12-09-2010, 11:23 AM
Well, let's see...
Both the 44 and 144 used the same filter choke, Part No. 5930. 100 H, 10 mA, 2100 ohms DC resistance.
Options?
1. Find one in a junk 44 or 144. I'm not aware of any other Philco models that used that choke. Models 29 and 45 used a similar choke, Part No. 32-7018 (70 H, 10 mA, 2300 ohms DC resistance). This would probably work OK in the 44/144 circuit.
2. Use a substitute - Hammond makes chokes; none are exact replacements, but it appears HC-154E might be in the ballpark. The inductance in henrys is a lot lower then the original (20 H), but the DC resistance is close (1666 ohms). An increase in the value of the output filter capacitor (71) should take care of any increase in ripple.
3. Have Heyboer Transformer custom wind one for you.
4. Use a 2200 ohm resistor instead, increasing the size of the output filter (71) from 6 to 22 uF. The wattage of this resistor would need to be calculated.
I have a freshly refinished 144B cathedral cabinet, and a 44 chassis to put in it. The 44 will be converted to a 144 by changing a few components and adding a shadow meter. It is also missing its filter choke, and I'm thinking about going the resistor route. Philco used resistors instead of chokes in similar circuits in some of their 1937 models; the 37-650 comes to mind as an example.
Both the 44 and 144 used the same filter choke, Part No. 5930. 100 H, 10 mA, 2100 ohms DC resistance.
Options?
1. Find one in a junk 44 or 144. I'm not aware of any other Philco models that used that choke. Models 29 and 45 used a similar choke, Part No. 32-7018 (70 H, 10 mA, 2300 ohms DC resistance). This would probably work OK in the 44/144 circuit.
2. Use a substitute - Hammond makes chokes; none are exact replacements, but it appears HC-154E might be in the ballpark. The inductance in henrys is a lot lower then the original (20 H), but the DC resistance is close (1666 ohms). An increase in the value of the output filter capacitor (71) should take care of any increase in ripple.
3. Have Heyboer Transformer custom wind one for you.
4. Use a 2200 ohm resistor instead, increasing the size of the output filter (71) from 6 to 22 uF. The wattage of this resistor would need to be calculated.
I have a freshly refinished 144B cathedral cabinet, and a 44 chassis to put in it. The 44 will be converted to a 144 by changing a few components and adding a shadow meter. It is also missing its filter choke, and I'm thinking about going the resistor route. Philco used resistors instead of chokes in similar circuits in some of their 1937 models; the 37-650 comes to mind as an example.
--
Ron Ramirez
Ferdinand IN
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