Loewe Radio Zwergsuper Opta 3516GW - UK Vintage Radio Repair and Restoration Discussion Forum

bobskie · 30th Jul 2017, 9:27 pm

I picked up this seemingly rather rare(in this country at least) radio in my local area today. Its a German made radio from just after the war with a very basic design to show for it. The radio is missing a knob,has another (or two?) incorrect knobs, missing glass and has several woodworm exit holes. Upon opening it there is a tear in the speaker and wires loose in several locations, somebody has also replaced the electrolytic cans at some point though the replacements are also German so this could be an older repair. I promptly treated it with some cuprinol 5 in 1 woodworm killer from the inside, the woodworm holes suggest the woodworm is probably gone but you can't be too careful. I have also taken a note of how many holes are on each side to ensure the infestation is gone. Does anyone have a full service manual for this radio? I have downloaded all the documents from radiomuseum already but would be nice to have the complete manual(even if in German). Its a nice little radio with an interesting background and should provide a decent challenge for restoration. I also must ask is this ok to use on mains voltage here or will I need some sort of transformer? The previous owner seems to suggest it was working OK here a few years back but I don't know how fussy it will be. If anyone has any further interesting information feel free to share. I will update this thread with the process as I go along. I have attached some pictures also.

music-centre · 30th Jul 2017, 10:04 pm

Must be a rare set - the dial is unusual, hardly any UK stations shown but its got Welsh regional on MW! - what would the London shown on LW next to Droitwich be?
Steve.

bobskie · 31st Jul 2017, 10:50 am

Yes I think it is quite rare, I can't find many mentions of it online. I'm quite looking forward to the restoration! I feel as if I should take a scan of the dial since it's just paper incase it is damaged or if someone else needs one but unfortunately I don't have a scanner, perhaps an opportunity for a purchase?

bluepilot · 31st Jul 2017, 11:18 am

Elektrotanya has the circuit diagram. Just search for Loewe 3516.

Berlin-RIAS on the dial makes it clearly post-war. RIAS is Rundfunk Im Amerikanischen Sektor, broadcasting in the American sector.

The GW means Gleichstrom Wechselstrom, i.e. AC/DC (well DC/AC to be exact) so I guess it won't have a transformer. It looks like a 230V set so probably OK to use it in the UK but you might want to use a transformer anyway just to be safe.

bobskie · 31st Jul 2017, 11:57 am

Thanks for the information, it does actually have a transformer on the chassis though I don't know what for, the mains doesn't seem to be connected to it. There is an audio transformer on the speaker so it can't be for that. AC/DC means live chassis so I better be careful.

Cameron

bluepilot · 31st Jul 2017, 12:04 pm

Quote:

Originally Posted by bobskie

it does actually have a transformer on the chassis though I don't know what for, the mains doesn't seem to be connected to it.

I had a look at the circuit diagram. Like I said there's no mains transformer. However the power supply uses a choke for smoothing rather than a resistor so maybe its actually that.

bobskie · 31st Jul 2017, 5:49 pm

Yes that's probably what it is then, it will probably be OK on 240v in that case. It doesn't have any continuity between the live and neutral on the plug so that's not a great sign, but at least it's not a transformer.

bobskie · 31st Jul 2017, 7:46 pm

A very strange situation has occured, I had a look at the circuit diagram and I noticed this radio is supposed to have 4 valves! The uy11 appears to have been replaced by this strange object I have attached pictures of. What is it? I'm assuming some sort of valve replacer. I'm a bit worried about this set somebody has been in it messing around. Wires and components keep falling off and some I don't know where they even came from! I'll have to study the wiring diagram carefully. I wonder why this is happening too? It's like a really weak solder has been used. I may need to replace a lot of weak wires too they seem to be breaking in half in some places.

ms660 · 31st Jul 2017, 8:31 pm

It's a metal rectifier.

Lawrence,

bluepilot · 31st Jul 2017, 8:40 pm

Quote:

Originally Posted by bobskie

The uy11 appears to have been replaced by this strange object

It looks like a selenium rectifier. Rectifier valves often got replaced by them so nothing really unusual. It should be easy to get a UY11 if you want to restore the original state. However it does mean that the radio has been "got at" so keep an eye open for any other changes. If wires have fallen off you'll need to go through the circuit to find out what should be where. No continuity between live and neutral isn't necessarily a bad sign. You'd need the radio to be powered for the valves to conduct although it's possible that the rectifier is defective.

bobskie · 31st Jul 2017, 8:43 pm

Quote:

Originally Posted by ms660

It's a metal rectifier.

Lawrence,

So is it safe to assume that's all wired up ok? It's a rectifier valve it's replacing so I presume it should theoretically work and I cannot find a single correct valve for it. I hope the circuit diagrams aren't deviated from too much in other parts of the circuit. I won't be working on the wiring for a while though I want to get my 12v build working first. I have just been repairing the speaker in other news, here is a picture. A bit of excess glue but it looks not bad so far. I have used a piece of coffee filter and PVA glue. I also had to secure the speaker edges down again as the glue was coming off hence the clothes pegs. I will also need to find a replacement dust cover for it.

TrevorG3VLF · 31st Jul 2017, 9:06 pm

If it is AC/DC set, then the valve heaters are likely to be in series and removing any valve will stop any connection between line and neutral.
So, how did it work?

ms660 · 31st Jul 2017, 9:09 pm

Usually a metal rectifier will have a + stamped at or near one of the connecting tags, the + would denote the cathode, the cathode should be connected to the HT choke and the reservoir capacitor according to a schematic I'm looking at. Sometimes they can go a bit tired, resulting in low HT, most folks would normally replace them with a silicon job and a limiting resistor.

Lawrence.

bluepilot · 31st Jul 2017, 9:18 pm

Quote:

Originally Posted by TrevorG3VLF

If it is AC/DC set, then the valve heaters are likely to be in series and removing any valve will stop any connection between line and neutral.
So, how did it work?

The UY11 heater is not in series with the heaters of the other three valves, so no problem with removing it in that respect.

bobskie · 31st Jul 2017, 10:19 pm

It seems as if it should work, and I expect it probably did at some point. Would it be possible to replace this with some other rectifier valve? Are they all fairly similar? I have a big box of valves(mostly 50s) I could have a look through to keep this all valve based. What type of silicon rectifier would I use if I were to go that way? A link would be handy

. Or perhaps I should locate the correct valve and restore the radio to it's originality, the valve holder is still in place after all but that would be a challenge in itself.

Thanks for the help everyone.

PJL · 31st Jul 2017, 10:21 pm

Y8A valves are exclusively German and not very common. You could try ebay.de I guess. Alternative would be to make an adaptor for a UY85.

bobskie · 31st Jul 2017, 10:28 pm

Thats definitely an option, according to my list I have 3 of those in stock. That seems like it could be the way to go I don't think I'll have much luck finding the correct valve.

bluepilot · 1st Aug 2017, 7:45 am

Ebay.de has a load of UY11s on offer. Alternatively there is an adaptor for a UY82. Search for "UY 11 Zwischensockel". They don't indicate delivery to the UK but usually they will if you ask. The supply of UY11s seems to have run out at some point after the war so they made adaptors. Probably the reason this one was replaced with a metal rectifier.

Alternatively if the metal rectifier is defective you could just use a silicon diode with a resistor in series. Something like a 1N4007.

bobskie · 1st Aug 2017, 8:18 am

Yes I found that adapter, that would probably make it easier. I have been recommended a few possible suppliers of this valve in the UK so I will try them first. It doesn't seem to be quite as hard to find as I first thought.

Cameron

ms660 · 1st Aug 2017, 8:29 am

If it was used on 220 volt mains then the total dropper resistor value for the valve heaters should have been increased when the metal rectifier was fitted, if so then you will need to take that into account if replacing the metal rectifier with a valve rectifier, according to the schematic I'm looking at.

Lawrence.

30th Jul 2017, 9:27 pm	#1
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Loewe Radio Zwergsuper Opta 3516GW I picked up this seemingly rather rare(in this country at least) radio in my local area today. Its a German made radio from just after the war with a very basic design to show for it. The radio is missing a knob,has another (or two?) incorrect knobs, missing glass and has several woodworm exit holes. Upon opening it there is a tear in the speaker and wires loose in several locations, somebody has also replaced the electrolytic cans at some point though the replacements are also German so this could be an older repair. I promptly treated it with some cuprinol 5 in 1 woodworm killer from the inside, the woodworm holes suggest the woodworm is probably gone but you can't be too careful. I have also taken a note of how many holes are on each side to ensure the infestation is gone. Does anyone have a full service manual for this radio? I have downloaded all the documents from radiomuseum already but would be nice to have the complete manual(even if in German). Its a nice little radio with an interesting background and should provide a decent challenge for restoration. I also must ask is this ok to use on mains voltage here or will I need some sort of transformer? The previous owner seems to suggest it was working OK here a few years back but I don't know how fussy it will be. If anyone has any further interesting information feel free to share. I will update this thread with the process as I go along. I have attached some pictures also. Attached Thumbnails

30th Jul 2017, 10:04 pm	#2
music-centre Heptode Join Date: Sep 2007 Location: Brentwood, Essex, UK. Posts: 687	Re: Loewe Radio Zwergsuper Opta 3516GW Must be a rare set - the dial is unusual, hardly any UK stations shown but its got Welsh regional on MW! - what would the London shown on LW next to Droitwich be? Steve.

31st Jul 2017, 10:50 am	#3
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW Yes I think it is quite rare, I can't find many mentions of it online. I'm quite looking forward to the restoration! I feel as if I should take a scan of the dial since it's just paper incase it is damaged or if someone else needs one but unfortunately I don't have a scanner, perhaps an opportunity for a purchase?

31st Jul 2017, 11:18 am	#4
bluepilot Heptode Join Date: Feb 2010 Location: Duffort, Gers, France Posts: 714	Re: Loewe Radio Zwergsuper Opta 3516GW Elektrotanya has the circuit diagram. Just search for Loewe 3516. Berlin-RIAS on the dial makes it clearly post-war. RIAS is Rundfunk Im Amerikanischen Sektor, broadcasting in the American sector. The GW means Gleichstrom Wechselstrom, i.e. AC/DC (well DC/AC to be exact) so I guess it won't have a transformer. It looks like a 230V set so probably OK to use it in the UK but you might want to use a transformer anyway just to be safe. __________________ Stuart The golden age is always yesterday - Asa Briggs Last edited by bluepilot; 31st Jul 2017 at 11:22 am. Reason: Added last paragraph

31st Jul 2017, 11:57 am	#5
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW Thanks for the information, it does actually have a transformer on the chassis though I don't know what for, the mains doesn't seem to be connected to it. There is an audio transformer on the speaker so it can't be for that. AC/DC means live chassis so I better be careful. Cameron

31st Jul 2017, 5:49 pm	#7
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW Yes that's probably what it is then, it will probably be OK on 240v in that case. It doesn't have any continuity between the live and neutral on the plug so that's not a great sign, but at least it's not a transformer.

31st Jul 2017, 7:46 pm	#8
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW A very strange situation has occured, I had a look at the circuit diagram and I noticed this radio is supposed to have 4 valves! The uy11 appears to have been replaced by this strange object I have attached pictures of. What is it? I'm assuming some sort of valve replacer. I'm a bit worried about this set somebody has been in it messing around. Wires and components keep falling off and some I don't know where they even came from! I'll have to study the wiring diagram carefully. I wonder why this is happening too? It's like a really weak solder has been used. I may need to replace a lot of weak wires too they seem to be breaking in half in some places. Attached Thumbnails Last edited by bobskie; 31st Jul 2017 at 7:48 pm. Reason: Forgot pictures!

31st Jul 2017, 8:31 pm	#9
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Loewe Radio Zwergsuper Opta 3516GW It's a metal rectifier. Lawrence,

31st Jul 2017, 9:06 pm	#12
TrevorG3VLF Rest in Peace Join Date: Apr 2011 Location: Matlock, Derbyshire, UK. Posts: 1,378	Re: Loewe Radio Zwergsuper Opta 3516GW If it is AC/DC set, then the valve heaters are likely to be in series and removing any valve will stop any connection between line and neutral. So, how did it work?

31st Jul 2017, 9:09 pm	#13
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Loewe Radio Zwergsuper Opta 3516GW Usually a metal rectifier will have a + stamped at or near one of the connecting tags, the + would denote the cathode, the cathode should be connected to the HT choke and the reservoir capacitor according to a schematic I'm looking at. Sometimes they can go a bit tired, resulting in low HT, most folks would normally replace them with a silicon job and a limiting resistor. Lawrence.

31st Jul 2017, 10:19 pm	#15
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW It seems as if it should work, and I expect it probably did at some point. Would it be possible to replace this with some other rectifier valve? Are they all fairly similar? I have a big box of valves(mostly 50s) I could have a look through to keep this all valve based. What type of silicon rectifier would I use if I were to go that way? A link would be handy . Or perhaps I should locate the correct valve and restore the radio to it's originality, the valve holder is still in place after all but that would be a challenge in itself. Thanks for the help everyone. Last edited by bobskie; 31st Jul 2017 at 10:31 pm.

31st Jul 2017, 10:21 pm	#16
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Loewe Radio Zwergsuper Opta 3516GW Y8A valves are exclusively German and not very common. You could try ebay.de I guess. Alternative would be to make an adaptor for a UY85.

31st Jul 2017, 10:28 pm	#17
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW Thats definitely an option, according to my list I have 3 of those in stock. That seems like it could be the way to go I don't think I'll have much luck finding the correct valve.

1st Aug 2017, 7:45 am	#18
bluepilot Heptode Join Date: Feb 2010 Location: Duffort, Gers, France Posts: 714	Re: Loewe Radio Zwergsuper Opta 3516GW Ebay.de has a load of UY11s on offer. Alternatively there is an adaptor for a UY82. Search for "UY 11 Zwischensockel". They don't indicate delivery to the UK but usually they will if you ask. The supply of UY11s seems to have run out at some point after the war so they made adaptors. Probably the reason this one was replaced with a metal rectifier. Alternatively if the metal rectifier is defective you could just use a silicon diode with a resistor in series. Something like a 1N4007. __________________ Stuart The golden age is always yesterday - Asa Briggs

1st Aug 2017, 8:18 am	#19
bobskie Hexode Join Date: Apr 2017 Location: Falkirk, Stirling, UK. Posts: 336	Re: Loewe Radio Zwergsuper Opta 3516GW Yes I found that adapter, that would probably make it easier. I have been recommended a few possible suppliers of this valve in the UK so I will try them first. It doesn't seem to be quite as hard to find as I first thought. Cameron

1st Aug 2017, 8:29 am	#20
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Loewe Radio Zwergsuper Opta 3516GW If it was used on 220 volt mains then the total dropper resistor value for the valve heaters should have been increased when the metal rectifier was fitted, if so then you will need to take that into account if replacing the metal rectifier with a valve rectifier, according to the schematic I'm looking at. Lawrence.