voltage, whereas with the Hatfield Instruments device that functionality has been built into the Input Level control.

Perhaps the circuit diagram will allow 7LM to reminisce on the subject of discrete semiconductor devices? 

[renluop]

I contacted Wayne Kerr (the manufacturer) to see if they could help with the relevant documentation. A prompt reply, of the negative kind, was received

'Tis obvious why you got a useless reply: the clue is in the name.

[kitz]

'Tis obvious why you got a useless reply: the clue is in the name.

Ive no idea what you mean

[Black Sheep]

Me neither. Would you be kind enough to go into a detailed explanation, renluop