12-28-2013, 07:19 PM
I am about to plug it in to see the transformer voltages.
Before I do it, I eventually took a look at the speaker. I might've written it has been repaired and reconed. Now the field coil which, I think, should be around 3kOhm, is serialized with a resistor and is total of 1.9kOhm, of which the resistor accounts for 1.2kOhm which leaves 700 Ohm for the coil. I do not know whether or not it is sufficient for full power and good quality, the future will tell.
The voice coil is 6.2 Ohm (as I remember the original Philco 20-70-90 coils were about 0.1 - 0.2 Ohm) and the transformer has been replaced. I do not have an audio generator so at this point I cannot reliably measure the turns ratio. Although I think I could use the variac to do this, it's just I do not like variac for this purpose. I need to know the ratio to know whether the transformer was chosen with proper regards to the new voice coil impedance.
In any case it will likely work well enough to get the radio going.
Before I do it, I eventually took a look at the speaker. I might've written it has been repaired and reconed. Now the field coil which, I think, should be around 3kOhm, is serialized with a resistor and is total of 1.9kOhm, of which the resistor accounts for 1.2kOhm which leaves 700 Ohm for the coil. I do not know whether or not it is sufficient for full power and good quality, the future will tell.
The voice coil is 6.2 Ohm (as I remember the original Philco 20-70-90 coils were about 0.1 - 0.2 Ohm) and the transformer has been replaced. I do not have an audio generator so at this point I cannot reliably measure the turns ratio. Although I think I could use the variac to do this, it's just I do not like variac for this purpose. I need to know the ratio to know whether the transformer was chosen with proper regards to the new voice coil impedance.
In any case it will likely work well enough to get the radio going.
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