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Early 3 valve radio id please

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Early 3 valve radio id please

Post by FIXITNOW2003 » Thu Mar 24, 2016 8:46 am

picked up this sadly no valves and missing a side plus the speaker has been replaced its a Early 3 valve set, it has a Marconi license plate in the bottom so I am guessing manufacture made rather than kit built
can any one id it please
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Re: Early 3 valve radio id please

Post by Michael Watterson » Tue Apr 05, 2016 11:30 pm

Det Triode
Det or LF triode audio amp
output audio triode.
(the two audio transformers give it away).

Very many 2V valves will work, or 3 x 1j29b Russian rod tubes in triodised connection (1.2V NiMH LT), but only connect half the filament or gain is x2 and then too high. Possibly reduce gain with a 4.7 Ohm resistor in each f- lead, or larger if you want to run off 2V lead Acid.

It probably used a tapped -9V GB pack for the two audio valves, at different taps.

It's not that early as it's dynamic not moving iron cone speaker. Likely most sets had SG RF preamp when that was made, so maybe 1931 to 1934. For strong signal areas.

I don't recognise it. It might have been any cycle shop making them. (Currys started as cycle shop charging the 2V LT batteries).

 
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Re: Early 3 valve radio id please

Post by FIXITNOW2003 » Wed Apr 06, 2016 7:38 am

cheers for that
the speaker is not original as its a modern 4 ohm with a o/p tx added to match it somewhere in its distance past

 
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Re: Early 3 valve radio id please

Post by Brianc » Wed Apr 06, 2016 11:18 am

The original speaker would have been a moving iron type as the hole in the centre of the fretwork is for the adjustment screw to centre the moving armature to the centre of the gap between the pole pieces as the DC through the output valve flowing through the speaker would bias it to one or other side of the gap.
Micheal is probably correct in it being a "cycle shop" product from the late 1920s to early 1930s.

 
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Re: Early 3 valve radio id please

Post by Michael Watterson » Wed Apr 06, 2016 7:42 pm

Brianc wrote:The original speaker would have been a moving iron type as the hole in the centre of the fretwork is for the adjustment screw to centre the moving armature to the centre of the gap between the pole pieces.


Ah rats, I missed that.


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