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 Centre tapped 6.3 volt heater winding.
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 Return to top of page · Post #: 1 · Written at 3:19:37 PM on 19 April 2024.
Bowler's Gravatar
 Bowler
 Location: Bongaree, QLD
 Member since 26 October 2018
 Member #: 2308
 Postcount: 95

Good Afternoon all, can somebody explain the necessity to provide a centre tapped heater winding in a valve radio. bowler
 
 Return to top of page · Post #: 2 · Written at 7:52:55 PM on 19 April 2024.
Marcc's avatar
 Marcc
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5474

The general idea relates to hum cancelation it is most common on sets where it has a filament rather than a heater and its an AC filament.

It is however, not unusual on some heater tubes; However, it should be noted that the heater tubes will only be grounded via that centre tap.

A fact of life is that you can get hum modulation at the Mixer and sometimes from heater to cathode leakage.
 
 Return to top of page · Post #: 3 · Written at 10:31:39 AM on 22 April 2024.
Bowler's Gravatar
 Bowler
 Location: Bongaree, QLD
 Member since 26 October 2018
 Member #: 2308
 Postcount: 95

Thanks Marcc, your reply was most informative . bowler
 
 Return to top of page · Post #: 4 · Written at 10:06:24 AM on 4 May 2024.
6A8G's Gravatar
 6A8G
 Location: Wellington, NZ
 Member since 24 July 2009
 Member #: 517
 Postcount: 63

& don't forget if your transformer doesn't have a centre tap you can manufacture one by installing a 100-ohm resisistor from each side of the winding to ground. A rating of one watt is sufficient.
-JR.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
6A8G.

 
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