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19th Jun 2021, 8:49 pm
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#1 |
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Diode
Join Date: Jun 2021
Location: Wakefield, West Yorkshire, UK.
Posts: 1
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Ekco u243/1
Hi. I have an Ekco U243/1 radio which works but it only tunes in strong signals on MW and FM. When I turn the tuning knob I get a lot of crackles through the speaker, the sound is not bad plenty of volume but a little distorted. I have cleaned the wave change contacts and the volume control as well as all the valve bases and pins; and generally cleaned both chassis and cabinet
I replaced capacitor C42 with a 0.1uF instead of a 0.01uF because I didn’t have anything else. This is the grid coupling capacitor for the output valve, but it didn’t make any difference to the overall sound quality. I haven’t replaced any shooting caps don’t have any, would this be the likely cause of the problems? The hum level through the speaker is OK. Any ideas welcome. |
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19th Jun 2021, 9:14 pm
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#2 |
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Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,286
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Re: Ekco u243/1
Excuse my ignorance, but what's a shooting capacitor?
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
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19th Jun 2021, 11:04 pm
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#3 |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,431
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Re: Ekco u243/1
Crackling when adjusting the tuning capacitor is very often due to shorts between the vanes or poor earthing on the moving vanes.
What service information are you using the output grid coupler on my diagram, manufacturer’s is C49? I don’t have the /1 version. Yes Shooting capacitor, that’s new to me. Presume you have checked voltages for the distortion problem, is it at low, high or any volume level?
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Frank |
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19th Jun 2021, 11:11 pm
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#4 | |
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Dekatron
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,754
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Re: Ekco u243/1
Quote:
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19th Jun 2021, 11:12 pm
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#5 |
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Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,710
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Re: Ekco u243/1
Shooting
Smoothing Unlikely typo, but it's all I can think of. (X with Mick.)
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-- Graham. G3ZVT |
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20th Jun 2021, 9:00 am
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#6 | |
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Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,435
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Re: Ekco u243/1
Quote:
John |
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20th Jun 2021, 10:27 am
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#7 | |
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Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,286
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Re: Ekco u243/1
Quote:
Getting back to the OP's post, C42 is not the AF coupling capacitor. The AF coupling capacitor is C49 (Manufacturer's sheet) or C52 (Trader Sheet). I suggest fitting the correct value (0.01uF) AF coupling capacitor and then checking the voltages around the PSU and output stages.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
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20th Jun 2021, 10:57 am
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#8 |
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Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,837
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Re: Ekco u243/1
This is the annoying kind of typo smartphones and tablets sometimes create when they think they know best!
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