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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 20th May 2022, 1:11 pm   #1
g4aaw pete
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Default Unknown transistor osc.

Before I consider opening up this component & possibly destroying it, does anyone here have any knowledge of it?

Printed label reads 'quartz crystal controlled transistor oscillator type QC.93?, Frequency 1.5Mc/s made by Salford Elec.Insts.Ltd.'

It has a B9a valve base.
It was in a box of bits, so don't know what equipment it came from.
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Last edited by g4aaw pete; 20th May 2022 at 1:17 pm. Reason: extra info.
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Old 20th May 2022, 2:47 pm   #2
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Default Re: Unknown transistor osc.

Salford Electrical Instruments, a subsidiary of GEC were based in Times Mill Heywood Lancs. Now demolished and rebuilt as a Morrisons.

Their Quartz department made crystals from raw quartz, and the head of that department was Dave Standring, a very competent and amicable chap.

What's inside will be first class.

SEI also made ferrites and metal dust magnetic cores, film capacitors, the heated window antenna converter for Ford (patented!) and they made the 'Selectest' GEC's rather nice rival to the AVO 8.

QC is their normal prefix for crystal oscillators of all types. I no longer have their catalogues and spec sheets, sorry.

David
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Old 20th May 2022, 10:04 pm   #3
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Default Re: Unknown transistor osc.

Thanks for your info David. I hadn't come across them before.

Only pins 1 & 9 have any measurable resistance across them. I think a battery hung across those whilst checking 1.5Mhz on a mediumwave radio might be the only viable test I can try. All my bits & pieces are packed away pending a house move!
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Old 21st May 2022, 12:22 am   #4
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Default Re: Unknown transistor osc.

This looks to be the US patent for that oscillator, schematic included.
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Old 21st May 2022, 6:17 pm   #5
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Default Re: Unknown transistor osc.

Thanks for your comments & info Terry.

Curiosity got the better of me, & I connected a 9v battery between pin 1 & 9.
The unit draws 2.8mA & produces a heathy signal on 1.5Mhz

All I have to do now is find a use for it!
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Old 21st May 2022, 7:00 pm   #6
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Default Re: Unknown transistor osc.

SEI also made a range of "block" crystal-filters that were extensively used at the first-IF [10.7MHz] selectivity-blocks in Pye two-way radios [Cambridges, Vanguards, Westminsters, Europas] in days-past.

The designers of these filters really knew their stuff, and I would expect your 'encapsulated oscillator' to show similar levels of engineering excellence.
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Old 21st May 2022, 10:22 pm   #7
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Default Re: Unknown transistor osc.

Dave Standring's gang again. I've used a number of their crystal filters. These people were particularly skilled at designing fancy surface profiles to do 'energy trapping' crystals can behave as if they have an number of modes with very fine spacing in place of the more familiar ones. Oscillators can jump around within a group of such modes, leaving a little energy behind in the mode they left sometimes, and sometimes inheriting some in the mode they enter... the phase will have drifted. This results in the oddball fast phase jumps they can give, and which we sometimes see as phase noise. I learned a lot on my visits!

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Old 21st May 2022, 10:57 pm   #8
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Default Re: Unknown transistor osc.

A little bit of info on SEI here https://www.gracesguide.co.uk/Salfor...al_Instruments.

I too can think of a few locations where great engineering has been supplanted by supermarkets or similar. Plessey's Caswell Research centre seems very different now to what I recall in the 1970's http://www.caswellpark.co.uk/the-par...ers/index.html

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Old 22nd May 2022, 6:20 am   #9
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Default Re: Unknown transistor osc.

The first link came up with "server not found"

Roke Manor still seems to be a single research entity.

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Old 23rd May 2022, 1:08 pm   #10
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Default Re: Unknown transistor osc.

I visited Times Mill many times as they did stuff for the company I worked for. The patent they had was for just one aspect of the antenna amplifier, not the whole thing.

They also made some stuff for Amstrad satellite TV systems.

They then moved down to Portsmouth, to a GEC production facility. I don't think they lasted very long there, because the factory people decided they knew best, and customers didn't like it.
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Old 23rd May 2022, 3:34 pm   #11
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Default Re: Unknown transistor osc.

Quote:
Originally Posted by Radio Wrangler View Post
Roke Manor still seems to be a single research entity.
David
Where I work, Roke Manor Research (RMRL) often competes against us for contracts and it's been like this for decades. Sometimes they are a customer of ours as well. Sometimes it's a joint venture.
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