Unknown Pye Radio - Skip Salvage - UK Vintage Radio Repair and Restoration Discussion Forum

VNV4All · 4th Jul 2018, 9:46 pm

Hi, my first proper post...

I've recently acquired a vintage Pye radio receiver from a skip.
It's missing its output transformer, but all else seems to be present, and OK cosmetic condition albeit some wires disconnected.

It's a four valve mains unit with an APV4 rectifier, AC2 Pentode, TH4B and VP4B RF valves.

This is my second delve into valve amplifiers and my first into valve radio, so I'm hoping to learn a bit more this time having a lot more life experience to fall back on since last time (Leak TL10 restoration in the late 90's), and I'd like to start to learn what I'm actually doing regarding the valves, rather than just getting the job done.

I've attached some photos of the unit, it appears to be similar to the MP, but I've not managed to locate an MP variant with an AC2 Pentode, so anyone's help would be appreciated here.

I suppose first off I need to locate a schematic and test the valves I have to see if they are functional. I'll try to grab the data sheets, and check the heaters if nothing else this weekend.

So any help or advice would be appreciated.

Thanks
Jon

Station X · 4th Jul 2018, 10:14 pm

It can be useful to test the valves for heater continuity. Apart from that, the best place to test valves is in the set. Voltage readings will tell you all you need to know.

Peter.N. · 5th Jul 2018, 10:07 am

It's in brilliant condition - or have you been cleaning it?

Peter

VNV4All · 5th Jul 2018, 11:15 am

Thanks Peter, I've done nothing to this unit yet, bar removing the chassis from the housing. As I say some wires have become disconnected around the transformer, and the OP transformer is missing, but yes looks in good condition.

Further investigation last night brought me to the Pye RS4, which looks an identical chassis, but not using an AC2 or APV4 (The RS4 uses a Pen4DD and a DW4/350), do I have incorrect valves in the unit?

Quote:

Originally Posted by Station X

It can be useful to test the valves for heater continuity. Apart from that, the best place to test valves is in the set. Voltage readings will tell you all you need to know.

Thanks, OK, yes I'll test the continuity. Is it OK to power the heaters with no other voltages present?

Close up of full valve line-up attached.
Rgds
Jon

Sideband · 5th Jul 2018, 1:57 pm

It's amazing what some people throw out! That's a good find. The sets aren't particularly rare but to find one in that condition for nothing has got to be a bonus!

Ed_Dinning · 5th Jul 2018, 4:30 pm

Hi Jon, I may be able to find you an op trans.
I take it that it is a 3R speaker, let us know what the op valve is when you get it sorted.

Ed

VNV4All · 5th Jul 2018, 5:13 pm

Hi Ed, Thanks, yes cone has a DC resistance of 3R.

HamishBoxer · 5th Jul 2018, 5:18 pm

Do not forget to change the output grid coupling cap and possibly run up through a lamp limiter.

VNV4All · 5th Jul 2018, 5:27 pm

Thanks, yes I have a varaic and a halogen limiter, but need to confirm a valid schematic, replace the loose wiring and confirm the connections of the possibly incorrect OP valve, then I'll need to look at replacing caps yes.

Do I need an OP transformer fitted to power it up?

The AC2/PEN/DD fitted looks on first glance to have a different pinout, but the same socket to the PEN4DD on the RS4, so... assuming it is an RS4 I need to double check the pinout to see if someone has modified it to work with the AC2/PEN/DD or incorrectly fitted it while trying to get it to work.

I've downloaded the schematic for the RS4 and all of the valve data for the RS4 valves, plus the ones fitted to my chassis. I'll double check and cross reference tomorrow.

akuram1 · 5th Jul 2018, 6:18 pm

Seems unusual to find a Mazda valve fitted in a Pye. Think you need to check this out.

McMurdo · 5th Jul 2018, 7:39 pm

You will need an output transformer in the circuit if you don't want to run the risk of damaging the output valve.

VNV4All · 5th Jul 2018, 7:53 pm

Quote:

Originally Posted by Ed_Dinning

Hi Jon, I may be able to find you an op trans.
I take it that it is a 3R speaker, let us know what the op valve is when you get it sorted.

Is this is a field coil speaker, not come across those till this evening, although there appears not to be a field coil if this is??, the RS4 references a 'field coil' choke on the schematic. The chassis does not have a HT choke, so must have either been integrated into the output transformer or something.

As mentioned the voice coil measured up at 3R DC

Advice appreciated...
Thanks

TonyDuell · 5th Jul 2018, 7:57 pm

That looks like a permanent magenet speaker to me (works in the same way as a modern speaker).

I wonder if the speaker was replaced at some point which might explain why the output transformer is missing.

VNV4All · 5th Jul 2018, 8:04 pm

Thats definitely an option, from the marks on the enclosure, there has been a transformer (Choke/Transformer) frame screwed to the base next to the speaker at some point, but obviously cannot tell if this is an original placement or otherwise.

Station X · 5th Jul 2018, 8:25 pm

Quote:

Originally Posted by VNV4All

Quote:

Originally Posted by Station X

It can be useful to test the valves for heater continuity. Apart from that, the best place to test valves is in the set. Voltage readings will tell you all you need to know.

Thanks, OK, yes I'll test the continuity. Is it OK to power the heaters with no other voltages present?

Jon

I'd say it was OK for a short period, but others might think there's a risk of cathode poisoning. You could just check continuity between valve pins with a meter on ohms range. It is good idea to clean any tarnishing off the valve pins too.

ms660 · 5th Jul 2018, 8:27 pm

Where's the reservoir capacitor etc?

Lawrence.

high_vacuum_house · 5th Jul 2018, 8:34 pm

That's what I was thinking. The underside of the chassis looks rather Spartan than normal.

Should not be too difficult to fit a BVWS dual smoothing and reservoir electrolytic capacitor underneath

Christopher Capener

ms660 · 5th Jul 2018, 8:44 pm

There's a grounding lug North-West of the volume control that looks as though its had a snip.

Lawrence.

VNV4All · 5th Jul 2018, 8:54 pm

Quote:

Originally Posted by ms660

Where's the reservoir capacitor etc?

Good call, missing is my best guess.
C29 should be an 8+8uF capacitor, this is nowhere to be seen, I assume it should be around the red and black coming to and from the non existent field coil.

Any idea what value the choke (assuming I replace it with a choke, and not a field coil) should be?

ms660 · 5th Jul 2018, 9:23 pm

I think somewhere around 10H was a common value for HT choke for receivers, trouble is the DC resistance will probably be a lot lot lower (only 300-500 ohms maybe) than the DC resistance of a loudspeaker field coil, if going by the RS4 schematic that's 3,000 ohms, one suggestion would be to get a standard 10 henry choke that's good for at least 60mA, fit a 16uf for the reservoir and filter and fit a surge limiter in each anode of rectifier or between the cathode of the rectifier and the reservoir capacitor to drop the HT to what it should be, not sure what values off hand because it's a bit too hot for me to think straight at the moment

Lawrence.

4th Jul 2018, 9:46 pm	#1
VNV4All Triode Join Date: Jul 2018 Location: Worcester, Worcestershire, UK. Posts: 13	Unknown Pye Radio - Skip Salvage Hi, my first proper post... I've recently acquired a vintage Pye radio receiver from a skip. It's missing its output transformer, but all else seems to be present, and OK cosmetic condition albeit some wires disconnected. It's a four valve mains unit with an APV4 rectifier, AC2 Pentode, TH4B and VP4B RF valves. This is my second delve into valve amplifiers and my first into valve radio, so I'm hoping to learn a bit more this time having a lot more life experience to fall back on since last time (Leak TL10 restoration in the late 90's), and I'd like to start to learn what I'm actually doing regarding the valves, rather than just getting the job done. I've attached some photos of the unit, it appears to be similar to the MP, but I've not managed to locate an MP variant with an AC2 Pentode, so anyone's help would be appreciated here. I suppose first off I need to locate a schematic and test the valves I have to see if they are functional. I'll try to grab the data sheets, and check the heaters if nothing else this weekend. So any help or advice would be appreciated. Thanks Jon Attached Thumbnails

4th Jul 2018, 10:14 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Unknown Pye Radio - Skip Salvage It can be useful to test the valves for heater continuity. Apart from that, the best place to test valves is in the set. Voltage readings will tell you all you need to know. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

5th Jul 2018, 10:07 am	#3
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Unknown Pye Radio - Skip Salvage It's in brilliant condition - or have you been cleaning it? Peter

5th Jul 2018, 1:57 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,578	Re: Unknown Pye Radio - Skip Salvage It's amazing what some people throw out! That's a good find. The sets aren't particularly rare but to find one in that condition for nothing has got to be a bonus! __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

5th Jul 2018, 4:30 pm	#6
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Unknown Pye Radio - Skip Salvage Hi Jon, I may be able to find you an op trans. I take it that it is a 3R speaker, let us know what the op valve is when you get it sorted. Ed

5th Jul 2018, 5:13 pm	#7
VNV4All Triode Join Date: Jul 2018 Location: Worcester, Worcestershire, UK. Posts: 13	Re: Unknown Pye Radio - Skip Salvage Hi Ed, Thanks, yes cone has a DC resistance of 3R.

5th Jul 2018, 5:18 pm	#8
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: Unknown Pye Radio - Skip Salvage Do not forget to change the output grid coupling cap and possibly run up through a lamp limiter. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

5th Jul 2018, 5:27 pm	#9
VNV4All Triode Join Date: Jul 2018 Location: Worcester, Worcestershire, UK. Posts: 13	Re: Unknown Pye Radio - Skip Salvage Thanks, yes I have a varaic and a halogen limiter, but need to confirm a valid schematic, replace the loose wiring and confirm the connections of the possibly incorrect OP valve, then I'll need to look at replacing caps yes. Do I need an OP transformer fitted to power it up? The AC2/PEN/DD fitted looks on first glance to have a different pinout, but the same socket to the PEN4DD on the RS4, so... assuming it is an RS4 I need to double check the pinout to see if someone has modified it to work with the AC2/PEN/DD or incorrectly fitted it while trying to get it to work. I've downloaded the schematic for the RS4 and all of the valve data for the RS4 valves, plus the ones fitted to my chassis. I'll double check and cross reference tomorrow.

5th Jul 2018, 6:18 pm	#10
akuram1 Pentode Join Date: Sep 2009 Location: Dundee, UK. Posts: 158	Re: Unknown Pye Radio - Skip Salvage Seems unusual to find a Mazda valve fitted in a Pye. Think you need to check this out.

5th Jul 2018, 7:39 pm	#11
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,273	Re: Unknown Pye Radio - Skip Salvage You will need an output transformer in the circuit if you don't want to run the risk of damaging the output valve. __________________ Kevin

5th Jul 2018, 7:57 pm	#13
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,215	Re: Unknown Pye Radio - Skip Salvage That looks like a permanent magenet speaker to me (works in the same way as a modern speaker). I wonder if the speaker was replaced at some point which might explain why the output transformer is missing.

5th Jul 2018, 8:04 pm	#14
VNV4All Triode Join Date: Jul 2018 Location: Worcester, Worcestershire, UK. Posts: 13	Re: Unknown Pye Radio - Skip Salvage Thats definitely an option, from the marks on the enclosure, there has been a transformer (Choke/Transformer) frame screwed to the base next to the speaker at some point, but obviously cannot tell if this is an original placement or otherwise.

5th Jul 2018, 8:27 pm	#16
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Unknown Pye Radio - Skip Salvage Where's the reservoir capacitor etc? Lawrence.

5th Jul 2018, 8:34 pm	#17
high_vacuum_house Octode Join Date: May 2003 Location: Belper Derbyshire Posts: 1,936	Re: Unknown Pye Radio - Skip Salvage That's what I was thinking. The underside of the chassis looks rather Spartan than normal. Should not be too difficult to fit a BVWS dual smoothing and reservoir electrolytic capacitor underneath Christopher Capener __________________ Interests in the collection and restoration of Tefifon players and 405 line television

5th Jul 2018, 8:44 pm	#18
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Unknown Pye Radio - Skip Salvage There's a grounding lug North-West of the volume control that looks as though its had a snip. Lawrence.

5th Jul 2018, 9:23 pm	#20
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Unknown Pye Radio - Skip Salvage I think somewhere around 10H was a common value for HT choke for receivers, trouble is the DC resistance will probably be a lot lot lower (only 300-500 ohms maybe) than the DC resistance of a loudspeaker field coil, if going by the RS4 schematic that's 3,000 ohms, one suggestion would be to get a standard 10 henry choke that's good for at least 60mA, fit a 16uf for the reservoir and filter and fit a surge limiter in each anode of rectifier or between the cathode of the rectifier and the reservoir capacitor to drop the HT to what it should be, not sure what values off hand because it's a bit too hot for me to think straight at the moment Lawrence.