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650 PM Speaker Replacement
#1

Hello, another newbie with my first post. I'm restoring a Philco 650 and would like advice on replacing the speaker with a PM speaker. The original cone is trash. I think I can replace the field coil with a 1.2k 10 watt resistor since the field is not the power supply choke. The field coil measures 1175 ohms. I also would swap the audio output transformer for a 14k center tapped primary/8 or 4 ohm secondary for the PM speaker. Are there any other changes I should consider?

Rod
#2

Hi Rod, Welcome to the Phorum!!  I'll post a link to the 650 schematic to aid others in providing you advice.  You could also consider reconing the speaker.
#3

Thanks Bob, already have a quote for reconing. Just like to consider all options.
#4

So here's my dilemma; I have a Philco 650 speaker that has a badly damaged cone and an open in the output transformer (P/N 32-7078 ) primary. I looked into replacing the two components with a PM speaker and associated output transformer. Cost is around $80-$100. Another option is to rewind the transformer and re-cone the speaker. Cost, about $70. Questions arise in rewinding the transformer: 1. How do I open the transformer core? 2. What can I use to remove the paper coverings on each layer of the windings? 3. Is the primary wound on the inside, outside or intertwined with the secondary?

Does anyone have this transformer or a good replacement? I don't see going ahead with the rest of the radio till I get this resolved. (What would Marconi do?)
#5

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Ron Ramirez
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