Atwater Kent Model 37 Almost Finished, But...

[Winky Dink]

I want to thank everyone for the help they've given me on my previous projects. Now I have a radio that's so simple that even a caveman can restore it.

I've been working on and off with this Atwater Kent Model 37 for the past year. I'm finally approaching completion. Started with this non-working set:



Now I have this:




I have a couple of issues to resolve before it goes back in the cabinet. First is the rheostat volume control. The problem is that it actually works as described below:



As you turn the knob the resistance and the volume increase until you get to the end of the resistance element, and then BAM! it jumps to infinite resistance and absolute max volume (and then your wife comes running up the stairs saying, "What in the heck was that?").



Question 1: Is there some purpose to this design? I think it would be best to have a stop so it doesn't break contact.

The rheostat spec is 0-400 ohms, and it actually reads 0-480 ohms. I get plenty of volume from a strong signal, but I've experimented with resistance up to 1K ohms, and it's still is well short of the max volume.

Question 2: Is there any reason that I shouldn't operate the set at higher rheostat resistance?

Unless advised otherwise, I'm going to put a stop at the high end of the resistance so it can't go off the volume cliff, and then add a 200 ohm resistor at the low end to boost the total resistance for more volume (volume is very soft starting at 200 ohms).

The second issue is that I receive 580 to 790 KC very well, but that's the entire range of my tuning knob. I'll ask about that later if I can't resolve it myself.

Thanks again everyone. When the radio's done I have an Atwater Kent horn speaker to work on.

If interested, this is a link to my AK37 Picasa folder:

https://picasaweb.google.com/coldrb/...eat=directlink

- Winky

[Kevin Kuehn]

It's possible they wanted that control to open up for max volume on distant station's, or alternately it may have been a simple design flaw in the controls operation. In general people were a lot more able to overlook the little technical imperfections back in the early days of radio. Obviously it took a fair amount of talent to navigate those early radio's.

I looked over the pictures in your link - a very nice job on your restoration. I can really appreciate all the time and effort that went into that set.

[Penthode]

Yes. Your restoration looks very good. Congratulations.

The antenna volume control was very common in the twenties, before AGC. 400 ohms seems a little low however. And I am suprised that a wirewound control is used as it is inductive.

Typically the rheostat antenna volume controls I have seen are between 5kohm to 20kohm carbon resistors in later twenties and early thirties sets.