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 HMV 61-51 speaker transformer
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 Return to top of page · Post #: 1 · Written at 3:33:15 PM on 13 December 2025.
John116's Gravatar
 John116
 Location: Ryde, NSW
 Member since 29 October 2008
 Member #: 370
 Postcount: 111

Hi - looking for a speaker transformer for an HMV 61-51 mantel radio. I assume a 7k/4 ohm generic transformer would be Ok as well? Hard to find though....

Am in Sydney.

Thanks,
John
 
 Return to top of page · Post #: 2 · Written at 10:38:24 PM on 13 December 2025.
Marcc's avatar
 Marcc
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5671

Might have one in a HMV wreck, albeit I and many others have used "Line Transformers" Which are readily available. I find audio transformer fails in HMV's to not be that common. Tube data for 6M5 says 7K.

Make sure the screen resistor 10K is ok they changed it from parallel 22K and some have a tendency to burn.
 
 Return to top of page · Post #: 3 · Written at 8:32:20 AM on 14 December 2025.
Ian Robertson's Gravatar
 Ian Robertson
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2680

Part number MM1900 at Jaycar will do the job.

I think that radio has negative feedback, so, if it screams at you, reverse the primary OR the secondary connections.

The output taps allow you to use different impedance speakers. Start with the lowest one and see if the next one up improves the power output.
 
 Return to top of page · Post #: 4 · Written at 7:00:57 AM on 15 December 2025.
John116's Gravatar
 John116
 Location: Ryde, NSW
 Member since 29 October 2008
 Member #: 370
 Postcount: 111

Thanks all, I'll try the Jaycar option. The primary on the original transformer is open circuit.
 
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