Replacing valves with FET's. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

GJR 11L · 22nd Jun 2007, 9:57 pm

Just found this thread while searching for a 1L6 equivalent!

Does anyone have a circuit for such a device please? Or a number for a valve that will sub the rare, expensive one in question?

Well a bloke has to try!

dave walsh · 22nd Jun 2007, 10:39 pm

There are circuits around as mentioned already-I've seen some of them e and there is an HRO conversion where some valves were replaced by FET's. I'll see if I can root anything out but don't hold your breath. Dave

joe · 22nd Jun 2007, 10:40 pm

John,

I believe that the nearest equivalent for a 1L6 is a DK92. It is (from memory) a pin for pin replacement, but re-alignment will be necessary and even then the HF performance will fall far short of the original.

I do have a circuit, indeed an article on an FET replacement which I'll try and fish out tomorrow and post. I also have an article that was written by Jim Duckworth on the subject which I'll also try & find tomorrow.

Joe

OldBoffin · 22nd Jun 2007, 11:03 pm

Hi All,
I've replaced all the valves in a car radio with FETs,Transistors and an audio amp very sucessfully - it reduces the 12volt load substantially from that taken by the Vib pack! (but I've left the valve holders if anyone wants to restore to original - Its an ECKO CR152 which I want to sell for my Cancer charities. Also used FETs in a SPY Radio instead of the loctal frequency changer OK. so have a go!
OldBoffin.

XTC · 22nd Jun 2007, 11:14 pm

Googling found this page on making a 1L6 solid state subsitute.

http://antiqueradios.com/marc/1l6.html

complete with circuit diagram.

There are also 1L6 valves and solid state substitutes available on the US version of a certain internet auction site.

Pete.

GJR 11L · 23rd Jun 2007, 12:01 am

Thanks Pete, very useful, I would rather keep my T.O. original if I can as I've heard a good one with all the correct valves and it was lovely, but that info looks most interesting.

adrian · 23rd Jun 2007, 5:10 am

Quote:

Originally Posted by GJR 11L

Just found this thread while searching for a 1L6 equivalent!

Does anyone have a circuit for such a device please? Or a number for a valve that will sub the rare, expensive one in question?

Well a bloke has to try!

There's a chap on Ebay selling a newer version of the solid-state 1L6 at around US$35. See my page http://www.zenithtrans-oceanic.porta....co.uk/1l6.htm for details.

Adrian

adrian · 23rd Jun 2007, 5:11 am

Quote:

Originally Posted by joe

John,

I believe that the nearest equivalent for a 1L6 is a DK92. It is (from memory) a pin for pin replacement, but re-alignment will be necessary and even then the HF performance will fall far short of the original.

I do have a circuit, indeed an article on an FET replacement which I'll try and fish out tomorrow and post. I also have an article that was written by Jim Duckworth on the subject which I'll also try & find tomorrow.

Joe

See my page at http://www.zenithtrans-oceanic.porta....co.uk/1l6.htm for more details (including the Duckworth Experiments) on 1L6/DK92 interchangeability.

Adrian

GJR 11L · 23rd Jun 2007, 9:04 am

Good site there. Adrian, although the pictures page is telling me that it doesn't want to cooperate. (404)

I found that solid state alternative on eBay U.S. last night and it looks like a good plan. Tried the set with a DK92 earlier and that seemed ok, if, as expected, a little weak at Higher frequencies, but I have several good DK92s and at least one of those gets my set working well enough to listen to the broadcast band and better that use than have it sitting idle while I seek out parts!

Thanks for your link.

Mike Phelan · 24th Jun 2007, 8:17 am

Referring to one of the (very) early posts on the PL802 replacements, the one we used in the 70s when supplies of the valve dried up was from Wizard Electronics in Manchester. It used a BF458 and, I think, a BC107 as an emitter follower to 'look like' a valve grid input.
Naturally, we only bought one of them - the rest you can guess ...

Sorry, cannot find the circuit, but it was fairly simple.

Steve_P · 24th Jun 2007, 5:06 pm

I've got some of these somewhere in this mess! Wasn't there a problem with them not physically fitting some sets?

Cheers,

Steve P

joe · 25th Jun 2007, 4:25 pm

Hi GJR11L

Pete(XTC) has beaten me to it by several days but I've attached the article by Jim Duckworth which originally appeared in the BVWS Bulletin.

If its too small or not clear enough to read then PM me & I'll arrange a copy by snail-mail.

Joe

igranic · 25th Jun 2007, 6:08 pm

Joe,

In which issue of The Bulletin was this published? Armed with this information, interested BVWS members should be able to find it on their BVWS CD of backnumbers - if they can find the CD!

Edward

murphyv310 · 25th Jun 2007, 6:49 pm

Hi.
I had one of these Zenith sets with the usual 1L6 fault, the DK92 works ok on lower frequencies but if you look at the set the valve holder is larger than the rest as the set was designed for an octal valve. I eventually fitted a DK32 and octal base this restored full shortwave performance.
Trevor

MALC SCOTT · 25th Jun 2007, 7:42 pm

Quote:

Originally Posted by Steve_P

I've got some of these somewhere in this mess! Wasn't there a problem with them not physically fitting some sets?

Hi, Yes you are correct. If these solid state devices were fitted to the early Pye/Ekco sets, the heatsink could short out to the metal frame of the i/f deck!

They did improve picture quality on sets with a low crt. Cheers, Malc.

joe · 25th Jun 2007, 10:48 pm

Edward (Igranic)

Unfortunately I don't know! The article I scanned was a photocopy sent to me by the author following a conversation at a swapmeet. If I come across the answer via any other route then I'll post it.

I doubt if its old enough to be on the CD Rom of backnumbers of The Bulletin.

Joe

Dave Moll · 26th Jun 2007, 11:45 am

Quote:

Originally Posted by igranic

Joe,

In which issue of The Bulletin was this published?

Edward

Volume 22 number 4 Winter 1997 (pp 26-27).

igranic · 26th Jun 2007, 1:44 pm

Dave,
Thanks for supplying the issue number.

Joe
You were abolutely correct in doubting if it would be on the CD, which only goes as far as Volume 20.

Does any forum member have a copy of The Bulletin, Volume 22 number 4 Winter 1997 (pp 26-27) they can scan and post here? It would save joe the copying and postage.

Dave Moll · 26th Jun 2007, 5:44 pm

Hopefully, at the expense of the pictures on the first page, this is a more readable copy of the text (scanned as "line art"). I had to reduce the resolution, however, to upload it to the forum

Incidentally, I hope it is acceptable to the BVWS committee for this to be reproduced here.

GJR 11L · 28th Jun 2007, 5:44 pm

Quote:

Originally Posted by joe

Hi GJR11L

Pete(XTC) has beaten me to it by several days but I've attached the article by Jim Duckworth which originally appeared in the BVWS Bulletin.

If its too small or not clear enough to read then PM me & I'll arrange a copy by snail-mail.

Joe

That works fine for me, thanks Joe and others, though as I may have mentioned in another thread the 1L6 is actually fine after all, typically, this was only discovered after (ab)using a DK92 which must have taken some muck out of the socket so that, when replaced, the 1L6 was, and remains, able to do its job properly.

I've had it [1L6] tested today (thanks Greg, please sell your tester to me!) and the result was very encouraging, so have cleaned all valveholders properly now.

However, I intend to explore the solid state alternative simply as an experiment, the T600 is far too good to have sitting in storage but I don't really want to wear out the 1L6 I have or the new old stock one I just bought from the good old U.S of A for very sensible money.

22nd Jun 2007, 9:57 pm	#21
GJR 11L Heptode Join Date: May 2004 Location: Ellington, Northumberland, UK. Posts: 815	Re: Valves Out, FETs In Just found this thread while searching for a 1L6 equivalent! Does anyone have a circuit for such a device please? Or a number for a valve that will sub the rare, expensive one in question? Well a bloke has to try! __________________ John.

22nd Jun 2007, 10:39 pm	#22
dave walsh Dekatron Join Date: Jan 2006 Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex. Posts: 5,817	Re: Valves Out, FETs In There are circuits around as mentioned already-I've seen some of them e and there is an HRO conversion where some valves were replaced by FET's. I'll see if I can root anything out but don't hold your breath. Dave

22nd Jun 2007, 10:40 pm	#23
joe Rest in Peace Join Date: Apr 2003 Location: Edgware, North London. Posts: 307	Re: Valves Out, FETs In John, I believe that the nearest equivalent for a 1L6 is a DK92. It is (from memory) a pin for pin replacement, but re-alignment will be necessary and even then the HF performance will fall far short of the original. I do have a circuit, indeed an article on an FET replacement which I'll try and fish out tomorrow and post. I also have an article that was written by Jim Duckworth on the subject which I'll also try & find tomorrow. Joe

22nd Jun 2007, 11:03 pm	#24
OldBoffin Retired Dormant Member Join Date: Jan 2007 Location: Rugeley, Staffordshire, UK. Posts: 54	Re: Valves Out, FETs In Hi All, I've replaced all the valves in a car radio with FETs,Transistors and an audio amp very sucessfully - it reduces the 12volt load substantially from that taken by the Vib pack! (but I've left the valve holders if anyone wants to restore to original - Its an ECKO CR152 which I want to sell for my Cancer charities. Also used FETs in a SPY Radio instead of the loctal frequency changer OK. so have a go! OldBoffin.

22nd Jun 2007, 11:14 pm	#25
XTC Retired Dormant Member Join Date: Oct 2004 Location: Bristol, UK. Posts: 837	Re: Valves Out, FETs In Googling found this page on making a 1L6 solid state subsitute. http://antiqueradios.com/marc/1l6.html complete with circuit diagram. There are also 1L6 valves and solid state substitutes available on the US version of a certain internet auction site. Pete.

23rd Jun 2007, 12:01 am	#26
GJR 11L Heptode Join Date: May 2004 Location: Ellington, Northumberland, UK. Posts: 815	Re: Valves Out, FETs In Thanks Pete, very useful, I would rather keep my T.O. original if I can as I've heard a good one with all the correct valves and it was lovely, but that info looks most interesting. __________________ John.

23rd Jun 2007, 9:04 am	#29
GJR 11L Heptode Join Date: May 2004 Location: Ellington, Northumberland, UK. Posts: 815	Re: Valves Out, FETs In Good site there. Adrian, although the pictures page is telling me that it doesn't want to cooperate. (404) I found that solid state alternative on eBay U.S. last night and it looks like a good plan. Tried the set with a DK92 earlier and that seemed ok, if, as expected, a little weak at Higher frequencies, but I have several good DK92s and at least one of those gets my set working well enough to listen to the broadcast band and better that use than have it sitting idle while I seek out parts! Thanks for your link. __________________ John.

24th Jun 2007, 8:17 am	#30
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Valves Out, FETs In Referring to one of the (very) early posts on the PL802 replacements, the one we used in the 70s when supplies of the valve dried up was from Wizard Electronics in Manchester. It used a BF458 and, I think, a BC107 as an emitter follower to 'look like' a valve grid input. Naturally, we only bought one of them - the rest you can guess ... Sorry, cannot find the circuit, but it was fairly simple. __________________ Mike.

24th Jun 2007, 5:06 pm	#31
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Valves Out, FETs In I've got some of these somewhere in this mess! Wasn't there a problem with them not physically fitting some sets? Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

25th Jun 2007, 4:25 pm	#32
joe Rest in Peace Join Date: Apr 2003 Location: Edgware, North London. Posts: 307	Re: Valves Out, FETs In Hi GJR11L Pete(XTC) has beaten me to it by several days but I've attached the article by Jim Duckworth which originally appeared in the BVWS Bulletin. If its too small or not clear enough to read then PM me & I'll arrange a copy by snail-mail. Joe Attached Thumbnails

25th Jun 2007, 6:08 pm	#33
igranic Rest in Peace Join Date: Jan 2005 Location: North Bedfordshire, UK. Posts: 395	Re: Valves Out, FETs In Joe, In which issue of The Bulletin was this published? Armed with this information, interested BVWS members should be able to find it on their BVWS CD of backnumbers - if they can find the CD! Edward

25th Jun 2007, 6:49 pm	#34
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Valves Out, FETs In Hi. I had one of these Zenith sets with the usual 1L6 fault, the DK92 works ok on lower frequencies but if you look at the set the valve holder is larger than the rest as the set was designed for an octal valve. I eventually fitted a DK32 and octal base this restored full shortwave performance. Trevor __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

25th Jun 2007, 10:48 pm	#36
joe Rest in Peace Join Date: Apr 2003 Location: Edgware, North London. Posts: 307	Re: Valves Out, FETs In Edward (Igranic) Unfortunately I don't know! The article I scanned was a photocopy sent to me by the author following a conversation at a swapmeet. If I come across the answer via any other route then I'll post it. I doubt if its old enough to be on the CD Rom of backnumbers of The Bulletin. Joe

26th Jun 2007, 1:44 pm	#38
igranic Rest in Peace Join Date: Jan 2005 Location: North Bedfordshire, UK. Posts: 395	Re: Valves Out, FETs In Dave, Thanks for supplying the issue number. Joe You were abolutely correct in doubting if it would be on the CD, which only goes as far as Volume 20. Does any forum member have a copy of The Bulletin, Volume 22 number 4 Winter 1997 (pp 26-27) they can scan and post here? It would save joe the copying and postage.

26th Jun 2007, 5:44 pm	#39
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	Re: Valves Out, FETs In Hopefully, at the expense of the pictures on the first page, this is a more readable copy of the text (scanned as "line art"). I had to reduce the resolution, however, to upload it to the forum Incidentally, I hope it is acceptable to the BVWS committee for this to be reproduced here. Attached Thumbnails __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)