Vintage transistor ? - UK Vintage Radio Repair and Restoration Discussion Forum

Jolly 7 · 21st Nov 2018, 9:40 pm

Here's a tiny device that came out of an old radio. It looks like a transistor but has no markings on it. The circuit board it was soldered to is broken and was given to me to play with. Any idea as to its identity please ? The board also has two BF495 transistors and a number of coils.

HamishBoxer · 21st Nov 2018, 9:42 pm

Certainly a transistor ,why do I think BF947??

Maarten · 21st Nov 2018, 9:52 pm

It is certainly an HF transistor. Could be either germanium or silicium. I think the yellow colour coding can be found somewhere in some data sheet, but which? The best way to find out, is to look up a schematic for the set it came out of. I hope you wrote down the make and model. Or else the printing on the PCB's may give someone a hint.

Jolly 7 · 21st Nov 2018, 9:52 pm

And here's the PCB I desoldered it from.

G6Tanuki · 21st Nov 2018, 10:01 pm

The board looks like some sort of VHF preamp or tuner.

Jolly 7 · 21st Nov 2018, 10:05 pm

My best guess is that it may have come out of a Roberts radio, but I don't have any other bits from the radio. It looks a bit like a Mullard module to me, the ones that have the hairy AF117s on them.

Radio Wrangler · 21st Nov 2018, 10:14 pm

Or BFR90 or all sorts of UHF transistors. Even some MMICs went in that sort of package. 1980s onwards. Not very vintage.

David

turretslug · 22nd Nov 2018, 12:52 am

Those "pill" packages with yellow or green paint used to feature in things like ELC1043 tuners- perhaps there was a grading for RF or mix/osc duty as with previous transistor series. Once something with sufficient performance for the top of Band V was being churned out in swarms, they might have had a low enough unit price to percolate down to less demanding use like the above.

Skywave · 22nd Nov 2018, 1:24 am

That case is a TO-107: quite a rare package. 2N1561 and 2N1562 spring to mind: PNP germanium; VHF amplifier; Vce (max.) = 25v.; 250 mW Ptot; manufacturer = Motorola.

Al.

Maarten · 22nd Nov 2018, 7:22 pm

Quote:

Originally Posted by Jolly 7

And here's the PCB I desoldered it from.

Philips/Mullard for sure. Could you take a picture in which any numbers on the copper side are readable? Also, what are the date codes on the BF transistors? If it happens to be used in continental models there's a chance I can find something. Other people might have Mullard schematics in case it's a British design. I would date it on first sight mid to late 1970's, so chances are the transistor is a silicium NPN type or possibly a MOSFET. In older RF modules, especially for TV, germanium PNP types with this casing were used. You could use the diode setting on your meter to determine the polarity and the material.

NickG0HIK · 22nd Nov 2018, 8:19 pm

Maybe something like a BFR90, used as a front end.

https://www.digchip.com/datasheets/p...BFR90A-pdf.php

Nick

21st Nov 2018, 9:40 pm	#1
Jolly 7 Octode Join Date: Feb 2018 Location: Southampton, Hampshire, UK. Posts: 1,061	Vintage transistor ? Here's a tiny device that came out of an old radio. It looks like a transistor but has no markings on it. The circuit board it was soldered to is broken and was given to me to play with. Any idea as to its identity please ? The board also has two BF495 transistors and a number of coils. Attached Thumbnails

21st Nov 2018, 9:42 pm	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Vintage transistor ? Certainly a transistor ,why do I think BF947?? __________________ G8JET BVWS Archivist and Member V.M.A.R.S

21st Nov 2018, 9:52 pm	#3
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Vintage transistor ? It is certainly an HF transistor. Could be either germanium or silicium. I think the yellow colour coding can be found somewhere in some data sheet, but which? The best way to find out, is to look up a schematic for the set it came out of. I hope you wrote down the make and model. Or else the printing on the PCB's may give someone a hint.

21st Nov 2018, 9:52 pm	#4
Jolly 7 Octode Join Date: Feb 2018 Location: Southampton, Hampshire, UK. Posts: 1,061	Re: Vintage transistor ? And here's the PCB I desoldered it from. Attached Thumbnails

21st Nov 2018, 10:01 pm	#5
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Vintage transistor ? The board looks like some sort of VHF preamp or tuner.

21st Nov 2018, 10:05 pm	#6
Jolly 7 Octode Join Date: Feb 2018 Location: Southampton, Hampshire, UK. Posts: 1,061	Re: Vintage transistor ? My best guess is that it may have come out of a Roberts radio, but I don't have any other bits from the radio. It looks a bit like a Mullard module to me, the ones that have the hairy AF117s on them.

21st Nov 2018, 10:14 pm	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: Vintage transistor ? Or BFR90 or all sorts of UHF transistors. Even some MMICs went in that sort of package. 1980s onwards. Not very vintage. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

22nd Nov 2018, 12:52 am	#8
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,396	Re: Vintage transistor ? Those "pill" packages with yellow or green paint used to feature in things like ELC1043 tuners- perhaps there was a grading for RF or mix/osc duty as with previous transistor series. Once something with sufficient performance for the top of Band V was being churned out in swarms, they might have had a low enough unit price to percolate down to less demanding use like the above.

22nd Nov 2018, 1:24 am	#9
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Vintage transistor ? That case is a TO-107: quite a rare package. 2N1561 and 2N1562 spring to mind: PNP germanium; VHF amplifier; Vce (max.) = 25v.; 250 mW Ptot; manufacturer = Motorola. Al.

22nd Nov 2018, 8:19 pm	#11
NickG0HIK Hexode Join Date: Jul 2010 Location: Ireleth-in-Furness, Cumbria, UK. Posts: 286	Re: Vintage transistor ? Maybe something like a BFR90, used as a front end. https://www.digchip.com/datasheets/p...BFR90A-pdf.php Nick