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Old 29th Jan 2023, 6:30 pm   #1
Bri8691
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Default Grayshaw SG50 signal generator

Hello!

I have bought a Grayshaw SG50 signal generator - and there seems to be very little info online!
It has 2 tubes in it - a 8D3 6AM6 - (which I found online) and another just marked ā€˜4E4ā€™ (which i can find nothing about..) Iā€™m very new to this - so any help / info on the 4E4 much appreciated.

Thank you,

Brian
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Old 29th Jan 2023, 7:22 pm   #2
ms660
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Default Re: Grayshaw SG50 signal generator

From an old advert, two Z77's.

Lawrence.
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Old 29th Jan 2023, 7:45 pm   #3
Cobaltblue
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Default Re: Grayshaw SG50 signal generator

The only 4E4 i can find has a CT base.

https://www.radiomuseum.org/tubes/tube_4e4.html

It would be an odd choice any chance of aome pictures of the inside of the genny?

Cheers

Mike T
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Old 30th Jan 2023, 6:00 pm   #4
Bri8691
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Default Re: Grayshaw SG50 signal generator

Thanks ms660, I see the 8D3 6AM6 is the equivalent of a Z77 - the '4E4' is strange one - perhaps its a red herring, and the ID legend is missing somehow? although i assumed it would be etched into the glass..?

Thanks for the info Lawrence!

Quite by coincidence, I visited L.F. Hanny's shop in Bath, a few times in the 80's!!
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Old 30th Jan 2023, 10:43 pm   #5
Lucien Nunes
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Default Re: Grayshaw SG50 signal generator

That is more like a date / batch code, not a valve type. Its position and appearance are typical of a Brimar date and it decodes as week 4, May 1954 / 64, but would often be followed by a slash and another number that can be decoded to a valve type. But in any case, people can often identify the valve from its internal construction.
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