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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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8th Jun 2018, 11:40 am | #1 |
Heptode
Join Date: Jan 2007
Location: Parkes, NSW Australia
Posts: 877
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Sobellette 439 distortion
I have serviced my Sobellette by replacing leaky capacitors and out of tolerance resistors. The radio works well with the volume control well advanced, but I notice that when I back the volume control off significant distortion is evident.
In this radio the volume pot varies the screen voltage of the first valve - a type 14S7. The screen voltage at maximum is 83 volts and distortion becomes apparent with the control retarded and the screen voltage at 25 volts. It gets worse as the pot is backed off further. I wonder if there is anything to be done to improve matters. Peter |
8th Jun 2018, 12:58 pm | #2 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,863
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Re: Sobellette 439 distortion
Hi Peter
I never really noticed the distortion on mine but then I wasn't expecting much anyway But it seems its a common problem https://www.vintage-radio.com/recent...bell-1950.html Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
8th Jun 2018, 1:48 pm | #3 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Sobellette 439 distortion
Lateral, Speaker? Some foul until the volume is increased.
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8th Jun 2018, 2:21 pm | #4 | |
Heptode
Join Date: Jan 2007
Location: Parkes, NSW Australia
Posts: 877
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Re: Sobellette 439 distortion
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8th Jun 2018, 2:21 pm | #5 |
Heptode
Join Date: Jan 2007
Location: Parkes, NSW Australia
Posts: 877
|
Re: Sobellette 439 distortion
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