Remote control of tuning late 1930's - UK Vintage Radio Repair and Restoration Discussion Forum

rontech · 10th Dec 2018, 3:53 pm

I have observed that a number of top range radiograms in the late 1930' had remote control options with an armchair push button unit. This was at the end of a captive cable of course.

They seemed to be combined with motorised tuning capacitors but I was wondering just how the electrical & mechanical systems worked. Eg did the row of selector buttons have a manufacturer defined set of stations, or could the user "program" in some way the specific wavelength for each button?

For the manufacturer set stations I could envisage for example a set of microswitches riding on a detent wheel mounted on the tuning capacitor shaft.

Otherwise I am at a loss and would love know how the arrangements worked.

G6Tanuki · 10th Dec 2018, 4:04 pm

The usual "motorised" tuning used mechanical, user-settable stops on a disc which tripped a contact when the stop got to the right place, disconnecting the motor (and frequently putting a short across the motor to provide regenerative braking so it came to a stop promptly). Pressing the tune-button tripped a relay and re-energised the motor so it moved the disc round to the next stop. if you were lucky your radio automatically reversed when it got to the end of the waveband.

The ~programming~ was usually by way of loosening a screw on a particular stop, tuning the station manually then tightening the screw. A similar though manually-turned idea was implemented as "flick" settings on many WWII-era military radios.

Frequency-drift as components aged and the set warmed up could be an issue - some of the posher models used a discriminator and a reactance-valve to provide AFC to overcome this.

[I remember that there were also a couple of US models where the auto-tune was done using manufacturer-programmed discs with holes: the right disc for your town/city would be fitted by the supplying dealer. Understandably, given the number of discs needed in the US, where there were many more radio-stations operating than we ever had in the UK, the idea never caught on. I vaguely recall something about a lawsuit where the operators of some stations sued the radio-manufacturer in question because they had taken bribes from other station-operators not to include the 'competition' on the pre-programmed station-discs. This was the 1930s, shades of Eliot Ness and Al Capone!]

Mike. Watterson · 10th Dec 2018, 6:10 pm

There was also at least one 1930s Philco with Wireless remote control.

10th Dec 2018, 3:53 pm	#1
rontech Heptode Join Date: Jun 2017 Location: Southport, Merseyside, UK. Posts: 646	Remote control of tuning late 1930's I have observed that a number of top range radiograms in the late 1930' had remote control options with an armchair push button unit. This was at the end of a captive cable of course. They seemed to be combined with motorised tuning capacitors but I was wondering just how the electrical & mechanical systems worked. Eg did the row of selector buttons have a manufacturer defined set of stations, or could the user "program" in some way the specific wavelength for each button? For the manufacturer set stations I could envisage for example a set of microswitches riding on a detent wheel mounted on the tuning capacitor shaft. Otherwise I am at a loss and would love know how the arrangements worked. __________________ Time flies like an arrow, fruit flies like a banana

10th Dec 2018, 4:04 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Remote control of tuning late 1930's The usual "motorised" tuning used mechanical, user-settable stops on a disc which tripped a contact when the stop got to the right place, disconnecting the motor (and frequently putting a short across the motor to provide regenerative braking so it came to a stop promptly). Pressing the tune-button tripped a relay and re-energised the motor so it moved the disc round to the next stop. if you were lucky your radio automatically reversed when it got to the end of the waveband. The ~programming~ was usually by way of loosening a screw on a particular stop, tuning the station manually then tightening the screw. A similar though manually-turned idea was implemented as "flick" settings on many WWII-era military radios. Frequency-drift as components aged and the set warmed up could be an issue - some of the posher models used a discriminator and a reactance-valve to provide AFC to overcome this. [I remember that there were also a couple of US models where the auto-tune was done using manufacturer-programmed discs with holes: the right disc for your town/city would be fitted by the supplying dealer. Understandably, given the number of discs needed in the US, where there were many more radio-stations operating than we ever had in the UK, the idea never caught on. I vaguely recall something about a lawsuit where the operators of some stations sued the radio-manufacturer in question because they had taken bribes from other station-operators not to include the 'competition' on the pre-programmed station-discs. This was the 1930s, shades of Eliot Ness and Al Capone!]

10th Dec 2018, 6:10 pm	#3
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Remote control of tuning late 1930's There was also at least one 1930s Philco with Wireless remote control.