Double 2 radio - UK Vintage Radio Repair and Restoration Discussion Forum

EF80TVVALVE · 19th Jun 2020, 10:26 pm

Hi All,

Does anyone have a schematic or even an example of one of these small two valve 'double two' radio receivers. I'm attempting to find some information in order to get mine back in one piece but I'm not too familiar with these early sets to work from nothing and there seems to be very little information on them. Failing that if anyone would like to solve the puzzle and have a go then let me know and I can send it to a member who would be able to get it going again.

crackle · 20th Jun 2020, 7:52 am

I assume you dont mean this Regentone Double two https://www.radiomuseum.org/r/regentone_double_two.html

Mike

Cobaltblue · 20th Jun 2020, 8:53 am

The Double 2 Logo was used by Hustler Simpson and Web around 1930.

There was an an article in one of the Radio Magazines but I cannot remember which one.

A Double 2 was the cover story on the BVWS magazine VOL 16 No 2

https://www.bvws.org.uk/publications...letin_16_2.pdf

Do you have the same set? or another model.

The usual brand name for H S W was Aerodyne ISTR.

Cheers

Mike T

EF80TVVALVE · 20th Jun 2020, 10:05 am

Hi,

Mike is right, the set is the one made by Hustler Simpson and Webb. I have seen the cover story on the BVWS and it is the same model, but with some differences. One difference is the resistor from the tuning variable capacitor to grid also has a capacitor in parallel on mine. The MW coil also seems to have two seperate windings from what I can measure, although I need to remove this and check properly as a lot of the connections are very dirty. Another difference is that mine doesn't have the resistor fitted from grid to cathode on the first valve.

It is fairly easy to work out the 4 pin connections of the valves from looking inside the envelope so that is no problem. The bigger problem is the coil connections and differences I have from the small piece of schematic on the BVWS cover. I've looked at other 0-V-1 circuits and whilst none are exactly the same the will help somewhat with getting some of it together.

I've never found a schematic for the double 2 so I don't even know if one exists, finding another set would be helpful but again I've never came across one, although I know that there must be at least two more out there somewhere!

Cobaltblue · 20th Jun 2020, 10:18 am

You often see that arrangement where the grid leak resistor is in Parallel with the Capacitor rather than the grid leak connecting to filament or cathode. Thats a classic grid leak detector. It could be the design in the article is anode bend detection and the detector is getting a small bias from the filament supply.

It's not clear if the set is one of Normans own it looks as if he drew out the circuit or at least part of it for the cover.

Did you look at the letters pages of the Bulletin over the next year or so? there were two letters in Vol 16 no3 and one especially mentions the "lack" of a grid leak resistor so it seems more than one arrangement.

Cheers

Mike T

EF80TVVALVE · 20th Jun 2020, 10:40 am

Hi Mike,

Yes I did read the letters from the next issue although it may be worth me looking through more and seeing if it was discussed further.

It does look like they vaired a little in their design. I'll do more research and see what I can find about it. I'll also get a look at these coils and see what is going on with them, I wonder if the two MW windings are linked at A2. I don't quite understand why there is 2 seperate windings on the one coil. There is also a seperate winding sandwiched between the two (MW & LW) coils that appears on the schematic

EF80TVVALVE · 20th Jun 2020, 11:36 am

A quick check with the multimeter shows that there are indeed two windings on the first coil. I've also attached the photo of the coil showing where the wires appear. It looks like the end of the first coil and beginning of the second coil come from the middle.

From that I've drawn up a rather crude diagram how the coil was originally connected from the photos I have, but I don't know the history of this set or if someone has worked on it before.

As for the LW coil, it has one end completely disconnected and has been since I had the set. The other end of the LW coil is also connected to A1.

The coil sandwiched between the two is connected to the volume varicap (which the other end connects to neg) and the other end again is loose

Herald1360 · 20th Jun 2020, 11:57 am

The sandwich filling will be the reaction (feedback) coil. Reaction was sometimes labelled as volume on early sets. The loose end probably goes to the detector anode.

B4 base triodes all had the same connection layout, so that's an easy check to do.

EF80TVVALVE · 20th Jun 2020, 5:02 pm

Thanks to everyone for the advice so far. I've come up with this incomplete schematic of what I can suss out using some photos, looking at what is here and some similar circuits. I've attached what I can work out so far, parts may be incorrect so please correct me if so. Still not sure about the coils, especially the LW which is currently only connected to Aerial 1.

PJL · 20th Jun 2020, 6:48 pm

The 'volume' will be a reaction control that should allow +ve feedback from A1 anode through a separate winding in the coil.
The inductor is the high impedance load for the regenerative detector fed through the intervalve transformer primary from the HT battery normally via a resistor with capacitor decoupling.
The other end of the secondary goes to the grid bias battery providing the bias for the A2 output valve.

How about a few pictures?

EF80TVVALVE · 20th Jun 2020, 8:08 pm

Thanks for that, I think I've just about completed the schematic, other than the question of the coils which I'm still unsure of. I've attached more photos, the front plate contains the tuining circuitry and the main chassis holding the capacitor to grid and intervalve transformer, along with the valve bases and HFC. As can be seen the reaction coil is sandwiched between the two, with the smaller coil at the bottom (this is the one with 2x seperate coils on one bobbin. The top coil is one single winding approx twice the size of the other.

EF80TVVALVE · 21st Jun 2020, 12:19 pm

Looking up a few other circuits and comparing it with the original coils schematic (the only thing that seems to available for the Double 2) I have drawn up a revised version of the coils. I think it may be that the first coil (2 windings on 1 bobbin) goes from Aerial 1 to Aerial 2 then the second winding from Aerial 2 to Aerial 3 where this joins the larger coil which connects from A3 to Neg.

This seems to be how it looks on the original schematic, although it isn't exactly clear with the way in which the connections are drawn up, when I first got this receiver it was connected differently which adds to the confusion. Looking at similar circuits it helps to confirm this. I'll try this circuit first and see where I get with it.

Another problem I have is that I don't know any of the voltages required for HT, Grid bias or Heaters. I would imagine the valves are 2v as were common at the time. I was thinking of making up the GB and HT batteries with various taps to work out a good HT and GB voltage without damaging the set and overloading it.

I also need to replace the intervalve transformer in which one winding is O/C, but I will see what I can find or get it rewound.

PJL · 21st Jun 2020, 3:11 pm

What valves are in it? The A1 valve has no bias so it needs to be something designed for the job, a PM1HF maybe. The output valve can be anything as you are providing both bias and the HT for it, PM2A would do.

EF80TVVALVE · 21st Jun 2020, 3:36 pm

The valves are branded Double Two and they must use their own numbers as I can't find any information on them other than an example the valve museum has. The first valve is LX230 and the output valve is HX210. They must be equivalents to something available at the time, but what I don't know.

PJL · 21st Jun 2020, 4:33 pm

HX210 http://www.r-type.org/exhib/aaq0497.htm - this will be the HF valve A1
LX230 http://www.r-type.org/exhib/aaq0180.htm - this will be the output valve A2

The higher filament current valve is the output...

EF80TVVALVE · 21st Jun 2020, 9:28 pm

Thanks for that, I've now fitted that one to the output instead. As I say I only have some photographs of how it once was and the valves were fitted reverse in those too. It's now pretty much reassembled although I will need to find a replacement intervalve tx or have this one rewound. I believe the current one is a Sutra brand which were made in France.

19th Jun 2020, 10:26 pm	#1
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Double 2 radio Hi All, Does anyone have a schematic or even an example of one of these small two valve 'double two' radio receivers. I'm attempting to find some information in order to get mine back in one piece but I'm not too familiar with these early sets to work from nothing and there seems to be very little information on them. Failing that if anyone would like to solve the puzzle and have a go then let me know and I can send it to a member who would be able to get it going again.

20th Jun 2020, 7:52 am	#2
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Double 2 radio I assume you dont mean this Regentone Double two https://www.radiomuseum.org/r/regentone_double_two.html Mike

20th Jun 2020, 8:53 am	#3
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,865	Re: Double 2 radio The Double 2 Logo was used by Hustler Simpson and Web around 1930. There was an an article in one of the Radio Magazines but I cannot remember which one. A Double 2 was the cover story on the BVWS magazine VOL 16 No 2 https://www.bvws.org.uk/publications...letin_16_2.pdf Do you have the same set? or another model. The usual brand name for H S W was Aerodyne ISTR. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 20th Jun 2020 at 9:07 am.

20th Jun 2020, 10:05 am	#4
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Hi, Mike is right, the set is the one made by Hustler Simpson and Webb. I have seen the cover story on the BVWS and it is the same model, but with some differences. One difference is the resistor from the tuning variable capacitor to grid also has a capacitor in parallel on mine. The MW coil also seems to have two seperate windings from what I can measure, although I need to remove this and check properly as a lot of the connections are very dirty. Another difference is that mine doesn't have the resistor fitted from grid to cathode on the first valve. It is fairly easy to work out the 4 pin connections of the valves from looking inside the envelope so that is no problem. The bigger problem is the coil connections and differences I have from the small piece of schematic on the BVWS cover. I've looked at other 0-V-1 circuits and whilst none are exactly the same the will help somewhat with getting some of it together. I've never found a schematic for the double 2 so I don't even know if one exists, finding another set would be helpful but again I've never came across one, although I know that there must be at least two more out there somewhere!

20th Jun 2020, 10:18 am	#5
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,865	Re: Double 2 radio You often see that arrangement where the grid leak resistor is in Parallel with the Capacitor rather than the grid leak connecting to filament or cathode. Thats a classic grid leak detector. It could be the design in the article is anode bend detection and the detector is getting a small bias from the filament supply. It's not clear if the set is one of Normans own it looks as if he drew out the circuit or at least part of it for the cover. Did you look at the letters pages of the Bulletin over the next year or so? there were two letters in Vol 16 no3 and one especially mentions the "lack" of a grid leak resistor so it seems more than one arrangement. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 20th Jun 2020 at 10:31 am.

20th Jun 2020, 10:40 am	#6
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Hi Mike, Yes I did read the letters from the next issue although it may be worth me looking through more and seeing if it was discussed further. It does look like they vaired a little in their design. I'll do more research and see what I can find about it. I'll also get a look at these coils and see what is going on with them, I wonder if the two MW windings are linked at A2. I don't quite understand why there is 2 seperate windings on the one coil. There is also a seperate winding sandwiched between the two (MW & LW) coils that appears on the schematic

20th Jun 2020, 11:36 am	#7
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio A quick check with the multimeter shows that there are indeed two windings on the first coil. I've also attached the photo of the coil showing where the wires appear. It looks like the end of the first coil and beginning of the second coil come from the middle. From that I've drawn up a rather crude diagram how the coil was originally connected from the photos I have, but I don't know the history of this set or if someone has worked on it before. As for the LW coil, it has one end completely disconnected and has been since I had the set. The other end of the LW coil is also connected to A1. The coil sandwiched between the two is connected to the volume varicap (which the other end connects to neg) and the other end again is loose Attached Thumbnails

20th Jun 2020, 11:57 am	#8
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Double 2 radio The sandwich filling will be the reaction (feedback) coil. Reaction was sometimes labelled as volume on early sets. The loose end probably goes to the detector anode. B4 base triodes all had the same connection layout, so that's an easy check to do. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

20th Jun 2020, 5:02 pm	#9
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Thanks to everyone for the advice so far. I've come up with this incomplete schematic of what I can suss out using some photos, looking at what is here and some similar circuits. I've attached what I can work out so far, parts may be incorrect so please correct me if so. Still not sure about the coils, especially the LW which is currently only connected to Aerial 1. Attached Thumbnails

20th Jun 2020, 6:48 pm	#10
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Double 2 radio The 'volume' will be a reaction control that should allow +ve feedback from A1 anode through a separate winding in the coil. The inductor is the high impedance load for the regenerative detector fed through the intervalve transformer primary from the HT battery normally via a resistor with capacitor decoupling. The other end of the secondary goes to the grid bias battery providing the bias for the A2 output valve. How about a few pictures?

20th Jun 2020, 8:08 pm	#11
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Thanks for that, I think I've just about completed the schematic, other than the question of the coils which I'm still unsure of. I've attached more photos, the front plate contains the tuining circuitry and the main chassis holding the capacitor to grid and intervalve transformer, along with the valve bases and HFC. As can be seen the reaction coil is sandwiched between the two, with the smaller coil at the bottom (this is the one with 2x seperate coils on one bobbin. The top coil is one single winding approx twice the size of the other. Attached Thumbnails

21st Jun 2020, 12:19 pm	#12
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Looking up a few other circuits and comparing it with the original coils schematic (the only thing that seems to available for the Double 2) I have drawn up a revised version of the coils. I think it may be that the first coil (2 windings on 1 bobbin) goes from Aerial 1 to Aerial 2 then the second winding from Aerial 2 to Aerial 3 where this joins the larger coil which connects from A3 to Neg. This seems to be how it looks on the original schematic, although it isn't exactly clear with the way in which the connections are drawn up, when I first got this receiver it was connected differently which adds to the confusion. Looking at similar circuits it helps to confirm this. I'll try this circuit first and see where I get with it. Another problem I have is that I don't know any of the voltages required for HT, Grid bias or Heaters. I would imagine the valves are 2v as were common at the time. I was thinking of making up the GB and HT batteries with various taps to work out a good HT and GB voltage without damaging the set and overloading it. I also need to replace the intervalve transformer in which one winding is O/C, but I will see what I can find or get it rewound. Attached Thumbnails

21st Jun 2020, 3:11 pm	#13
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Double 2 radio What valves are in it? The A1 valve has no bias so it needs to be something designed for the job, a PM1HF maybe. The output valve can be anything as you are providing both bias and the HT for it, PM2A would do.

21st Jun 2020, 3:36 pm	#14
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio The valves are branded Double Two and they must use their own numbers as I can't find any information on them other than an example the valve museum has. The first valve is LX230 and the output valve is HX210. They must be equivalents to something available at the time, but what I don't know.

21st Jun 2020, 4:33 pm	#15
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Double 2 radio HX210 http://www.r-type.org/exhib/aaq0497.htm - this will be the HF valve A1 LX230 http://www.r-type.org/exhib/aaq0180.htm - this will be the output valve A2 The higher filament current valve is the output...

21st Jun 2020, 9:28 pm	#16
EF80TVVALVE Octode Join Date: Feb 2010 Location: Leicester, UK. Posts: 1,433	Re: Double 2 radio Thanks for that, I've now fitted that one to the output instead. As I say I only have some photographs of how it once was and the valves were fitted reverse in those too. It's now pretty much reassembled although I will need to find a replacement intervalve tx or have this one rewound. I believe the current one is a Sutra brand which were made in France.