10-14-2020, 11:42 AM
In other bucking transformers I've built I used a 12.6v center tapped 1A transformer, but in these for the 47-1230 I'm pretty sure I used this 2A transformer, since the set draws a little over 0.75A: https://www.digikey.com/en/products/deta...4X/5032174
and this is the switch I used: https://www.digikey.com/en/products/deta...ZQ/3751935
I did struggle with the FM in both sets but have both working well now. I don't remember all the details for the fixes, but I know in one case it was a matter of finding the right 7F8 tube. Also, based on my findings in this thread: https://antiqueradios.com/forums/viewtop...lit=philco I think the value of the 15k resistor is important in order to provide the correct voltage to the FM section.
I'm not too smart when it comes to phono problems but I would bet your problem is some sort of impedance matching issue between the cartridge and the radio.
Let me know if you want me to print a case for a bucking transformer. If so, I'll get started on it. I use PETG filament for those because it has a higher temperature tolerance than the PLA I use most of the time. I have PETG in black and gun metal grey (dark grey) so let me know which you would want. All I want for it is the price of shipping ;)
Rich
and this is the switch I used: https://www.digikey.com/en/products/deta...ZQ/3751935
I did struggle with the FM in both sets but have both working well now. I don't remember all the details for the fixes, but I know in one case it was a matter of finding the right 7F8 tube. Also, based on my findings in this thread: https://antiqueradios.com/forums/viewtop...lit=philco I think the value of the 15k resistor is important in order to provide the correct voltage to the FM section.
I'm not too smart when it comes to phono problems but I would bet your problem is some sort of impedance matching issue between the cartridge and the radio.
Let me know if you want me to print a case for a bucking transformer. If so, I'll get started on it. I use PETG filament for those because it has a higher temperature tolerance than the PLA I use most of the time. I have PETG in black and gun metal grey (dark grey) so let me know which you would want. All I want for it is the price of shipping ;)
Rich