Atwater Kent Model 55C

8/18/2008 12:05:43 PMLou

All:

I have an Atwater kent model 55C. In looking at the schematic, it looks like the unit uses a speaker with a field coil. The coil looks like it is powered off of a tap on the negative side of the power supply.

Can I run a high Z PM speaker (2000 ohm) on this radio?

What happens to the PS if the field loading is not there ( i.e. PM speaker has no field).?

Thanks
Lou

8/18/2008 12:46:05 PMDoug Criner

Lou: With a PM speaker, and no field coil, the radio won't work. There will be no B+ voltage.

You can jury rig a 2500 power resistor in place of the field coil, but there will likely be extra hum. Or, you can replace the field coil with a suitable choke.

The AK F-4 speaker was tailor made for the 55. That would be you best bet. If you buy one, make sure it comes with the speaker plug, which is non-standard.
Doug

:All:
:
:I have an Atwater kent model 55C. In looking at the schematic, it looks like the unit uses a speaker with a field coil. The coil looks like it is powered off of a tap on the negative side of the power supply.
:
:Can I run a high Z PM speaker (2000 ohm) on this radio?
:
:What happens to the PS if the field loading is not there ( i.e. PM speaker has no field).?
:
:Thanks
:Lou

8/18/2008 5:17:43 PMLou

:Lou: With a PM speaker, and no field coil, the radio won't work. There will be no B+ voltage.
:
:You can jury rig a 2500 power resistor in place of the field coil, but there will likely be extra hum. Or, you can replace the field coil with a suitable choke.
:
:The AK F-4 speaker was tailor made for the 55. That would be you best bet. If you buy one, make sure it comes with the speaker plug, which is non-standard.
:Doug
:
::All:
::
::I have an Atwater kent model 55C. In looking at the schematic, it looks like the unit uses a speaker with a field coil. The coil looks like it is powered off of a tap on the negative side of the power supply.
::
::Can I run a high Z PM speaker (2000 ohm) on this radio?
::
::What happens to the PS if the field loading is not there ( i.e. PM speaker has no field).?
::
::Thanks
::Lou

8/18/2008 5:18:43 PMLou

Doug:

This is a 55C.

According to the schematic, the B= is continuous in the power supply. The field coil is in parallel with the B=, not in seties with it.

Lou

::Lou: With a PM speaker, and no field coil, the radio won't work. There will be no B+ voltage.
::
::You can jury rig a 2500 power resistor in place of the field coil, but there will likely be extra hum. Or, you can replace the field coil with a suitable choke.
::
::The AK F-4 speaker was tailor made for the 55. That would be you best bet. If you buy one, make sure it comes with the speaker plug, which is non-standard.
::Doug
::
:::All:
:::
:::I have an Atwater kent model 55C. In looking at the schematic, it looks like the unit uses a speaker with a field coil. The coil looks like it is powered off of a tap on the negative side of the power supply.
:::
:::Can I run a high Z PM speaker (2000 ohm) on this radio?
:::
:::What happens to the PS if the field loading is not there ( i.e. PM speaker has no field).?
:::
:::Thanks
:::Lou

8/18/2008 6:47:45 PMDoug Criner

Lou - this is the schematic that I'm looking at (modern, drawn by Leigh):
http://www.atwaterkent.info/TechData/Drawings/Images/AK14902sch.pdf

I now see what you're saying. Sorry.

However, without the field coil, the B+ will be high, and maybe more hum. Best to replace it with a 1100-ohm power resistor.

:Doug:
:
:This is a 55C.
:
:According to the schematic, the B= is continuous in the power supply. The field coil is in parallel with the B=, not in seties with it.
:
:Lou
:
:::Lou: With a PM speaker, and no field coil, the radio won't work. There will be no B+ voltage.
:::
:::You can jury rig a 2500 power resistor in place of the field coil, but there will likely be extra hum. Or, you can replace the field coil with a suitable choke.
:::
:::The AK F-4 speaker was tailor made for the 55. That would be you best bet. If you buy one, make sure it comes with the speaker plug, which is non-standard.
:::Doug
:::
::::All:
::::
::::I have an Atwater kent model 55C. In looking at the schematic, it looks like the unit uses a speaker with a field coil. The coil looks like it is powered off of a tap on the negative side of the power supply.
::::
::::Can I run a high Z PM speaker (2000 ohm) on this radio?
::::
::::What happens to the PS if the field loading is not there ( i.e. PM speaker has no field).?
::::
::::Thanks
::::Lou