Valve Identification & Restoration Advice of Circa 1931 Mains Radio - UK Vintage Radio Repair and Restoration Discussion Forum

DoctorWho · 8th Aug 2006, 6:34 pm

Recently other forum members have kindly tried to help me identify a mystery mains radio from circa 1931 which I recently bought. The thread about the identification can be found here as well as a picture of the set:

https://www.vintage-radio.net/forum/...ad.php?t=10335

I have since been able to sit down and have a look at the set, it's not been that easy as I'm not sure what make/model it is, but it's a pretty basic set with the following valve line-up (corrected from the other thread)

1 X Unidentified Metalised Valve with screw-top cap and 5-pin base.

1 X MM4V

1 X PM24M

1 X U10

Firstly can anyone suggest what this unidentified valve is most likely to be please?

Secondly, I have changed the 4 condensers which had not been previously been changed, the set powers up, the amplifier works brilliantly, when touching the gram sockets there is a very healthy hum. TYhe other condensers look to have been changed in recent years and seem fine.

When switching to medium or long wave though and using your finger as an aerial it picks up a couple of stations on medium wave, reasonably clearly but without a great deal of volume, using a loft aerial for some odd reason seems to result in a quieter signal than using my finger!

I am wondering if I should be looking at replacing the MM4V and/or the other unidentified 5-pin valve which, at the moment, is unidentified, or would anyone suggest another avenue here? The set has been fitted with a brand new PM24M and this works brilliantly as far as the amplifier is concerned.

Thanks in advance for any help.

All the best,

Peter.

Sideband · 8th Aug 2006, 10:25 pm

Quote:

Originally Posted by DoctorWho

1 X Unidentified Metalised Valve with screw-top cap and 5-pin base.

1 X MM4V

1 X PM24M

1 X U10

Firstly can anyone suggest what this unidentified valve is most likely to be please?

Hi Peter.

The unidentified valve could be an S4VB...I have a Philips set from 1933 with an almost identcal valve line-up.

With regard to your sensitivity problem...well it could be low emission valves but I think it might be worth checking aerial coupling capacitors and alignment

I changed the S4VB in my set which made a slight difference but realignment made an amazing difference.

Rich

DoctorWho · 9th Aug 2006, 10:18 am

Thanks for the suggestion Rich, that sounds like a good valve to try.

I agree about alignment, the only problem is aligning a set without any service data is difficult.

I have already changed the condensers, the only ones I have left alone were a couple of original mica ones, would you advise changing these too?

Would you imagine that an S4VB would work in this set? If so I'll order one of those and then go from there. I'll then try and work out how to go about the alignment of the set. It is difficult working on any set without any service data, but I'll give it a go, any tips would be very welcome.

Thanks again,

Peter.

Ed_Dinning · 9th Aug 2006, 12:25 pm

Hi Peter, if this is a band pass front end, look at the bottom coupling capacitor between the 2 sections, variations here or leakage can reduce sensitivity drastically.

Ed

DoctorWho · 9th Aug 2006, 5:03 pm

Thanks for the tip Ed, would this be a mica cap? I have changed all of the original wax/paper caps, so it's only the mica ones left.

Peter.

Ed_Dinning · 10th Aug 2006, 9:17 pm

Hi Peter, yes it will probably be mica and is usually under 100pF.

Ed

DoctorWho · 12th Aug 2006, 8:52 am

Thanks Ed, I'll have a look.

PJL · 12th Aug 2006, 9:55 pm

I have an early 30's TRF I restored which I came to the conclusion must have been a kit despite a good quality case and well built chassis. Maybe yours is too?

Trouble is you never know whether it ever worked properly. Mine uses a 354V as the detector which had the wrong anode load. I had to rewind one of the coils and it used twisted wire as a coupling which was absolutely hopeless.

There's no avoiding it, you'll need to get out the pen & paper and draw up the circuit diagram...Peter

Sideband · 12th Aug 2006, 11:41 pm

Quote:

Originally Posted by DoctorWho

Would you imagine that an S4VB would work in this set? If so I'll order one of those and then go from there.

Yes! Wouldn't have suggested it otherwise!!

There are other similar valves that would work I suppose (the MS4B for example) and as far as I am aware, they all have the same pin arrangement. The S4VB is getting difficult to obtain. The only one I had was a NOS and that is currently in use in my Philips 274A.

Rich.

DoctorWho · 13th Aug 2006, 6:12 pm

Makes sense

I'll give it a bash, thank you.

8th Aug 2006, 6:34 pm	#1
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Valve Identification & Restoration Advice of Circa 1931 Mains Radio Recently other forum members have kindly tried to help me identify a mystery mains radio from circa 1931 which I recently bought. The thread about the identification can be found here as well as a picture of the set: https://www.vintage-radio.net/forum/...ad.php?t=10335 I have since been able to sit down and have a look at the set, it's not been that easy as I'm not sure what make/model it is, but it's a pretty basic set with the following valve line-up (corrected from the other thread) 1 X Unidentified Metalised Valve with screw-top cap and 5-pin base. 1 X MM4V 1 X PM24M 1 X U10 Firstly can anyone suggest what this unidentified valve is most likely to be please? Secondly, I have changed the 4 condensers which had not been previously been changed, the set powers up, the amplifier works brilliantly, when touching the gram sockets there is a very healthy hum. TYhe other condensers look to have been changed in recent years and seem fine. When switching to medium or long wave though and using your finger as an aerial it picks up a couple of stations on medium wave, reasonably clearly but without a great deal of volume, using a loft aerial for some odd reason seems to result in a quieter signal than using my finger! I am wondering if I should be looking at replacing the MM4V and/or the other unidentified 5-pin valve which, at the moment, is unidentified, or would anyone suggest another avenue here? The set has been fitted with a brand new PM24M and this works brilliantly as far as the amplifier is concerned. Thanks in advance for any help. All the best, Peter. Last edited by Darren-UK; 15th Jul 2011 at 2:06 pm.

9th Aug 2006, 10:18 am	#3
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Thanks for the suggestion Rich, that sounds like a good valve to try. I agree about alignment, the only problem is aligning a set without any service data is difficult. I have already changed the condensers, the only ones I have left alone were a couple of original mica ones, would you advise changing these too? Would you imagine that an S4VB would work in this set? If so I'll order one of those and then go from there. I'll then try and work out how to go about the alignment of the set. It is difficult working on any set without any service data, but I'll give it a go, any tips would be very welcome. Thanks again, Peter.

9th Aug 2006, 12:25 pm	#4
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Hi Peter, if this is a band pass front end, look at the bottom coupling capacitor between the 2 sections, variations here or leakage can reduce sensitivity drastically. Ed

9th Aug 2006, 5:03 pm	#5
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Thanks for the tip Ed, would this be a mica cap? I have changed all of the original wax/paper caps, so it's only the mica ones left. Peter.

10th Aug 2006, 9:17 pm	#6
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Hi Peter, yes it will probably be mica and is usually under 100pF. Ed

12th Aug 2006, 8:52 am	#7
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Thanks Ed, I'll have a look.

12th Aug 2006, 9:55 pm	#8
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio I have an early 30's TRF I restored which I came to the conclusion must have been a kit despite a good quality case and well built chassis. Maybe yours is too? Trouble is you never know whether it ever worked properly. Mine uses a 354V as the detector which had the wrong anode load. I had to rewind one of the coils and it used twisted wire as a coupling which was absolutely hopeless. There's no avoiding it, you'll need to get out the pen & paper and draw up the circuit diagram...Peter

13th Aug 2006, 6:12 pm	#10
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Valve Identification & Restoration Advice of Circa 1931 Mains Radio Makes sense I'll give it a bash, thank you.