Introducing the Clarke & Smith 747 schools receiver from 1966

[Nickthedentist]

When I was at primary school in London in the late 1970s/early 1980s, my school had a little oak-cased radio on a high shelf in the hall, feeding a matching column speaker. It was rarely used, the shiny silver Pioneer/Trio hifi being preferred by the younger teachers. But I admired its beautiful control panel hidden behind a lockable door, its chunky knobs, the lovely red glow of the pilot light and its big sound, and longed to get my hands on one.

I later found out that it was made by Clarke and Smith Mfg. Co. Ltd of Wallington in Surrey, thanks to this forum and to Terry Martini-Yates’ wonderful article in the BVWS about 10 years ago. I kept an eye on eBay, but they seemed very thin on the ground compared with their valved predecessors. I struck lucky last month though, and managed to get one for a very reasonable £26. It arrived quickly, well packed, and as the description said, it did nothing but hiss. It was surprisingly heavy for something so small.

These sets were made for educational use, apparently specifically for ILEA, the Inner London Education Authority, part of the now defunct GLC. This fact is screenprinted onto the back panel and branded into the bottom of the wooden cabinet sleeve, presumably to deter theft. Mine even had an ILEA-marked MK Toughplug – these were mandatory in London schools during my time there.

The front is plain, with just a small grille over the diminutive Fane speaker (for monitoring purposes only), a wirewound level control for the latter, and a red pilot light.

Behind the door is the control panel, which is bronze-painted steel with white lettering, with military-style Bakelite knobs having brass inserts attached securely to the shafts by two hex-headed grub screws. The volume control is a ten-position stepped attenuator, and gram and mic inputs can also be selected. There is no continuous tuning, rather, a three-position switch selects Home, Light or Third. Removal of a screw allows a little shutter to be rotated, to reveal the three adjustments for tuning. Care needs to be exercised in doing this as movement of the shutter tends to scratch the panel’s paintwork, and the adjusters can be screwed-in beyond the extent of their threads, which requires a fair bit of dismantling to rectify!

Round the back is a touchproof Belling-Lee L1722A/S socket for the 100V line audio output (centre tapped to earth), a 75-Ohm FM aerial input, as well as the captive 3-core mains input lead.

On the right hand side are the auxillary audio inputs via PO “Type B” jacks, and a BS546, 3-pin, 2A mains outlet. There is also a hole to adjust the tuner with a screwdriver, which (I think) coarsely sets the preset tuning.

[Nickthedentist]

After removing 4 screws from the underside, the wooden cabinet sleeve can be slid off, revealing a densely-packed chassis, with the power supply bolted to one side.

The latter is comprises an isolating stepdown transformer with a centre-tapped secondary, a couple of diodes providing full-wave rectification, two electrolytic caps and a couple of resistors. There is a separate winding for the pilot light, and two of the tags are used as termination point for the monitor speaker connections.

Thoughtfully, the chassis can be opened-up around a piano hinge running along the bottom front edge, leaving a bare metal base with the power amp and its 100V line output transformer, and a 3-sided frame supporting everything else. Construction is very modular, a lot of interconnections being made with push-on blade connectors.

[Nickthedentist]

The FM front end and IF panel seem to have been bought-in from West Germany. The tuner, with its 3 presets, is a Gorler 312-0032 and the IF panel a Gorler 322-0015.

[Nickthedentist]

The other sections seem to have been designed in-house by C&S:

The big PCB just behind the front panel is the pre-amp and is numbered “747.5”. The transistor line-up is
VT1 = OC71
VT2 = BC108
VT3 = OC44
VT4 = OC44

The smaller PCB at the back, on its own subchassis/heatsink is the power amp, “747.3”, with transistors:
VT5 = OC44
VT6 = OC81
VT7 = OC81Z
VT8 = AC127Z
VT9&10 = AD149

[Nickthedentist]

Build quality is pretty good, but not quite up to the standards of contemporary Hacker products, or earlier C&S gear. In my example, the lack of audio was simply caused by force on one of the push-on connectors having ripped part of a track off the power amp PCB. Intermittent cutting out seems to have been solved by cleaning and exercising the preset on the same board. The output transistors seem to have been replaced, probably in 1974 judging by the engraving on the back panel. There is also a lot of potential for wires to become trapped when the chassis sections are hinged closed prior to re-casing.

Luckily, the huge PAT labels which had been slapped onto one side came off easily with some Servisol Label Remover and an old bank card, and the cabinet looked OK after a few applications of clear furniture wax.

The radio is a delight to operate, and brings back a lot of fond memories of school assemblies. It’s sensitive enough to work with the most basic of aerials, and I have high hopes for its sound quality when I finally get hold of a 100V line transformer so that I can connect it to a decent-sized speaker and ask it to supply the 10W of which it’s capable. All being well, it will have pride of place in my little workshop.

Considering all the changes that have happened in schools and in audio technology since the mid-60s, some of these little sets appear to have remained in use for a surprisingly long time. For exmple, mine had PAT sticker on it dated 2005, suggesting that it was still in use some 40 years after it was manufactured. Another 747 sold on eBay some years ago had a repair sticker with an 0181- phone number on it, so was presumably deemed still worthy of repair in the late 1990s.

I'm also surprised they passed PAT tests, as the 2A outlet is not shuttered, the mains flex has the pre-1970 colour coding (I know this is a point of debate) and some of the internal clearances between live parts and others is minimal.

If anyone has a circuit diagram or any other service data, please do get in touch, as I would love to have a copy (as would Terry).

Radiomuseum.org does not have any details of this model, so I intend to make details of this set my first ever contribution.

[stevehertz]

Very nice. Glad you found it after all this while. Everything comes to he who waits.

[Nickthedentist]

Yes, 35 years but it was worth it.

[barrymagrec]

Back in the seventies I worked with someone who had previously been at Clarke & Smith and their service manager lived next door to my parents for many years.

[Nickthedentist]

That's interesting, Barry, where was that?

I grew up in Wandsworth, going to school in Earlsfield then Wimbledon.

[barrymagrec]

We lived in Old Coulsdon (my Father still does) - The company I was working for at the time was Leevers Rich in Trinity Road SW 18.

[Richard_FM]

Very interesting Nick, I'm not that familiar with Clarke & Smith, at least compared to the other Schools audio supplier Coomber.

It looks most like a piece of scientific equipment, & solidly made as they were expecting a few knocks & bangs when being lugged between classrooms.

Did it need much work to get it going?

I wonder if there were some later versions with the station legends changed to Radio 2-4.

[chriswood1900]

Nick well done for preserving a piece of audio heritage. At my time in school in Gloucestershire in the 60s I remember the lessons where C&S equipment was used particularly music and schools broadcast with fondness.
I love the history of these once famous manufacturers and remember enjoying Terry's article in the journal, it is pity more wasn't done to preserve the history. At least your radio has a discernible circuit which you can understand and not some anonymous chip with the numbers ground off!

[Nickthedentist]

Originally Posted by barrymagrec

We lived in Old Coulsdon (my Father still does) - The company I was working for at the time was Leevers Rich in Trinity Road SW 18.

I see that Leevers Rich were just along from the County Arms. My dad spent a lot of time there

Our school was just round the corner, at the bottom of Magdalen Road (the one with the Mobil filling station on the corner), on the other side of the road from Earlsfield station.

This particular set was apparently from a school in Greenwich.

[Nickthedentist]

Originally Posted by Richard_FM

...It looks most like a piece of scientific equipment, & solidly made as they were expecting a few knocks & bangs when being lugged between classrooms.

Did it need much work to get it going?...

Yes, the controls do look distinctly scientific.

It's small but not really meant to be portable - it has no carrying handle, for example. I think it was designed to sit in a safe, central location, and feed speaker(s) as required around the school. Our school had 3-pin Belling Lee outlets and C&S speakers above the blackboard in each classroom, but none were ever used while I was there.

No, all it needed was a quick repair to the AF input track on the power amp PCB. Even the controls were all crackle-free.

[Nickthedentist]

Originally Posted by chriswood1900

Nick well done for preserving a piece of audio heritage. At my time in school in Gloucestershire in the 60s I remember the lessons where C&S equipment was used particularly music and schools broadcast with fondness.
I love the history of these once famous manufacturers and remember enjoying Terry's article in the journal, it is pity more wasn't done to preserve the history. At least your radio has a discernible circuit which you can understand and not some anonymous chip with the numbers ground off!

Thanks Chris. The memories mean a lot to me too.

Yes, even without a circuit diagram, it's easy enough to work out what's going on where, and why.

[barrymagrec]

Originally Posted by Nickthedentist

I see that Leevers Rich were just along from the County Arms. My dad spent a lot of time there

I spent a lot of lunchtimes in the County Arms - and a good few evenings.....

[Richard_FM]

Originally Posted by Nickthedentist

Yes, the controls do look distinctly scientific.

It's small but not really meant to be portable - it has no carrying handle, for example. I think it was designed to sit in a safe, central location, and feed speaker(s) as required around the school. Our school had 3-pin Belling Lee outlets and C&S speakers above the blackboard in each classroom, but none were ever used while I was there.

No, all it needed was a quick repair to the AF input track on the power amp PCB. Even the controls were all crackle-free.

OK I see, at one of the schools I went to there was an odd socket on one of the classroom walls with 3 round holes. I assumed at the time it was an old electrical socket, but it could have been for some sort of radio connection.

I think ILEA had some sort of cable radio system for broadcasting schools programming they made themselves, I wonder if C&S made any equipment for it.

[Nickthedentist]

The sockets in our classroom were these Belling Lee ones (pic from eBay):

Good point about the cable distribution system, but I always thought that was TV rather than radio.

[1100 man]

Hi Nick,
Thanks for an interesting write up on an unusual piece of equipment. I rather like the C&S stuff, but I don't remember any of my schools having any radio gear. In fact, I don't recall ever listening to a radio broadcast at school!

Glad you have finally managed to find one!

All the best
Nick

[crackle]

Nice write up Nick.
I look forward to seeing your proposal for this radio in the Radio Museum.

Mike