Purpose of resistor in 37-670 - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Purpose of resistor in 37-670 (/showthread.php?tid=4909)

---

Purpose of resistor in 37-670 - AI2V - 06-23-2012

Resistor #82, 5600 ohms seems to be just a huge load to the B+ supply; twenty watts of plate power spent on this resistor. What's the purpose of it? Prevent ice from forming on the chassis?

Since this is the B supply for the audio output stage, could it be part of a kind of constant source resistance stabilizer? That's all I can think of.

Pete AI2V

---

RE: Purpose of resistor in 37-670 - morzh - 06-23-2012

I am not sure but as many tube radios do, this one has low ohm resistors connecting Neg to the chassis, creating some negative biases (wherever they might go).
Now, they rely on the consumed current to create the bis and is a bit imprecise. In this case they created the exact divider, so the voltage is less dependent on the current (still dependent though but to a lesser degree).

---

RE: Purpose of resistor in 37-670 - exray - 06-24-2012

May be to keep the B+ from soaring if the load is removed ???

---

RE: Purpose of resistor in 37-670 - AI2V - 06-24-2012

I just thought of a likely reason for the resistor- it greatly increases the current through the speaker field coil and hence it affects speaker operation. Anyone have any comments on this idea?

Since both the resistor and field coil are open and the audio output is transformer badly unbalanced, I'll be installing a PM speaker temporarily; I'm going to leave the resistor out and limit the B+ with other more practical resistors (if necessary) and see what happens.

---