Philco model 65 field coil replacement

5/1/2011 10:59:34 PMChris

Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.

5/1/2011 11:31:05 PMNorm Leal

Chris

You can use a wire wound resistor in place of the field and modern PM speaker. Might need to increase filter cap values to eliminate hum?

Doubt you will find a replacement choke with high enough resistance. You can series a choke, 5 or 10 henry, and resistor.

Could use an output transformer in place of the field but still be short on resistance. TV vertical output transformers should get you closer.

Norm

:Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.
:

5/2/2011 2:33:49 PMcodefox

The larger filter capacitor should be AFTER the resistor, as the smoothing that is desired would have been accomplished by the choke or field coil. Whatever value of filter capacitor BEFORE the choke or field coil shoud of course be replaced, but with nothing beyond -10 or +40% of the original value, and of course at or above the voltage. Put in a fuse while you're at it, probably 1 amp is enough.
:
Chris
:
: You can use a wire wound resistor in place of the field and modern PM speaker. Might need to increase filter cap values to eliminate hum?
:
: Doubt you will find a replacement choke with high enough resistance. You can series a choke, 5 or 10 henry, and resistor.
:
: Could use an output transformer in place of the field but still be short on resistance. TV vertical output transformers should get you closer.
:
:Norm
:
::Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.
::
:
:

5/4/2011 11:16:30 PMChris

:The larger filter capacitor should be AFTER the resistor, as the smoothing that is desired would have been accomplished by the choke or field coil. Whatever value of filter capacitor BEFORE the choke or field coil shoud of course be replaced, but with nothing beyond -10 or +40% of the original value, and of course at or above the voltage. Put in a fuse while you're at it, probably 1 amp is enough.
::
:Chris
::
:: You can use a wire wound resistor in place of the field and modern PM speaker. Might need to increase filter cap values to eliminate hum?
::
:: Doubt you will find a replacement choke with high enough resistance. You can series a choke, 5 or 10 henry, and resistor.
::
:: Could use an output transformer in place of the field but still be short on resistance. TV vertical output transformers should get you closer.
::
::Norm
::
:::Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.
:::Thankyou Gentlemen!There are 2 chokes plus the field coil on this radio.Do you mean a B plus fuse between the rectifier and resistor, and should this be a fast blow?
::
::
:
:

5/4/2011 11:16:49 PMChris

:The larger filter capacitor should be AFTER the resistor, as the smoothing that is desired would have been accomplished by the choke or field coil. Whatever value of filter capacitor BEFORE the choke or field coil shoud of course be replaced, but with nothing beyond -10 or +40% of the original value, and of course at or above the voltage. Put in a fuse while you're at it, probably 1 amp is enough.
::
:Chris
::
:: You can use a wire wound resistor in place of the field and modern PM speaker. Might need to increase filter cap values to eliminate hum?
::
:: Doubt you will find a replacement choke with high enough resistance. You can series a choke, 5 or 10 henry, and resistor.
::
:: Could use an output transformer in place of the field but still be short on resistance. TV vertical output transformers should get you closer.
::
::Norm
::
:::Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.
:::Thankyou Gentlemen!There are 2 chokes plus the field coil on this radio.Do you mean a B plus fuse between the rectifier and resistor, and should this be a fast blow?
::
::
:
:

5/6/2011 12:09:26 PMcodefox

Put the fuse on the hot leg of the incoming power cord. Does not have to be fast blow. You could also have a fuse on the B+ but this is rarely done.

::The larger filter capacitor should be AFTER the resistor, as the smoothing that is desired would have been accomplished by the choke or field coil. Whatever value of filter capacitor BEFORE the choke or field coil shoud of course be replaced, but with nothing beyond -10 or +40% of the original value, and of course at or above the voltage. Put in a fuse while you're at it, probably 1 amp is enough.
:::
::Chris
:::
::: You can use a wire wound resistor in place of the field and modern PM speaker. Might need to increase filter cap values to eliminate hum?
:::
::: Doubt you will find a replacement choke with high enough resistance. You can series a choke, 5 or 10 henry, and resistor.
:::
::: Could use an output transformer in place of the field but still be short on resistance. TV vertical output transformers should get you closer.
:::
:::Norm
:::
::::Hello everyone! I aquired a Philco model 65 ( 1929) and it is missing the field coil loudspeaker. I want to use a permanent magnet speaker at least for now.....From the schematic it says the field coil is suppose to be 3200 ohms ( I think)Is this right and is this the DC resistance?Can I replace this temporarily with a 3200 power resistor ?? If I do get a choke in the near future what size (Henries etc) would be suitable for the field coil substitute? Also can an output transformer primary be used as a choke? Thanks for any info.
::::Thankyou Gentlemen!There are 2 chokes plus the field coil on this radio.Do you mean a B plus fuse between the rectifier and resistor, and should this be a fast blow?
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