French, Le Radio s57 help - UK Vintage Radio Repair and Restoration Discussion Forum

Rubberduck · 20th Feb 2017, 9:18 pm

I am new to this forum so please bear with me, I have a French 1957 radio, I have done best I can with it but there are a few problems I would love to sort out. Firstly the EM80 magic eye stays open most of the time unless there's a really strong signal then it moves a fraction. I feel there is an AGC problem because the weaker stations seem to disappear. In the evening they are better. Really would like the circuit but it seems impossible, any tips would be most appreciated.

westcliff · 20th Feb 2017, 9:54 pm

Hello, welcome to the forum. Do you know the make and model of your radio? I'm sure someone here will be able to help. A photo would be useful.

Gus.

Station X · 20th Feb 2017, 9:58 pm

This site is useful when it comes to French sets:-

https://www.doctsf.com/

julie_m · 20th Feb 2017, 10:31 pm

All MW / LW radios are more or less the same inside; even if they aren't fitted with exactly the same valves, they will necessarily be wired up in a similar manner. E-type valves suggest a power transformer rather than a dropper resistor, although-- especially being Continental -- it could be using an autotransformer with no isolation. There seems to have been a bit of a history of local, artisanal manufacture of radio sets in France.

It's very likely that deteriorating components in the AGC circuit could cause your magic eye problem. Over time, waxed-paper capacitors can develop a leakage resistance in parallel with themselves, and carbon composition resistors can change in value. Low values tend to drift low, whereas high values tend to drift high. I like to remember this as, they all drift away from 10 kΩ in the same direction as they already are.

There is also likely to be another capacitor that should be changed as a matter of course, on account of the scale of the carnage that can be wrought if it is faulty. (This set is French, so all bets are off ..... it could very well be a short superhet, with no audio preamp between the detector and the output valve and only the final IF transformer to give it any gain. In this case, there will be no DC blocking capacitor to worry about -- but you will need a very strong signal, and therefore a very good aerial, to get a good result from this type of set.)

How about some pictures, and maybe a list of valve code numbers?

20th Feb 2017, 9:18 pm	#1
Rubberduck Retired Dormant Member Join Date: Feb 2017 Location: Ramsgate, Kent, UK. Posts: 1	French, Le Radio s57 help I am new to this forum so please bear with me, I have a French 1957 radio, I have done best I can with it but there are a few problems I would love to sort out. Firstly the EM80 magic eye stays open most of the time unless there's a really strong signal then it moves a fraction. I feel there is an AGC problem because the weaker stations seem to disappear. In the evening they are better. Really would like the circuit but it seems impossible, any tips would be most appreciated.

20th Feb 2017, 9:54 pm	#2
westcliff Hexode Join Date: Jan 2011 Location: Essex, UK Posts: 396	Re: French, Le Radio s57 help Hello, welcome to the forum. Do you know the make and model of your radio? I'm sure someone here will be able to help. A photo would be useful. Gus.

20th Feb 2017, 9:58 pm	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: French, Le Radio s57 help This site is useful when it comes to French sets:- https://www.doctsf.com/ __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

20th Feb 2017, 10:31 pm	#4
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: French, Le Radio s57 help All MW / LW radios are more or less the same inside; even if they aren't fitted with exactly the same valves, they will necessarily be wired up in a similar manner. E-type valves suggest a power transformer rather than a dropper resistor, although-- especially being Continental -- it could be using an autotransformer with no isolation. There seems to have been a bit of a history of local, artisanal manufacture of radio sets in France. It's very likely that deteriorating components in the AGC circuit could cause your magic eye problem. Over time, waxed-paper capacitors can develop a leakage resistance in parallel with themselves, and carbon composition resistors can change in value. Low values tend to drift low, whereas high values tend to drift high. I like to remember this as, they all drift away from 10 kΩ in the same direction as they already are. There is also likely to be another capacitor that should be changed as a matter of course, on account of the scale of the carnage that can be wrought if it is faulty. (This set is French, so all bets are off ..... it could very well be a short superhet, with no audio preamp between the detector and the output valve and only the final IF transformer to give it any gain. In this case, there will be no DC blocking capacitor to worry about -- but you will need a very strong signal, and therefore a very good aerial, to get a good result from this type of set.) How about some pictures, and maybe a list of valve code numbers? __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.