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Old 9th Apr 2024, 9:55 pm   #1
mole42uk
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Default CV7370 transistors?

I’ve discovered that I have drawer full of CV7370 transistors. Gold plated metal cases, the ones I’ve tested report pnp, approx ß98, Uf323mV.

I haven’t been able to find an alternative type, can anyone help?
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Old 9th Apr 2024, 11:28 pm   #2
Rileyman
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Default Re: CV7370 transistors?

Possibly 2N501 ?
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Old 9th Apr 2024, 11:42 pm   #3
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Default Re: CV7370 transistors?

I had a look in Towers International Transistor Selector book and it suggests a 2N501 as an alternative. Checking the entry for the 2N501 then a AF124 is given as a sub. So probably useful to replace the AF11x series.

Is the CV7370 in a TO1 case like the AF11x range?

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Symon

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Old 10th Apr 2024, 7:14 am   #4
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Default Re: CV7370 transistors?

Oh, I never thought to look in Towers, I didn’t know the CV types were listed there. Yes, they’re TO-1 cases.
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Old 10th Apr 2024, 7:51 am   #5
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Default Re: CV7370 transistors?

The 2N501 was developed for military high reliability use, and "high speed computing at up to 20MHz"

Those were the days!

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Old 10th Apr 2024, 4:49 pm   #6
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Default Re: CV7370 transistors?

Here's what they look like:
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Old 10th Apr 2024, 5:02 pm   #7
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Default Re: CV7370 transistors?

That metal domed envelope with the flanghe-seam round the bottom is reminiscent of the transistors originally produced by Philco in the US and subsequently licensed to Plessey who made them in their millions at their plant in Swindon.

http://www.wylie.org.uk/technology/s...ics/Semics.htm

"Micro Alloy Diffused Transistors"....
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Old 10th Apr 2024, 10:39 pm   #8
Craig Sawyers
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Default Re: CV7370 transistors?

The original manufacturer and patent holder was indeed Philco. That patent on the MADT transistors must have still been in force if Plessy had to obtain a license to manufacture them in the UK.

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Old 11th Apr 2024, 9:28 pm   #9
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Default Re: CV7370 transistors?

A UK patent granted in the 1950's would normally have had a life of no longer than 16 years if all its annual renewal fees were paid. But there could also have been a licence in respect of know-how, for which the duration would have been determined by agreement between the two parties. Plessey regularly manufactured stuff under licence, and would have needed a licence under the US patent if they wanted to export stuff covered by a US patent into the US.
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Old 11th Apr 2024, 10:48 pm   #10
Craig Sawyers
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Default Re: CV7370 transistors?

American patent law is very different to the UK. Regardless of the priority date on the patent, an inventor can plead back to the date of actual invention. As an example, IBM used to have a legal notary stamp the pages of notebooks to enable that process to occur.

In any event, a company like Philco would have had the financial might to take out filings internationally, particularly on a key technology like MADT.

Whatever the ins and outs of the legal process, and any technology transfer package, the 2N501 was a bit of a landmark in Germanium transistors.

Germanium technology is still very much alive and kicking https://en.wikipedia.org/wiki/Silicon%E2%80%93germanium

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