Talking AF117 etc

[stevehertz]

I have fixed an AF117 by tapping it fairly hard with a screwdriver handle.

Obviously in general RF terms I know what a 'screen' does. So, in this instance removing the screen connection must surely have some, theoretical or otherwise, affect on the performance of the radio? Yes? No?

[paulsherwin]

This particular construction seems to have been a Mullard thing. The AF11x series didn't have spectacular HF performance, and the screen wire may have been more about market positioning thsn anything else. I've replaced quite a few with unscreened types with no problems at all.

[G.Castle]

Originally Posted by paulsherwin

The Dutch ones do have a better reputation in this respect, but there seems to be a lot of variation generally. Not all the UK made AF117s have developed shorts (yet).

Does anyone know where the 'Bel' ones were made?

BEL transistors were made in India from about 1962

(Bharat Electronics Limited)

[paulsherwin]

Thanks for that, interesting.

[Vintage Engr]

BF 450's generally work quite well. But as Paul says, some experimentation may be necessary.

David.

[G6Tanuki]

Fascinating to hear that BEL Germanium transistors were from India.

I guess that - as a developing nation - it would have made sense for India to take on production of Germanium transistors, probably using licensed technology and maybe too Mullard manufacturing equipment to build its electronics industry as the likes of Mullard/ASM - faced with the emergence of Fairchild's overwhelmingly-superior Silicon Planar technology - were either moving to Silicon transistors or getting-out of the low-profit consumer semiconductor industry altogether.

History, Technology and Economics are always interestingly interwound.

[wireless_john]

I think I'll hang on to the BEL one that I've got and use it if I haven't got anything else. That's in the hope that it might not suffer the tin whisker effect like the Mullard ones do!

John

[Maarten]

Originally Posted by Techman

Yes John, I've still got the back off and looking with the magnifying glass I can read on one "Mullard AF115 Made In Holland 2+P", The other that I can partially read is an AF117 and seems to also be made in Holland, the third I can't see its markings on without bending it about (which I'm not going to do), but expect it to be the same.

Your AF115 and an AF117 in oldjohn's radio both seem to have date/batch code 2+P. This might have to do something with it as well, as it seems that Made in Holland isn't the only criterion - they do fail over here as well, thought those could be imports, I suppose.

[Paul_A_R]

Bharat Electronics Limited was set up in 1954 under the Ministry of Defence and the Indian military appears to still be their largest customer. They still make some TO3 type transistors for non military use.

[Maarten]

I think they also produced Philips valves back in the days.

[VT FUSE]

There was a largely unacknowledged electronics industry in India, we bought lots of Sonar Buoys made there and Mullard sourced plenty of valves produced, boxes carry IEC legend, they also made Transistors.
Mike