Help with Pye new baby Q valve identity - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Mr Moose · 27th Aug 2018, 8:55 pm

Hello,
The damaged valve is a Marconi double valve with a top cap and presumably a 2V valve.
The only valve I know that fits this description is the triode-hexode X23.
The unmetalized version is shown here https://www.radiomuseum.org/tubes/tube_x23.html.
This valve is a frequency changer and given that the other valves are Mullard is almost certainly a replacement. The original valve would very probably have been a Mullard FC2A.
Yours, Richard

Nukeybrown · 27th Aug 2018, 9:00 pm

I think your right richard x23. Now would anyone have one , probably not

julie_m · 27th Aug 2018, 9:13 pm

Battery sets usually employed an octode frequency changer (someone mentioned FC2a earlier, which would fit with this); triode-hexode frequency changers were most often found in mains sets.

I certainly would not expect to see two different frequency changer valves in the same set. (Barring that weird [Tesla?] circuit, which used the hexode of a UCH21 as an IF amplifier and the triode as audio preamp.)

Station X · 27th Aug 2018, 9:17 pm

Can we be certain that the correct valves were fitted though? I'd prefer to believe the service sheet on RM.

FC2A, VP2B, TDD2A and QP22B.

Would the circuit have needed to be modified to take an X23?

Nukeybrown · 27th Aug 2018, 10:53 pm

So whats my option's for a valve to replace the damaged one? Please

Station X · 28th Aug 2018, 8:59 am

FC2A and X23 have different pin outs.

You'll need to compare the wiring with the circuit diagram to check whether it's been changed to suit an X23.

ms660 · 28th Aug 2018, 10:26 am

Same electrode function pinouts so far as I can make out:

X23 mixer anode...Pin 7. FC2A mixer anode...Pin 7.

X23 mixer screen (g2,g4)…Pin 3. FC2A mixer screen (g3,g5)...Pin 3.

X23 mixer signal grid (g1)...T/cap. FC2A mixer signal grid (g4)...T/cap.

X23 osc grid (triode)...Pin 2. FC2A osc grid (g1)...Pin 2.

X23 osc anode (triode)...Pin 1. FC2A osc anode (g2)...Pin 1.

Filaments for both types...Pins 4&5.

Metalizing for both types...Pin 6. FC2A suppressor grid (g6)...Pin 6.

Lawrence.

Station X · 28th Aug 2018, 10:43 am

I haven't done any detailed checks, but "Radio Valve Data" shows the X23 as having pinout B7 34 and FC2A as having pinout B7 1.

The pinout diagrams show pin 2 as being the metalizing and cathode respectively.

ms660 · 28th Aug 2018, 10:48 am

Quote:

Originally Posted by Station X

I haven't done any detailed checks, but "Radio Valve Data" shows the X23 as having pinout B7 34 and FC2A as having pinout B7 1.

The pinout diagrams show pin 2 as being the metalizing and cathode respectively.

I have the same book, pin 1's at North.

Lawrence.

Station X · 28th Aug 2018, 10:57 am

Quite right.

The differences appear to be just a case of nomenclature.

I was looking at base B7 35 in error

The upshot is that the OP can use an X23 or FC2A depending on what he can get hold of.

Ed_Dinning · 28th Aug 2018, 8:02 pm

Hi Nukey, if you have no luck give me a PM next week as I may have some of these.

Ed

Nukeybrown · 28th Aug 2018, 8:07 pm

Thanks ed thought you might have some hiding in the store garage lol

27th Aug 2018, 8:55 pm	#21
Mr Moose Octode Join Date: Jul 2008 Location: Gloucestershire, UK. Posts: 1,043	Re: Help with Pye new baby Q valve indentity Hello, The damaged valve is a Marconi double valve with a top cap and presumably a 2V valve. The only valve I know that fits this description is the triode-hexode X23. The unmetalized version is shown here https://www.radiomuseum.org/tubes/tube_x23.html. This valve is a frequency changer and given that the other valves are Mullard is almost certainly a replacement. The original valve would very probably have been a Mullard FC2A. Yours, Richard Last edited by Mr Moose; 27th Aug 2018 at 9:16 pm.

27th Aug 2018, 9:00 pm	#22
Nukeybrown Heptode Join Date: Jan 2016 Location: Gateshead, Tyne and Wear, UK. Posts: 504	Re: Help with Pye new baby Q valve indentity I think your right richard x23. Now would anyone have one , probably not

27th Aug 2018, 9:13 pm	#23
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Help with Pye new baby Q valve indentity Battery sets usually employed an octode frequency changer (someone mentioned FC2a earlier, which would fit with this); triode-hexode frequency changers were most often found in mains sets. I certainly would not expect to see two different frequency changer valves in the same set. (Barring that weird [Tesla?] circuit, which used the hexode of a UCH21 as an IF amplifier and the triode as audio preamp.) __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

27th Aug 2018, 9:17 pm	#24
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Pye new baby Q valve indentity Can we be certain that the correct valves were fitted though? I'd prefer to believe the service sheet on RM. FC2A, VP2B, TDD2A and QP22B. Would the circuit have needed to be modified to take an X23? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

27th Aug 2018, 10:53 pm	#25
Nukeybrown Heptode Join Date: Jan 2016 Location: Gateshead, Tyne and Wear, UK. Posts: 504	Re: Help with Pye new baby Q valve indentity So whats my option's for a valve to replace the damaged one? Please

28th Aug 2018, 8:59 am	#26
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Pye new baby Q valve indentity FC2A and X23 have different pin outs. You'll need to compare the wiring with the circuit diagram to check whether it's been changed to suit an X23. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

28th Aug 2018, 10:26 am	#27
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Help with Pye new baby Q valve identity Same electrode function pinouts so far as I can make out: X23 mixer anode...Pin 7. FC2A mixer anode...Pin 7. X23 mixer screen (g2,g4)…Pin 3. FC2A mixer screen (g3,g5)...Pin 3. X23 mixer signal grid (g1)...T/cap. FC2A mixer signal grid (g4)...T/cap. X23 osc grid (triode)...Pin 2. FC2A osc grid (g1)...Pin 2. X23 osc anode (triode)...Pin 1. FC2A osc anode (g2)...Pin 1. Filaments for both types...Pins 4&5. Metalizing for both types...Pin 6. FC2A suppressor grid (g6)...Pin 6. Lawrence. Last edited by ms660; 28th Aug 2018 at 10:29 am. Reason: Clarification

28th Aug 2018, 10:43 am	#28
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Pye new baby Q valve identity I haven't done any detailed checks, but "Radio Valve Data" shows the X23 as having pinout B7 34 and FC2A as having pinout B7 1. The pinout diagrams show pin 2 as being the metalizing and cathode respectively. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

28th Aug 2018, 10:57 am	#30
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Pye new baby Q valve identity Quite right. The differences appear to be just a case of nomenclature. I was looking at base B7 35 in error The upshot is that the OP can use an X23 or FC2A depending on what he can get hold of. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

28th Aug 2018, 8:02 pm	#31
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Help with Pye new baby Q valve identity Hi Nukey, if you have no luck give me a PM next week as I may have some of these. Ed

28th Aug 2018, 8:07 pm	#32
Nukeybrown Heptode Join Date: Jan 2016 Location: Gateshead, Tyne and Wear, UK. Posts: 504	Re: Help with Pye new baby Q valve identity Thanks ed thought you might have some hiding in the store garage lol