Clarke & Smith

[Herald1360]

The IFTs will likely contain (fixed) capacitors anyway even if they are slug tuned.

[RichardGM]

Originally Posted by valves4amps

Here's another contribution I found lurking amongst my files a test manual.

Rgards
Dave

I realise the thread has moved on, but having just looked at that circuit I am interested to see the phase-splitter arrangement. A unity-gain inverting amplifier is a common use for an opamp but I don't think I've ever seen one like this in a valve audio amplifier.

[kalee20]

It's relatively common - the paraphase phase inverter. As an example, the Soundmirror tape recorder uses this type of phase inverter. Its advantage is it is self-balancing with the valve characteristics having a pretty small influence on equality of the two outputs.

[PaulR]

Be careful making any adjustments to the IFTs. I did this and the core disappeared into it.

[terry123]

I've seen a few of this particular model over the years. For some reason they quite often appear naked without the wooden case. Like all their schools kit they were not built for aesthetic purposes but to a strict supply contract spec that is why the C&S and early goodsell and Coomber schools kit appears in a similar utilitarian giuse. Dates to mid 50s use of differant valve types is typical, ECC83 had probably not long come onto the market replacing an ECC40. C&S did like EBC41s and the octal EBC33s in the 1st gen schools kit strapped as troide amplifiers! Must have had a shed load! Unfortunelty I cannot help with a circuit . 88/8/2 designation indicates an 8 watt amp and second , later model



If anyone wants a copy of the dyeline scans for the 88/12 I have now had these digitised from originals via a large format scanner and they are much clearer to read. Just let me know via PM with your email as the files are too large to post here.
Regards, Terry

[RichardGM]

Originally Posted by terry123

C&S did like EBC41s

That explains the otherwise puzzling feature of this receiver having two of them with the diodes in one unused.

[gostlow]

well, I've finished swapping out dubious components and switched on . . it receives much better than I'd hoped for [MW and LW only of course]

I was able to peak up the IF [465kHz] and align the tuning dial . . maybe revisit that

sadly the EM34 'magic eye' doesn't glow and replacements are prohibitively expensive [also a 'pig in a poke'] so I'll probably run without one [or strap a green LED to the envelope to 'look right' !]

ver 3 of my reverse engineered circuit is attached . . this is now pretty close

what a pity that 69% of the resistors begin '47' as it makes tracing so much harder . .

the 'On' indicator is a lens of soft red plastic through which the dial lamp shines . . at some point in the past it has been in contact with the bulb and is, to an extent, burned black . . if anyone knows of a replacement or a suitable fix then I'd be very pleased to hear from them

my first valve project for fifty years, it has been fun . .

[gostlow]

This photo doesn't quite do it justice, but the the 'new old stock' 6E5 is in, replacing the EM34 . . I couldn't get hold of a neat 6pin socket for the 6E5 and had to make do with some huge ceramic thing, but the 'magic eye' works and, to my mind, brings the radio to life.

[kalee20]

Lovely!

[Techman]

Originally Posted by gostlow

but the 'magic eye' works and, to my mind, brings the radio to life.

Yes it does, but they don't stay like that for long. If you use the set every day for hours at a time, you'll see it gradually lose its brightness over a few months.

[Radio Wrangler]

You might want to add a hidden switch round the back to give it a magic eye conserving mode.

David