daven model e radio scored
 

I just picked up a daven model e battery radio today. Radiomuseum has no info on it. Just wondering if anyone here has any info. I'm going to be in need of a schmatic. It also came with the operating manual. Posting pics below:

The 1st generation of radio technology was probably similar to the 1st generation of automobiles. Many small makers, eventually narrowed down to just several major companies. Which probably means that you may not be able to find a schematic. But odds are Daven followed a conventional design, likely a reference design created by the tube companies. Here, a "reference design" was a design created by the tube engineers to demonstrate circuits that would make the tubes work well, to help their customers like Daven get the most out of the tubes. The tube manufacturer wants happy customers. I used to do stuff like this ten years ago in Silicon Valley working for a small fabless analog chip company.

If you can't find a Daven schematic, look at other brands of radios that uses the same or similar tube line-up.

Correction, after a closer look, and looking thru the manual, it is a silvertone model E. It is listed in radiomuseum, but no actual pictures or drawings.

There is a schematic of this set at www.nostalgiaair.org
I would paste the link here but have no idea how to on this iPad..

Here it is. Click on the "eyeball" to open.

http://www.nostalgiaair.org/PagesByM...0/M0017930.pdf

These sets are very simple. Only have to check tubes, transformers, rheostat, and continuity of connections.

With two RF stages ahead of the antenna, this should be a very sensitive radio. You will probably (almost certainly) need to use an outdoor wire antenna with this set, as well as a battery eliminator or the proper batteries (the latter are very difficult to find unless you can use a 6- or 12-volt car battery).

As simple as this radio is, even with two RF stages, I wouldn't expect high performance from it. The "antenna" control on the front panel looks like an antenna trimmer adjustment. I was surprised to notice that the control marked "volume" on the panel is actually a variable capacitor, rather than a potentiometer, so it probably varied the signal strength instead of the actual audio volume. I am not an expert on 1930s radios by a long shot (nowhere near; by the time I was born, in 1956, and certainly by the time I started experimenting with electronics in the '60s, the superheterodyne principle was the industry standard), but from what I have read in posts to this forum I have learned that these 1930s battery sets were, as wa2ise noted, the first generation of radio receivers and, as such, were very simple by today's standards.

Once you get this one working at peak efficiency, however, it should serve you well. IIRC, Stroudsburg is near Philadelphia, so with a good antenna you should be able to receive most of that city's major AM stations such as KYW, et al.

I also noticed that your Silvertone model e either does not have a loudspeaker (the radio may have designed for use with headphones only) or, if it did originally have an external speaker, the latter is missing and will have to be replaced with a similar transducer (likely a horn speaker in a radio of this vintage). I don't know if a PM (permanent magnet) speaker would work with this radio; probably not, as these sets were designed to work only with their original speakers, which may well have been electrodynamic or electromagnetic. If the original speaker is of the latter design, its field coil is part of the power supply and must be present in order for the radio to work at all. Since your set is a battery radio, however, I doubt that there would be a choke coil of that sort anywhere in the power supply, although I could be very sadly mistaken as my knowledge of 1930s radios, as noted above, is extremely limited.

BTW, the shape and design of the metal tag attached to the chassis bearing the radio's model/serial number is a tipoff that your set was in fact marketed by Sears and Roebuck, although this set predates the Silvertone era; I don't think Sears used that name on their radios until the '50s, at the earliest.

The battery lineup on this is 1 6volt, 3 "B" batteries at 45 volts each, and a 22 1/2 volt. If you want to use a speaker, you use the 22 1/2 volt, if headphones, you use a 9 volt ( per manual )
What concerns me is the volume control, it looks like a pot missing it's guts ( coil )
See pic below. I'm not sure what can be used here. Any ideas?
Also this radio came with 2 extra tubes.
I have a 100' long wire outdoor antenna, so I should be fine there.

This style of radio was made in the mid to late 1920's. Earlier these tuned-radio-frequency sets had three dials, one for each tuning condensor. Then towards the end of the TRF era, manufacturers tried to simplify tuning by ganging them together on one dial. The sets didn't track perfectly thus the "antenna" control on this set which allowed tweaking the alignment of the first RF stage. People used sets like this to hear stations all over the country.

I found more pictures of the set here:

http://radioattic.com/item_more.htm?radio=0038243

It would appear that the small inner knob on the "volume" control turns the black cam on the back of the rheostat. The missing rheostat controls volume by the voltage allowed to the tube filaments. The black cam would have actuated a switch to turn the "A" power on/off. The cam appears to have a metal section on one of the indents. That section is probably connected electrically to the rest of the rheostat. A leaf spring such as one from a relay or a headphone jack or from the guts of an old telephone could be fashioned to ride on the cam to make an on/off switch. Can't tell but bet that it's a turn-turn switch that goes on/off/on/off as you keep turning in one direction.

The rheostat resistance winding missing complicates things. Finding a duplicate with concentric power switch is going to be impossible, if not worse :no: . My first thought would be to make some brackets to mount a new rheostat behind the old and put a lever arm on the new one like the old one has, and connect the lever arms together. Not impossible to do, would take a little time planning and bending up some brass strips for brackets (try a good model train shop for brass or aluminum.)

Not sure about the resistance value of the rheostat but will do some checking. Someone else may have an idea.

They used storage batteries for the A power on these sets because the tube filaments draw so much. For testing you could use a 6-volt lantern battery but it wouldn't last too long. The B supply would last longer and can be a series of 9-volt batteries snapped together + to - . A wire can be captured in between snaps at the appropriate points for intermediate B voltages like 22.5 and 45. The C supply can be made up from AA cells and will last forever. For long-term use you'd want to look into purchasing or building a power supply for the A and B voltages.

You can use any modern PM speaker with any audio output transformer between it and the radio for testing. One out of an AA5 radio would be fine.

Very nice looking radio in great condition!

I emailed the owner of that set, asked if he could take a closer pic of the switch, and if possible to get a resistance value from the switch.
I'm sure something could be adapted to work.

the gentleman replied back with a pic (attached) and said it measured 3 ohms.
I'm def. missing the winding section.

Kinda blurry, but it helps. It'd be a shot in the dark to find a winding that could be removed from another rheostat that you could adapt to that base. It looks like the cam does actuate a leaf spring contact for the switch but that part is hidden in the picture.

I'm lurking on ebay looking for a junker that has a similar control in it. Sooner or later one will show up.

http://www.videokarma.org/attachment...5&d=1295396443

Looking at the picture, I think the winding is there. It looks to be bare wire, wire made of a more resistive material than copper. The wire looks like vertical stripes on the circular part the wiper is touching. The looks of this control looks consistent with what I'd expect of such a control at 3 ohms, with nothing missing.

However, http://www.videokarma.org/attachment...9&d=1295302833 this one looks to be missing the winding.

the first photo is from another set that somebody has, the 2nd is mine...mine is missing. Anyone got something like this laying around?

Just about every 20s radio uses this type of rheostat. Now, to find just that part....

http://www.oldradioparts.com/2a21fl.txt

Playthings of the past has hundreds to choose from. Carefully read the instructions on how to send the guy an email, or it won't get through. But it looks like the control you are after will only cost you a few dollars.