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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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18th Sep 2020, 3:20 pm | #1 |
Heptode
Join Date: Mar 2018
Location: Saltburn, North Yorkshire, UK.
Posts: 608
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Defiant A5 Resistor function
Just bought this Defiant A5 in great all round condition, Can anyone please tell me the function of this resistor shown in pic.
Thanks Ian |
18th Sep 2020, 3:31 pm | #2 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Defiant A5 Resistor function
Looks like a damper.
Lawrence. |
18th Sep 2020, 3:37 pm | #3 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Defiant A5 Resistor function
Yes - on LW a nicely-peaked, efficient ferrite-cored coil can have such a high Q and so narrow bandwidth that it limits the audio response (causing loss of treble). The resistor across the coil reduces the Q so broadening the bandwidth and avoiding treble-cut.
(not that there was generally much treble on LW broadcasts anyway!) |
18th Sep 2020, 4:20 pm | #4 |
Heptode
Join Date: Mar 2018
Location: Saltburn, North Yorkshire, UK.
Posts: 608
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Re: Defiant A5 Resistor function
Thanks for replies, I have managed to power it up and volume on LW is very good but on MW volume has to be turned up fully to hear stations, and then radio has to be constantly moved to improve reception on each individual station, never had one this sensitive regarding reception. The Resistor in question is 220k but is reading 6.5ohms ? Have added a few more pics just to show condition of radio.
Ian |
18th Sep 2020, 4:23 pm | #5 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,428
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Re: Defiant A5 Resistor function
The resistor is in parallel with the low resistance coil, your 6.5 ohms is the coil resistance.
__________________
Frank |
18th Sep 2020, 4:28 pm | #6 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Defiant A5 Resistor function
I always loved those Ediswan "top hat" transistors!
I see it's got a couple of the Plessey electrolytics with the red/black ends and yellow label. These are known to be a problem. |
18th Sep 2020, 4:39 pm | #7 |
Heptode
Join Date: Mar 2018
Location: Saltburn, North Yorkshire, UK.
Posts: 608
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Re: Defiant A5 Resistor function
Thanks for putting me right Frank.
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