component ID help

Dave McGuire

unread,

Jul 23, 2023, 7:04:23 PM7/23/23

to

Hi folks, I'm looking to identify what I think is a transistor, in a
TO-72 package (TO-18 with four leads), in an old Victoreen radiation
survey meter. The number is "ITS 30487". It's also marked "7736" which
I assume is a date code.

Can anyone tell me what this is?

Thanks,
-Dave

--
Dave McGuire, President/Curator
Large Scale Systems Museum
New Kensington, PA

Phil Hobbs

unread,

Jul 23, 2023, 11:50:44 PM7/23/23

to

On 2023-07-23 19:04, Dave McGuire wrote:
>
> Hi folks, I'm looking to identify what I think is a transistor, in a
> TO-72 package (TO-18 with four leads), in an old Victoreen radiation
> survey meter. The number is "ITS 30487". It's also marked "7736" which
> I assume is a date code.
>
> Can anyone tell me what this is?
>
> Thanks,
> -Dave
>

Probably an internal part number. BITD transistors were commonly marked
with customer part numbers. (Around 1982, I was working in a group of
RF engineers, and a lot of the parts available for us to use had cryptic
part numbers like that.

I assume that one of the leads is connected to the case (the usual
situation).

If it's the front end of a proportional counter, it might be a FET such
as a 2N4117A JFET or a 3N163 MOSFET. For a Geiger counter, it would
probably be something a bit more robust such as a 2N2222.

If none of the leads is connected to the case, it could be something
less common, such as a dual-gate FET. I used to use a lot of 3N201s in
that package.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

Michael Terrell

unread,

Jul 24, 2023, 8:11:18 PM7/24/23

to

On Sunday, July 23, 2023 at 11:50:44 PM UTC-4, Phil Hobbs wrote:
>
> If none of the leads is connected to the case, it could be something
> less common, such as a dual-gate FET. I used to use a lot of 3N201s in
> that package.

I used to replace a lot of 40763 dual gate Field Effect transistors in garage door openers. I was doing the for a friend with a garage door business as a sideline. A nice part, but they didn't like nearby lightning strikes.

whit3rd

unread,

Jul 24, 2023, 9:24:15 PM7/24/23

to

On Sunday, July 23, 2023 at 4:04:23 PM UTC-7, Dave McGuire wrote:
> Hi folks, I'm looking to identify what I think is a transistor, in a
> TO-72 package (TO-18 with four leads), in an old Victoreen radiation
> survey meter. The number is "ITS 30487". It's also marked "7736" which
> I assume is a date code.

Hard to be sure, but Siliconix was making PFET junction FET discretes with that
package, like this one

[archiveorg bitsavers_siliconixdixLowPowerDiscretesDataBook_42980376 width=560 height=384 frameborder=0 webkitallowfullscreen=true mozallowfullscreen=true]

see page 120, 2N4867 series

If that's your item, pin 4 is the case (just a shield, not diode-connected to anything).
There might be a S embossed on the can...

Phil Hobbs

unread,

Jul 25, 2023, 4:51:09 PM7/25/23

to

Coincidentally, I just bought a reel of BF998s, which are the last
remaining dual-gate MOSFETs, now LTB, alas.

I don't use a whole lot of them, but the amount of design space I've
been losing lately due to EOL parts is pissing me off.

The worst was the BFT92, which was almost ten times faster than the next
fastest remaining PNP (5 GHz vs 600 MHz-ish).