Question about CV7007 transistor

[Fox Cunning]

Hello gents!

I hope some kind person can help me find any info regarding this transistor.
As you can see it is advertised as a Ge NPN, and as being the same as an OC77... but I thought the latter was a PNP!

Furthermore, I cannot find any datasheet, not even just terminals info anywhere.
So, does anyone know this mysterious CV7007?

Cheers!
Fox

[midwayfair]

It's PNP. They probably read "NTN" on the case and misunderstood.

[Fox Cunning]

Thanks a lot midwayfair!
Good call, that could have been the source of the misunderstanding.

In some old documents I've also found that 2N284A is mentioned as a replacement for CV7007, so it must be PnP.

[Arcane Analog]

For that price you can do much better at Small Bear and have the devices audited for you.

[Fox Cunning]

For that price you can do much better at Small Bear and have the devices audited for you.

No doubt, but they charge about £20+ for international shipping, plus it takes at least a week
The link above is for a capacitor made in Suffolk and ships in a day free of charge.

[Fox Cunning]

For that price you can do much better at Small Bear and have the devices audited for you.

No doubt, but they charge about £20+ for international shipping, plus it takes at least a week
The link above is for a capacitor made in Suffolk and ships in a day free of charge.

I meant transistor of course, not capacitor. Just noticed I can't edit my own posts

[Tony Forestiere]

Just noticed I can't edit my own posts

Sure you can. Hit the "Modify" button in the upper right of your recent post. (Sorry for the OT.)

[PRR]

Virtual Valve Museum has it as NPN, but other sites disagree.

RadioMuseum says it is the military version of 2N284A = OC77 and is PNP.
http://www.radiomuseum.org/tubes/tube_2n284a.html

Here's the best blow-up I can get of the CV7007 pin-out; also a OC77 pinout which "should" be the same?


Here is a very-vintage CV7007 datasheet which does not show pin-out but does clearly state "p-n-p", OC77 is the prototype (the base part from which mil-spec CV7007 was selected), and some distressing specs.
http://www.shinjo.info/frank/other/CVspecs/cv4-7a/CV7007.pdf

The most distressing number is 16dB noise figure. This is big hiss. and it makes sense: this part is specced for "switching", not for amplifying delicate music. A cynic would suspect that any part which was too hissy for OC77 uses, but otherwise healthy, might get tossed in the "switching CV7007" bin. OTOH germanium hiss is hit-or-miss, and they may have had enough low-hiss devices to fill CV7007 orders. But be prepared to try several devices for lowest hiss.

[Fox Cunning]

Thanks PRR! That was a very exhaustive answer.
I came across the Radio Museum myself yesterday after a long search, but couldn't find that datasheet (which is great, thanks a lot for that!).

In the end I couldn't resist: I bought one of those. Lightning fast delivery: it's here now!
There is a red dot to indicate the collector, and the base is the middle terminal - my multimiter confirmed that with hFE test.

I've put it on a breadboard and wow, does that amplify! Loudest thing I've every had. I've been very lucky because there was no hiss, just some very low hum probably due to the recycled components (mostly salvaged from power supplies) that I used for the rushed test circuit.

Now let's see if I can make something useful out of it!

[Fox Cunning]

Sure you can. Hit the "Modify" button in the upper right of your recent post. (Sorry for the OT.)

I must be blind Thanks!

[PRR]

> very low hum probably due to the recycled components

Can't blame the transistor. Or other parts. They do not know the tune. (50/60Hz isn't anything special to them.)

Hum most ALWAYS happens because our walls and rooms are full of power wires and devices. And we even run the pedal on wall-power (filtered, more-or-less). Hundreds of Volts of the stuff! Compared to 0.02V of precious guitar. Run on a battery a mile out in the woods, no hum.

You probably know this but there's always lurkers......

Hum on hay-wire test-rigs is because we don't try to put good shielding on them until we see if they work at all. Before performance we will box-up in grounded metal (or other technique) and test them for hum level.

Analogy: the seat in my air-cooled VW is wet. Why? Can't be the car, no water in it. Probably left it out in the rain, and didn't completely close it (top down, or leaky window seals).

[Fox Cunning]

Can't blame the transistor. Or other parts. They do not know the tune. (50/60Hz isn't anything special to them.)

Hum most ALWAYS happens because our walls and rooms are full of power wires and devices. And we even run the pedal on wall-power (filtered, more-or-less). Hundreds of Volts of the stuff! Compared to 0.02V of precious guitar. Run on a battery a mile out in the woods, no hum.

You probably know this but there's always lurkers......

Hum on hay-wire test-rigs is because we don't try to put good shielding on them until we see if they work at all. Before performance we will box-up in grounded metal (or other technique) and test them for hum level.

Thanks again, PRR. Yes, the whole thing being on a breadboard without any kind of shielding I presume does not help.