Oldest radio with push-pull output? - UK Vintage Radio Repair and Restoration Discussion Forum

saddlestone-man · 18th Nov 2018, 9:36 pm

Hello All

I was wondering which UK manufacturer produced the first ever radio with a push-pull audio output stage. There were a few portables with QPP outputs in the mid-1930s, but were there mains radios with push-pull earlier than this?

Best rgds. Stef.

Nuvistor · 18th Nov 2018, 9:46 pm

This one was 1937.

http://www.thevalvepage.com/radios/f...02AC/502AC.htm

Paul_RK · 18th Nov 2018, 9:47 pm

Quite a few, I expect. The first RGD in 1929 had push-pull output:

http://www.rgd.org.uk/rgd1929_1934.htm

It wouldn't surprise me if Dynatron beat them to it.

Paul

Herald1360 · 18th Nov 2018, 11:44 pm

I suspect you could go back to the mid '20s probably in one of the more expensive American offerings. The technology using audio driver and output transformers was certainly available.

Edit:

Wikipedia mentions the 1924 RCA "Radiola 3" as perhaps the first commercial offering, though the principle was known even earlier.

ukcol · 19th Nov 2018, 9:41 am

I can't answer your exact question but P_P was definitely around in the 20s.

My maternal great grandfather Herman Kloss was a classical pianist and professor of music. He had his own music school in London "Kloss' School of Music".

I mention him because of his other interests. I remember my mother telling me that he designed and built an automatic thermostatically operated window for his greenhouse and that he "invented" push-pull in radio in the early 1920s.. My mother had no knowledge of radio and so he must have made a push-pull system, but "invented" is of course highly unlikely.

Nuvistor · 19th Nov 2018, 10:21 am

A bit off topic, I have a bit of a soft spot for the Ferguson 502 or 503, not sure which, it’s a long time ago. It was our home radio, in the 50’s, my dad would have got it second hand and repaired it.
In the late 50’s he removed it from its cabinet and installled in in a radiogram cabinet bought from the adverts in PW, fitted a three speed record player and we had a radio gram.

It’s called up cycling now, then it was make do and mend.

lesmw0sec · 19th Nov 2018, 10:35 am

I once had a battery driven Pye set which had a push-pull o/p stage, using a double pentode in one envelope. It was referred to a 'Quiescent push-pull' from which I expect it was biased close to class B. The quality was excellent though.

Herald1360 · 19th Nov 2018, 12:17 pm

I wonder if any of the sets sold by battery manufacturers had QPP outputs?

TonyDuell · 19th Nov 2018, 1:24 pm

I don't know if it's QPP, but the EverReady Sky Monarch (both the AM-only and the AM/FM models) had push-pull output stages. They were battery-powered table radios (not the normal portable-style set). When I first saw the circuit of the AM version in R&TVS I joked that 'Ever Ready sold the batteries for this set, is that a coincidence'

kalee20 · 19th Nov 2018, 1:41 pm

And the Ever Ready Sky Emperor - also P-P output with DL96's - had a 'battery economiser' switch, which powered-down half the filament on the DL96's while at the same time increasing the back-bias resistor.

Who and when did the push-pull inventing? It's a brilliantly elegant scheme!

Nuvistor · 19th Nov 2018, 2:06 pm

Page 629 WW 13th June 1928, the article shows a circuit and gives a patent number to a Push Pull circuit dated 1915, not named as such but from the diagram obviously is.

https://www.americanradiohistory.com...ld-1928-06.pdf

Argus25 · 19th Nov 2018, 2:30 pm

Often radios in the 1920's era had additional add on amplifiers. The Samson company in the mid 1920's made some very nice transformers & chokes for push pull amplifiers for radios. I made a push pull amp from some of these transformers made in 1927:

http://worldphaco.com/uploads/UX-171...amplifier..pdf

There was extensive documentation in the RCA Radiotron designers' handbook in 1932 on the operation of push pull amplifiers. So probably the early 1920's was the time it was becoming popular, especially in battery sets where the energy savings of class B and the lower weight output transformers also helped too.

ukcol · 19th Nov 2018, 3:14 pm

There were special valves developed for class B2 Push Pull like the PD220 but that wasn't on the scene until 1933.

peter_scott · 19th Nov 2018, 3:16 pm

I'm not sure of the date of this one but I would suspect perhaps 1932/33.

Valves are MM4V, 354V, 2 x PM256, DW3
According to the Valve Museum the PM256 appears in a Scott-Taggart advert in March 1927.

Peter

18th Nov 2018, 9:36 pm	#1
saddlestone-man Hexode Join Date: Mar 2009 Location: Cirencester, Gloucestershire, UK. Posts: 391	Oldest radio with push-pull output? Hello All I was wondering which UK manufacturer produced the first ever radio with a push-pull audio output stage. There were a few portables with QPP outputs in the mid-1930s, but were there mains radios with push-pull earlier than this? Best rgds. Stef.

18th Nov 2018, 9:46 pm	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Oldest radio with push-pull output? This one was 1937. http://www.thevalvepage.com/radios/f...02AC/502AC.htm __________________ Frank

18th Nov 2018, 9:47 pm	#3
Paul_RK Dekatron Join Date: Nov 2003 Location: Fakenham, Norfolk, UK. Posts: 4,259	Re: Oldest radio with push-pull output? Quite a few, I expect. The first RGD in 1929 had push-pull output: http://www.rgd.org.uk/rgd1929_1934.htm It wouldn't surprise me if Dynatron beat them to it. Paul

18th Nov 2018, 11:44 pm	#4
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Oldest radio with push-pull output? I suspect you could go back to the mid '20s probably in one of the more expensive American offerings. The technology using audio driver and output transformers was certainly available. Edit: Wikipedia mentions the 1924 RCA "Radiola 3" as perhaps the first commercial offering, though the principle was known even earlier. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

19th Nov 2018, 9:41 am	#5
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: Oldest radio with push-pull output? I can't answer your exact question but P_P was definitely around in the 20s. My maternal great grandfather Herman Kloss was a classical pianist and professor of music. He had his own music school in London "Kloss' School of Music". I mention him because of his other interests. I remember my mother telling me that he designed and built an automatic thermostatically operated window for his greenhouse and that he "invented" push-pull in radio in the early 1920s.. My mother had no knowledge of radio and so he must have made a push-pull system, but "invented" is of course highly unlikely.

19th Nov 2018, 10:21 am	#6
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Oldest radio with push-pull output? A bit off topic, I have a bit of a soft spot for the Ferguson 502 or 503, not sure which, it’s a long time ago. It was our home radio, in the 50’s, my dad would have got it second hand and repaired it. In the late 50’s he removed it from its cabinet and installled in in a radiogram cabinet bought from the adverts in PW, fitted a three speed record player and we had a radio gram. It’s called up cycling now, then it was make do and mend. __________________ Frank

19th Nov 2018, 10:35 am	#7
lesmw0sec Octode Join Date: Jul 2009 Location: Carmel, Llannerchymedd, Anglesey, UK. Posts: 1,509	Re: Oldest radio with push-pull output? I once had a battery driven Pye set which had a push-pull o/p stage, using a double pentode in one envelope. It was referred to a 'Quiescent push-pull' from which I expect it was biased close to class B. The quality was excellent though.

19th Nov 2018, 12:17 pm	#8
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Oldest radio with push-pull output? I wonder if any of the sets sold by battery manufacturers had QPP outputs? __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

19th Nov 2018, 1:24 pm	#9
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,219	Re: Oldest radio with push-pull output? I don't know if it's QPP, but the EverReady Sky Monarch (both the AM-only and the AM/FM models) had push-pull output stages. They were battery-powered table radios (not the normal portable-style set). When I first saw the circuit of the AM version in R&TVS I joked that 'Ever Ready sold the batteries for this set, is that a coincidence'

19th Nov 2018, 1:41 pm	#10
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: Oldest radio with push-pull output? And the Ever Ready Sky Emperor - also P-P output with DL96's - had a 'battery economiser' switch, which powered-down half the filament on the DL96's while at the same time increasing the back-bias resistor. Who and when did the push-pull inventing? It's a brilliantly elegant scheme!

19th Nov 2018, 2:06 pm	#11
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Oldest radio with push-pull output? Page 629 WW 13th June 1928, the article shows a circuit and gives a patent number to a Push Pull circuit dated 1915, not named as such but from the diagram obviously is. https://www.americanradiohistory.com...ld-1928-06.pdf __________________ Frank

19th Nov 2018, 2:30 pm	#12
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Oldest radio with push-pull output? Often radios in the 1920's era had additional add on amplifiers. The Samson company in the mid 1920's made some very nice transformers & chokes for push pull amplifiers for radios. I made a push pull amp from some of these transformers made in 1927: http://worldphaco.com/uploads/UX-171...amplifier..pdf There was extensive documentation in the RCA Radiotron designers' handbook in 1932 on the operation of push pull amplifiers. So probably the early 1920's was the time it was becoming popular, especially in battery sets where the energy savings of class B and the lower weight output transformers also helped too.

19th Nov 2018, 3:14 pm	#13
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: Oldest radio with push-pull output? There were special valves developed for class B2 Push Pull like the PD220 but that wasn't on the scene until 1933.

19th Nov 2018, 3:16 pm	#14
peter_scott Dekatron Join Date: May 2003 Location: Edinburgh, UK. Posts: 3,274	Re: Oldest radio with push-pull output? I'm not sure of the date of this one but I would suspect perhaps 1932/33. Valves are MM4V, 354V, 2 x PM256, DW3 According to the Valve Museum the PM256 appears in a Scott-Taggart advert in March 1927. Peter Attached Thumbnails __________________ http://www.nostalgiatech.co.uk https://www.youtube.com/c/PeterScott/videos Last edited by peter_scott; 19th Nov 2018 at 3:22 pm.