[Arran]

Ron,

You had replied back to me in the Wanted Ads thread about my missing 38-5 speaker:

RE: ATTN Ron Ramirez: WTB Philco 38-5 Speaker
Okay...I had forgotten to whom I had sold that radio!

I've since replaced it with another 38-5B, and wouldn't you know it, this one has a speaker, but it is not an original Philco speaker.

Anyway...

The original speaker used was a K-39. 660 ohm field, 1.25 ohm voice coil. Primary impedance of the push-pull output transformer: 14,000 ohms.

Now you need to replace it.

You need a speaker with a field coil in the range of 660 ohms (650 is OK). You can always mount a new "universal" push-pull output transformer onto a replacement speaker.

There are a few other Philco models that used speakers with 660 ohm fields, but not very many. Here's the list:

K-23: Used in Model 19 Code 128, and Model 144B. (Uses a single ended audio output transformer that will have to be replaced with a push-pull unit.)
K-34: Model 37-640B. (Original push-pull transformer will work in the 38-5.)

Your other option is to install a PM speaker and replace the field coil with a 660 ohm, 25 to 50 watt resistor. 25 is actually large enough but 50 gives you a greater margin of safety.

I think I would have a hard time finding the K-23 or K-34 speakers. I looked on eBay and found a couple but they are in full sets. I think my best option would be to purchase a modern permanent magnet speaker. However, I'm not sure how I would actually hook it up. According to the schematic it looks like there would be 3 wires going to the K-39 speaker but there are 4 wires that connect to the speaker plug. A modern PM speaker has 2 connection lugs. How would I actually connect the wires from the plug to the PM speaker? Where would I connect the 660 ohm resistor?

Thanks,
Geoff

I would use a filter choke rather then a resistor, unless it's just temporary, there is even a solid state circuit that may work as a choke substitute, a used one will do, so will a 9 inch electrodynamic of another brand, even though the bolt pattern is a little different. But don't give up looking for a speaker though, you best bet to find one is to hit the swap meets and look for junkers.
Regards
Arran