Supersonic Heterodyne radio 1920's. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

FERNSEH · 16th Mar 2018, 11:39 pm

Diodes were used as the mixer in television tuners. A 1N34 germanium diode in UHF tuners and a Mazda 6D2/EB91 double-diode in the Murphy V114 TV receiver. Don't know of any domestic radio receiver that ever employed a mixer diode.

DFWB.

Argus25 · 17th Mar 2018, 6:00 am

Wow ! What a great radio and worth every ounce of effort you are putting into fixing it.
I particularly like that engine turning finish on the variable capacitor frames.

Herald1360 · 17th Mar 2018, 9:27 am

Any chance of a complete front end circuit? Or are the coils etc buried inside a proprietary unit?

A redraw with signal flow left to right would be the icing on the cake.... it can be tricky driving backwards!

vinrads · 17th Mar 2018, 11:37 am

OK some more pictures , and re drawn cct Mick.

vinrads · 17th Mar 2018, 1:43 pm

For those that are interested , a picture of the chassis in it's original cabinet .it's 38.5" x 12.5" the far right knob is a mains switch and above a led on the two volts supply above that a mains ind neon , these were to fill holes that were already there. Mick.

Herald1360 · 17th Mar 2018, 11:39 pm

Now I'm more confused. Frame tuning on the oscillator valve? I think of a frame as a large aerial coil used instead of a wire aerial. Osc tuning on 1st IFT? Are the two coils in the oscillator coupler unit the oscillator feedback HFtransformer or is one in the oscillator circuit and the other in the mixer circuit?

Somewhere there has to be oscillator coupling into the RF/mixer valve for the IF to be present in its anode circuit.

+2V and -2V are shown- which is actually signal ground? Probably but not necessarily common with HT-.

As things stand, this appears to be a set which works in spite of how it's connected up, not because of it!

Mr Moose · 18th Mar 2018, 1:08 am

Hello,
In 1927 Bowyer-Lowe produced a superhetrodyne constructors kit, containing three IF transformers, one filter transformer, a fixed condenser and an oscillator coupler with base as shewn in the advert below.
These components do look very similar to the ones in your set so I was wondering if your set might be based on this kit.
Yours, Richard

vinrads · 18th Mar 2018, 3:48 am

I am as confused as you Chris ! but as I said the set works .

Thanks for the picture Richard, may I ask where did you find this, I have searched high and low and found nothing regarding this set, you do realise you have now set me off on another mission, that is to make a long wave coil

Mick.

PJL · 18th Mar 2018, 1:12 pm

If your circuit is correct I would say it is definitely wired incorrectly. The first IF transformer appears to be bypassed, is it open circuit?

There are some early superhet circuit diagrams here: http://www.duanesradios.info/html/ar...eterodyne.html

Circuit 1) uses a different oscillator but a loop antenna whilst circuit 4) uses a similar oscillator. Both mix by placing an oscillator secondary in series with the aerial coil.

vinrads · 18th Mar 2018, 2:48 pm

You could be right about being wired incorrectly when I first attempted to restore the set I noticed some holes at the front end ie no aerial coil fitted but all the wiring around the osc looks original , apart from the osc tuning capacitor , which didn't do anything a trial and error method got the thing tuning , tried swapping thing around as to end up with some anode volts on the first valve the rf amp , it worked but no where as good as it does now ,I have reverted back to how it was . Mick.

FERNSEH · 18th Mar 2018, 4:41 pm

PJL wrote: Circuit 1) uses a different oscillator but a loop antenna whilst circuit 4) uses a similar oscillator. Both mix by placing an oscillator secondary in series with the aerial coil.
Can you imagine the interference to nearby receivers?

Extract from the circuit diagram of the home constructed superhet receiver.

DFWB.

vinrads · 18th Mar 2018, 5:14 pm

Yes it would make a very nice transmitter, but then again who listens to am these days , I guess only people of a certain age . Like Me

PJL · 18th Mar 2018, 7:39 pm

Quote:

Originally Posted by FERNSEH

Can you imagine the interference to nearby receivers?

Nothings perfect! Not sure what the IF frequency would be but probably quite low so probably not much attenuation from the aerial tuned circuit. I know regenerative front-end receivers were frowned upon but I wonder if superhets were considered worse?

Can you draw out a bit more of the circuit including the first IF amplifier. What is the dotted line and the arrow heads?

FERNSEH · 18th Mar 2018, 8:37 pm

Hi PJL,
The extract from the 1920s superhet circuit diagram was taken from your Duanesradio link: http://www.duanesradios.info/html/ar...eterodyne.html

I do believe many early superhets employed an IF as low as 50Khz. The IF transformers in some receivers resembled audio interstage transformers.

Even as low as 30Khz!: http://www.duanesradios.info/html/ac...nsformers.html

DFWB.

vinrads · 18th Mar 2018, 9:22 pm

Quote:

Originally Posted by PJL

Can you draw out a bit more of the circuit including the first IF amplifier. What is the dotted line and the arrow heads?

Hi I find this common practice in some circuits so as not to clutter the layout to join two points with arrows and dotted lines .I find it pointless drawing the IF stages ,when the question is in the rf stage , Thank's for the reply Mick.

PJL · 19th Mar 2018, 5:38 pm

Hi Mick, did you get any further with the circuit diagram? As its most likely a kit, there is no guarantee the set has ever been wired correctly.

vinrads · 19th Mar 2018, 5:42 pm

Hi PLJ as they say work in progress , It would be nice to have the original circuit , not much hope I guess , Mick.

16th Mar 2018, 11:39 pm	#21
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Supersonic Heterodyne radio 1920's. Diodes were used as the mixer in television tuners. A 1N34 germanium diode in UHF tuners and a Mazda 6D2/EB91 double-diode in the Murphy V114 TV receiver. Don't know of any domestic radio receiver that ever employed a mixer diode. DFWB.

17th Mar 2018, 6:00 am	#22
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Supersonic Heterodyne radio 1920's. Wow ! What a great radio and worth every ounce of effort you are putting into fixing it. I particularly like that engine turning finish on the variable capacitor frames.

17th Mar 2018, 9:27 am	#23
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Supersonic Heterodyne radio 1920's. Any chance of a complete front end circuit? Or are the coils etc buried inside a proprietary unit? A redraw with signal flow left to right would be the icing on the cake.... it can be tricky driving backwards! __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

17th Mar 2018, 11:37 am	#24
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. OK some more pictures , and re drawn cct Mick. Attached Thumbnails

17th Mar 2018, 1:43 pm	#25
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. For those that are interested , a picture of the chassis in it's original cabinet .it's 38.5" x 12.5" the far right knob is a mains switch and above a led on the two volts supply above that a mains ind neon , these were to fill holes that were already there. Mick. Attached Thumbnails Last edited by vinrads; 17th Mar 2018 at 1:53 pm.

17th Mar 2018, 11:39 pm	#26
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Supersonic Heterodyne radio 1920's. Now I'm more confused. Frame tuning on the oscillator valve? I think of a frame as a large aerial coil used instead of a wire aerial. Osc tuning on 1st IFT? Are the two coils in the oscillator coupler unit the oscillator feedback HFtransformer or is one in the oscillator circuit and the other in the mixer circuit? Somewhere there has to be oscillator coupling into the RF/mixer valve for the IF to be present in its anode circuit. +2V and -2V are shown- which is actually signal ground? Probably but not necessarily common with HT-. As things stand, this appears to be a set which works in spite of how it's connected up, not because of it! __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

18th Mar 2018, 1:08 am	#27
Mr Moose Octode Join Date: Jul 2008 Location: Gloucestershire, UK. Posts: 1,043	Re: Supersonic Heterodyne radio 1920's. Hello, In 1927 Bowyer-Lowe produced a superhetrodyne constructors kit, containing three IF transformers, one filter transformer, a fixed condenser and an oscillator coupler with base as shewn in the advert below. These components do look very similar to the ones in your set so I was wondering if your set might be based on this kit. Yours, Richard Attached Thumbnails

18th Mar 2018, 3:48 am	#28
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. I am as confused as you Chris ! but as I said the set works . Thanks for the picture Richard, may I ask where did you find this, I have searched high and low and found nothing regarding this set, you do realise you have now set me off on another mission, that is to make a long wave coil Mick.

18th Mar 2018, 1:12 pm	#29
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Supersonic Heterodyne radio 1920's. If your circuit is correct I would say it is definitely wired incorrectly. The first IF transformer appears to be bypassed, is it open circuit? There are some early superhet circuit diagrams here: http://www.duanesradios.info/html/ar...eterodyne.html Circuit 1) uses a different oscillator but a loop antenna whilst circuit 4) uses a similar oscillator. Both mix by placing an oscillator secondary in series with the aerial coil. Last edited by PJL; 18th Mar 2018 at 1:22 pm.

18th Mar 2018, 2:48 pm	#30
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. You could be right about being wired incorrectly when I first attempted to restore the set I noticed some holes at the front end ie no aerial coil fitted but all the wiring around the osc looks original , apart from the osc tuning capacitor , which didn't do anything a trial and error method got the thing tuning , tried swapping thing around as to end up with some anode volts on the first valve the rf amp , it worked but no where as good as it does now ,I have reverted back to how it was . Mick.

18th Mar 2018, 4:41 pm	#31
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Supersonic Heterodyne radio 1920's. PJL wrote: Circuit 1) uses a different oscillator but a loop antenna whilst circuit 4) uses a similar oscillator. Both mix by placing an oscillator secondary in series with the aerial coil. Can you imagine the interference to nearby receivers? Extract from the circuit diagram of the home constructed superhet receiver. DFWB. Attached Thumbnails

18th Mar 2018, 5:14 pm	#32
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. Yes it would make a very nice transmitter, but then again who listens to am these days , I guess only people of a certain age . Like Me

18th Mar 2018, 8:37 pm	#34
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Supersonic Heterodyne radio 1920's. Hi PJL, The extract from the 1920s superhet circuit diagram was taken from your Duanesradio link: http://www.duanesradios.info/html/ar...eterodyne.html I do believe many early superhets employed an IF as low as 50Khz. The IF transformers in some receivers resembled audio interstage transformers. Even as low as 30Khz!: http://www.duanesradios.info/html/ac...nsformers.html DFWB. Last edited by FERNSEH; 18th Mar 2018 at 8:45 pm.

19th Mar 2018, 5:38 pm	#36
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Supersonic Heterodyne radio 1920's. Hi Mick, did you get any further with the circuit diagram? As its most likely a kit, there is no guarantee the set has ever been wired correctly.

19th Mar 2018, 5:42 pm	#37
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,761	Re: Supersonic Heterodyne radio 1920's. Hi PLJ as they say work in progress , It would be nice to have the original circuit , not much hope I guess , Mick.