BF194/195 by Siemens any good - UK Vintage Radio Repair and Restoration Discussion Forum

cathy_vintage · 17th Sep 2016, 1:17 am

I have found a source of NOS BF194/195's branded Siemens at a reasonable price. Do these suffer failures due to internal corrosion like the Mullard/Philips ones please?

ms660 · 17th Sep 2016, 8:27 am

Can't speak for Siemens but the Mullard ones as you say give problems, search for "lockfit" on the forum, plenty of info.

Lawrence.

tony brady · 17th Sep 2016, 8:44 am

I think the Siemens should be ok in TO92 packages

60 oldjohn · 17th Sep 2016, 8:59 am

If they are Not Lockfit style I would risk it, I think it is the stress / strain transmitted through the thick legs. Over time cold flow of the plastic case causes minute movement inside case, causing failure. That's only my uninformed thoughts.

John.

Restoration73 · 17th Sep 2016, 9:05 am

TO92 package equivalent will be normally be marked BF494 or 495.

cathy_vintage · 17th Sep 2016, 9:17 am

Quote:

Originally Posted by Restoration73

TO92 package equivalent will be normally be marked BF494 or 495.

OK didn't realize there was the TO92 type. Should I buy these then? They are for the Mullard LP FM modules. Which is the most reliable manufacturer to go for?

tony brady · 17th Sep 2016, 9:43 am

Restoration73 is correct, I have used Philips BF494 in TO92 before . The Siemens data sheet shows them as lockfit cases.

paulsherwin · 17th Sep 2016, 9:55 am

The BF494/5s are difficult to find and pricey. Lots of other transistors will be fine as BF194/5 replacements in domestic radios.

All my Lockfit experience has been with Mullards. If Siemens used the same production process then they're likely to suffer the same problems. They may even have been made by Mullard under contract.

17th Sep 2016, 1:17 am	#1
cathy_vintage Pentode Join Date: Sep 2016 Location: Willerby, East Yorkshire, UK. Posts: 191	BF194/195 by Siemens any good I have found a source of NOS BF194/195's branded Siemens at a reasonable price. Do these suffer failures due to internal corrosion like the Mullard/Philips ones please?

17th Sep 2016, 8:27 am	#2
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: BF194/195 by Siemens any good Can't speak for Siemens but the Mullard ones as you say give problems, search for "lockfit" on the forum, plenty of info. Lawrence.

17th Sep 2016, 8:44 am	#3
tony brady Hexode Join Date: Mar 2014 Location: Peacehaven, East Sussex, UK. Posts: 278	Re: BF194/195 by Siemens any good I think the Siemens should be ok in TO92 packages

17th Sep 2016, 8:59 am	#4
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,987	Re: BF194/195 by Siemens any good If they are Not Lockfit style I would risk it, I think it is the stress / strain transmitted through the thick legs. Over time cold flow of the plastic case causes minute movement inside case, causing failure. That's only my uninformed thoughts. John.

17th Sep 2016, 9:05 am	#5
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: BF194/195 by Siemens any good TO92 package equivalent will be normally be marked BF494 or 495.

17th Sep 2016, 9:43 am	#7
tony brady Hexode Join Date: Mar 2014 Location: Peacehaven, East Sussex, UK. Posts: 278	Re: BF194/195 by Siemens any good Restoration73 is correct, I have used Philips BF494 in TO92 before . The Siemens data sheet shows them as lockfit cases.

17th Sep 2016, 9:55 am	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: BF194/195 by Siemens any good The BF494/5s are difficult to find and pricey. Lots of other transistors will be fine as BF194/5 replacements in domestic radios. All my Lockfit experience has been with Mullards. If Siemens used the same production process then they're likely to suffer the same problems. They may even have been made by Mullard under contract.