AC/DC Electron-X info needed - UK Vintage Radio Repair and Restoration Discussion Forum

Paul Mathew · 2nd Jun 2019, 9:58 am

I'm looking for more info on this set. Tubes identified are dl94 , dk91 ,df91 , 1T4 ? , S5 ? The rectifier tube is missing, but looks like an 80 socket? Any info and schematic would be great!

Herald1360 · 2nd Jun 2019, 5:03 pm

The valves listed with 1S5 as missing/unknown would make sense for a 5 valve set with RF stage. The types listed have a mix of European and American type numbers though equivalents for each exist in the other ranges.

The valve base shown looks more like B4 than UX4, so 80 is not a likely rectifier.

When you say AC/DC, do you mean AC/Battery? Does the set have a mains transformer? Providing the rectifier heater supply would be interesting if this is a set designed to run from AC or DC mains.

Paul Mathew · 2nd Jun 2019, 8:19 pm

Thanks for the feedback. I'm asking on behalf of a friend not on the forum, so don't have the set on hand, but will revert. Regards, Paul

Mike. Watterson · 3rd Jun 2019, 3:44 pm

For Southern African market? Maybe made by Supersonic (originally Rhodesia). No connection with current USA Supersonic products.
This is the D11, we presume there was a D1 to D10. It did have an optional mains supply,.
https://www.radiomuseum.org/r/mullard_d11.html
This is all I was able to find out about them:
https://www.radiomuseum.org/dsp_hers...ompany_id=4378
Most of the 50mA type battery valves have exact UK/Mullard/Philips and USA equivalents. Often Mazda too.

I think almost all the MW stations are South African abbreviations. Also no LW, but regular SW and Tropical bands is very typical sub-Saharan Africa.

Mike. Watterson · 3rd Jun 2019, 6:14 pm

All the same valves, all originally 1940 RCA.
DK91 = 1R5 = X17 = 1C1 , DF91 = 1T4= W17 = 1F3, DAF91 = 1S5 = ZD17 = 1FD9, DL94 = 3V4 = N19 = 1P11.
The East European & Russian ones are not quite the same, perhaps 1.2V rather than 1.4V. The Japanese ones are also copies of the RCA.
Originally all had nickel filaments. The Philips (Mullard) 25mA series versions were tungsten and later adopted in USA. I'm not sure if eventually the 50mA versions were later using tungsten. The first 1.4V (all dry) tubes were the Octal & Loctal Sylvania in 1938, copied in UK on Mazda Octal and P8 edge bases in 1939. RCA miniaturised them.

The rectifier is likely a B4 base and I'd imagine there is a transformer for its heater. Normally the rectifier would be the metal type and a BIG dropper for 6.8V series 50mA (nominal 7.5V battery) from the nominal 90V supply. There are a few battery sets with transformers and EZ4x rectifier valves, but most have metal rectifiers except in USA where the 115V heater rectifier valve was used for HT.

There are a few mains / battery sets with parallel filaments, but uncommon other than models for German (and derived markets) as they used NiCd to regulate the LT (DEAC). This is because the original 1940s Telefunken battery valves (low profile metal Y8) all had different filament currents depending on function so series operation wasn't possible.

2nd Jun 2019, 9:58 am	#1
Paul Mathew Pentode Join Date: Jan 2014 Location: Cape Town, South Africa Posts: 214	AC/DC Electron-X info needed I'm looking for more info on this set. Tubes identified are dl94 , dk91 ,df91 , 1T4 ? , S5 ? The rectifier tube is missing, but looks like an 80 socket? Any info and schematic would be great! Attached Thumbnails

2nd Jun 2019, 5:03 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: AC/DC Electron-X info needed The valves listed with 1S5 as missing/unknown would make sense for a 5 valve set with RF stage. The types listed have a mix of European and American type numbers though equivalents for each exist in the other ranges. The valve base shown looks more like B4 than UX4, so 80 is not a likely rectifier. When you say AC/DC, do you mean AC/Battery? Does the set have a mains transformer? Providing the rectifier heater supply would be interesting if this is a set designed to run from AC or DC mains. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

2nd Jun 2019, 8:19 pm	#3
Paul Mathew Pentode Join Date: Jan 2014 Location: Cape Town, South Africa Posts: 214	Re: AC/DC Electron-X info needed Thanks for the feedback. I'm asking on behalf of a friend not on the forum, so don't have the set on hand, but will revert. Regards, Paul

3rd Jun 2019, 3:44 pm	#4
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: AC/DC Electron-X info needed For Southern African market? Maybe made by Supersonic (originally Rhodesia). No connection with current USA Supersonic products. This is the D11, we presume there was a D1 to D10. It did have an optional mains supply,. https://www.radiomuseum.org/r/mullard_d11.html This is all I was able to find out about them: https://www.radiomuseum.org/dsp_hers...ompany_id=4378 Most of the 50mA type battery valves have exact UK/Mullard/Philips and USA equivalents. Often Mazda too. I think almost all the MW stations are South African abbreviations. Also no LW, but regular SW and Tropical bands is very typical sub-Saharan Africa.

3rd Jun 2019, 6:14 pm	#5
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: AC/DC Electron-X info needed All the same valves, all originally 1940 RCA. DK91 = 1R5 = X17 = 1C1 , DF91 = 1T4= W17 = 1F3, DAF91 = 1S5 = ZD17 = 1FD9, DL94 = 3V4 = N19 = 1P11. The East European & Russian ones are not quite the same, perhaps 1.2V rather than 1.4V. The Japanese ones are also copies of the RCA. Originally all had nickel filaments. The Philips (Mullard) 25mA series versions were tungsten and later adopted in USA. I'm not sure if eventually the 50mA versions were later using tungsten. The first 1.4V (all dry) tubes were the Octal & Loctal Sylvania in 1938, copied in UK on Mazda Octal and P8 edge bases in 1939. RCA miniaturised them. The rectifier is likely a B4 base and I'd imagine there is a transformer for its heater. Normally the rectifier would be the metal type and a BIG dropper for 6.8V series 50mA (nominal 7.5V battery) from the nominal 90V supply. There are a few battery sets with transformers and EZ4x rectifier valves, but most have metal rectifiers except in USA where the 115V heater rectifier valve was used for HT. There are a few mains / battery sets with parallel filaments, but uncommon other than models for German (and derived markets) as they used NiCd to regulate the LT (DEAC). This is because the original 1940s Telefunken battery valves (low profile metal Y8) all had different filament currents depending on function so series operation wasn't possible.