10-20-2011, 04:00 PM
It is easy, but it will modify your radio so that it no longer has the original volume and tone circuitry.
You will need a 1 or 2 meg. volume control, and it must have a bass compensation tap. One pulled from a 41-280 will work quite nicely. You will also need the tone control potentiometer from the same 41-280 or similar.
You will remove the old two-position tone switch and replace it with the 6 megohm tone control potentiometer. The original volume control gets replaced by the 41-280 volume control.
Connect a 68K resistor from the volume control tap to the low end of the tone control potentiometer, and a .0047 uF cap from the low end of the tone control potentiometer to ground.
Connect the center (wiper arm) terminal of the tone control potentiometer to ground.
Now connect a .0068 uF cap from the high side of the tone control potentiometer to the plate of the "det. amplifier" tube, a 44.
You can see the actual circuitry by looking at a 41-280 schematic, although the values of the added resistor and two caps are different from those shown in the 41-280 schematic.
This hot-rod circuit will make your 71 sound like a big console radio - but, as I said, it isn't original!
I did this to my "Super" 71 because it was a rust bucket to begin with, a chassis that some people might have just tossed out.
http://www.philcoradio.com/notebook/super71.htm
I would not do this to a good chassis, but that's just the way I am. I prefer to keep the good stuff original; but I am not opposed to experimenting on junk sets.
You will need a 1 or 2 meg. volume control, and it must have a bass compensation tap. One pulled from a 41-280 will work quite nicely. You will also need the tone control potentiometer from the same 41-280 or similar.
You will remove the old two-position tone switch and replace it with the 6 megohm tone control potentiometer. The original volume control gets replaced by the 41-280 volume control.
Connect a 68K resistor from the volume control tap to the low end of the tone control potentiometer, and a .0047 uF cap from the low end of the tone control potentiometer to ground.
Connect the center (wiper arm) terminal of the tone control potentiometer to ground.
Now connect a .0068 uF cap from the high side of the tone control potentiometer to the plate of the "det. amplifier" tube, a 44.
You can see the actual circuitry by looking at a 41-280 schematic, although the values of the added resistor and two caps are different from those shown in the 41-280 schematic.
This hot-rod circuit will make your 71 sound like a big console radio - but, as I said, it isn't original!
I did this to my "Super" 71 because it was a rust bucket to begin with, a chassis that some people might have just tossed out.
http://www.philcoradio.com/notebook/super71.htm
I would not do this to a good chassis, but that's just the way I am. I prefer to keep the good stuff original; but I am not opposed to experimenting on junk sets.
--
Ron Ramirez
Ferdinand IN
