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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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21st Feb 2017, 10:30 pm | #1 |
Tetrode
Join Date: Mar 2010
Location: Monroe, Georgia, USA. (from Coventry, UK).
Posts: 77
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Sky Casket output transformer resistance
Last year, while back home in the UK for a holiday, I treated myself to an Ever Ready Sky Casket. I have just put it on the bench, and have found that all four valves are dud. Three have open filaments, and the fourth has very low emissions. Anyway, before looking for a set of valves I thought it would be a good idea to verify that the output transformer is OK. I disconnected one lead from primary and secondary, and checked DC resistances. Primary is around 550 ohms, and secondary is 0.7. Could anyone tell me if these are reasonable values?
Thanks in advance for the help. Regards, Colin |
21st Feb 2017, 10:34 pm | #2 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,923
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Re: Sky Casket output transformer resistance
They sound ok to me.
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21st Feb 2017, 10:34 pm | #3 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: Sky Casket output transformer resistance
The DC resistance of the output transformer sounds correct.
Cheers Mike T Crossed with Hamish
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21st Feb 2017, 10:40 pm | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,527
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Re: Sky Casket output transformer resistance
Sounds reasonable. Another check would be to reconnect speaker to secondary, connect a 1k resistor across the primary then dab a 9V battery across the primary. This should give some good crackling noises from the speaker.
The 1k will limit inductive kick back voltages to a safe level for the TX insulation.
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22nd Feb 2017, 12:39 am | #5 |
Tetrode
Join Date: Mar 2010
Location: Monroe, Georgia, USA. (from Coventry, UK).
Posts: 77
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Re: Sky Casket output transformer resistance
Thanks you all for the prompt replies. I now feel confident about searching for a set of valves.
Regards, Colin |