08-09-2026, 11:11 PM
Sweet!!! You got the speaker grille cloth spot on! The sides look great. The grille on these is usually a total mess and you resurrected that also.
Do you have pics of the chassis also. If in a previous post, please send a link.
I have a 20 also (actually, I have 2). These are interesting sets as they don't work like later model superhets. Volume is controlled by shunting the antenna coil and biasing the RF amps. A properly designed TRF can give very good fidelity.
The audio interstage transformers have a way of the primary opening up. There are techniques for "bridging" the primary if this happens. If the primary is good, there is a technique for capacitively coupling so as to keep DC current off the primary. This may prevent a burnout and is supposed to greatly increase the fidelity. I have done so and believe that it does help. The link is here:
https://philcoradio.com/library/index.ph...nsformers/
One of these days I am going to put a Radio / Aux switch into it.
Depending on the age of the set, there are 2 different versions of the speaker. For the earlier version, the "spider" (the part that holds the voice coil centered in the magnetic field) is like an inverted metal cap and is very inflexible. The later version which looks like one of those 45RPM record center hole adaptors (OK, you may have to be 70+ years old to remember those) is more compliant and provides better fidelity, especially bass response.
Do you have pics of the chassis also. If in a previous post, please send a link.
I have a 20 also (actually, I have 2). These are interesting sets as they don't work like later model superhets. Volume is controlled by shunting the antenna coil and biasing the RF amps. A properly designed TRF can give very good fidelity.
The audio interstage transformers have a way of the primary opening up. There are techniques for "bridging" the primary if this happens. If the primary is good, there is a technique for capacitively coupling so as to keep DC current off the primary. This may prevent a burnout and is supposed to greatly increase the fidelity. I have done so and believe that it does help. The link is here:
https://philcoradio.com/library/index.ph...nsformers/
One of these days I am going to put a Radio / Aux switch into it.
Depending on the age of the set, there are 2 different versions of the speaker. For the earlier version, the "spider" (the part that holds the voice coil centered in the magnetic field) is like an inverted metal cap and is very inflexible. The later version which looks like one of those 45RPM record center hole adaptors (OK, you may have to be 70+ years old to remember those) is more compliant and provides better fidelity, especially bass response.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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