[Miken]

Is the 37-116 and the 38-116 the same chassis? Thanks

[Radioroslyn]

No they are different. Sub chassis and output stage are two things that come to mind. Field coil in the speaker is different and isn't interchangeable between the two chassis.

[rfeenstra]

No, not exactly. The RF chassis on the 38 is simplified from the 37. It is easier to rebuild. The tube compliment is different. Different mixer tube, 1st audio, audio driver and outputs, and the rectifier.. The 37 uses 6B4 outputs. These are filament cathode outputs necessitating a hum balance pot. The 38 uses 6L6's. I just finished a 37-116 (did one a year or more ago as well), and finished a 38-116 a couple of months ago. Both great radios! As well as what Terry just mentioned about the speaker.

[morzh]

All is correct except the speaker is the same between the two, and both field coils are 330 ohms.
The 690 sets have same type speakers but indeed with different coils, much higher resistance used as load and not as filter.

[rfeenstra]

When Terry said that I measured the field coils of my 38 and 37 sitting here. The 37 measured 350, the 38 330. The schematic for the 38 says 350 ohms, and the schematic for the 37 says 400 ohms. I know that , for a while, I had the speaker for the 37 hooked up to the 38. The field coils for the 38 and 37 are in the B- supply, rather than in the B+ supply, hence the lower resistance.

[morzh]

I think it says 360 on 37116 and 350 on 38116. (Riders readability in these is somewhat meciocre).
I think it is 36-3647 cone and voice assy in both radios.
So, for all intents and purposes, it is the same part.

[rfeenstra]

Yes, the Riders parts list for the 37-116 code 122 and 38-116 code 125 list the voice coil and field coil as the same part number, yet they list the resistance on the schematic as 400 ohms and 350 ohms respectively (I have high res scans that clearly show the part numbers.) I suppose the discrepancy is of little consequence considering it's a small percentage. Just wonder why the discrepancy. Probably different people with different sources drawing up the schematics. Regardless, the 37 and 38-116 speakers do seem to be interchangeable. Thanks morzh!

Probably more info than you wanted, Miken!!!

[morzh]

This is Riders 37-116 sch, I cut out the field coil part.

   


Doesn't look like 400 to me.

The one that says 400 is the choke, the FC, part #122, says 360.


Now to compare, 38-116.
Part #132

   





But the best part is, bith radios list the FC as PN 36-3788. Which means, they use the same field coil.
Coupled with the same cone/voice assy, it makes it the same exact speaker.

[Radioroslyn]

Apologies gents. I had in the back of my mind that the coils were different resistances. As Mike sez the resistances are negligible. The plate load impedance of triode vs penode output tube tend to differ. Triodes usually are lower.

[Miken]

Thanks to all, never too much information.

[rfeenstra]

Oops!  I'm cross eyed.  I was looking at the choke, which is 400!  Mea culpa!

[morzh]

I just remembered that when years ago (like 6 years) Tex was looking for 38-116 speaker, he was told 37-116 was the same....