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.

It has already been pointed out that this is not a Daven, I just wanted to add that, to complicate WA2ISE's post, Daven made their own tubes, with their own numbering system!

--Bob

I recieved a "generic" 3 ohm reostat from playthings of the past on friday. I contacted them and he said he had none with a switch on the rear. So today I gutted it. After some drilling and soldering, I have a control that will work like the original I hope :banana: Reese you were right about the switch, it does switch on the B+ power according to the diagram.
Check out the pics. the wire in the center is the feed.

Hooray! :beerchug: However, the switch controls "A" power, right?

If the rheostat has been vandalized on this set, I would be concerned with the audio transformers as well (there are 3 of them).
Are they present? are they correct? Do they have continuity?
Audio transformers, at least in my experience, have been the major issue in getting these sets working.

Heard it said that, of all things, ringer modules from old fashioned Ma Bell telephones can be substituted for these transformers. Seems that the ringer has a pair of windings, which can be repurposed to become a primary and a secondary. And possibly the bobbin holding the windings can be inserted into the old transformer laminations, if you're lucky.

Yea the transformers are there. Reese, according to the dia. the switch does switch the power to the tubes. I did'nt look real close to the dia. yet. I will check all wiring when I install the switch.

well put the rheostat in, powered it up. 4 tubes are no good. At least 1 of the transformers are working, have not checked the other 2. Somebody before I owned it had their fingers in it. I'm trying to find another diagram on it....the one I got sucks :thumbsdn:

Clean up the pins on those tubes and resolder the pins, as it's rare to find so many bad 01As in a set like that. That is, unless the previous owner hooked up B+ across the filament power by accident....

I worked on it abit tonight. Transformers appear good. Went over those 4 tubes, they are def. blown :tears: So I have to get more tubes. Schematic is very vague...anyone happen to have a better one?

Got new tubes yesterday. Found one wire missing, thats why the rear row of tubes were not lit. Hooked up a old silvertone speaker from that era and was greeted with static. Could not pull any stations in and I have it hooked up to a outside longwire. There are 2 ancient caps in it, just wondering if I should try replacing them:scratch2:

You can try replacing them. Most of those radios took 1 UF or 2 UF caps, values are not too critical. Did you check to make sure your grid leak resistor was good?

Caps are 00025 uf and 0025 uf. The grid leak resistor appears ok, not sure how to check it? What kind kind of voltages should I have on the 2 thin pins of the tubes. Again this schematic is not very detailed. The volume control does work and the brightness of the tubes increase and decrease via the volume control. I was just wondering if this is standard AM band or something else?

You can do a few checks before changing any parts. Grid leak is supposed to be 3 megohms. Anything within a few megs at this point should work for starters. Check with your ohmmeter the caps and as long as they aren't shorted the set should work somewhat.

Touch your finger or a screwdriver with your finger on it to the grid of the first audio tube: should get scratches and hum from the speaker if first and second audio tubes and second audio transformer are good.

If that works, take your antenna wire loose and touch it to the stator of the tuning condensor that goes to the detector tube. If your detector and audio stages are OK should hear a station by tuning around, maybe not too loud. If no noise, suspect the first audio transformer.

Move the antenna wire back to the next stator before the detector and test, and finally to the first one. If you lose signal somewhere look for a problem in that stage.

Problems could be open coils. Can just check each coil for continuity with your ohmmeter. Ditto each audio transformer winding. Not much to go wrong in these sets.

how's it goin reese,
I worked on it this morning, first of all the grid leak is rated 3 m-ohm. I got nothing when I used my dvm, but also have problems with that meter on anythng above 1 m-ohm.
Next went to the first audio tube, used a screwdriver, and got scratching out of the speaker. Next I checked voltages on the first and 2nd rf tubes (small dia pins) and got 91.4 v on each tube.
I then went to the first audio tube, checked the small dia pins for voltage, got 43.3 v and alot of noise out the speaker. Measured the 2nd and 3rd and got 85.2 and 82.8. When I got to the last one (detector) I got no volts. The transformer near the detector had no volts .The .002 mfd cap tested shorted, so replaced it with exact value orange dip. Then I checked the transformer and now I have voltage in and out of it. Also now checked the small dia pins on detector tube and got 124 volts. Tried the antenna lead thing and got what sounds like it's trying to tune in to stations, across all 3 stators. What I did take notice of, is there is some kind of wire wound shunt attached to one of the coils, and a clamp over it. I can see somebody was messing with it, it;s one of those things if you loosen the clamp, you can slide it to different posistions.
Also I'm running all 201a tubes in it. According to the manual, it should work satifactory with all 201a in all sockets. A special detector tube can be used in socket marked detector. Also if louder volume is needed you can use a wx112 or cx113 in the 3af socket. C power would have to be hooked up to this configuration.
What to try next?

According to the schematic there should be around 45 volts going into the detector audio transformer primary so check your wiring; should not be getting 124V at the detector plate. Check between plate terminal and B-.

Try bridging the grid leak with a high value resistor, anything from 2 meg to 5 meg should be OK. Just tack it in temporarily for now. Old grid leak may be open.

Did you check all of the RF coils for continuity with the ohmmeter?

Does the "shunt" look like a wire wound resistor with slider? Don't see anything like that on the diagram. Where is it exactly per the schematic?

what schematic do you have? can you scan a copy of it and email it?
The one I got out of riders don't list any voltages.
yea it's a wire wound mounted near the middle coil. the one lead coming from the coil hooks on it. There's one on the bottom side but that one looks like it has been untouched.
I still have to check the coils, they look good but will check anyway.

Not understanding what this..resistor, I guess? ... is doing there. Does it have continuity? Can you point out where it would be on the attached PDF from NostalgiaAir, model E?

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

Same diagram I got...how the hell do you read that???
Checked the coils, all seem ok. grid resistor read 5.3 to 7.6 m-ohms, so I put a resistor in there. Detector socket, from B- to one small pin I get 1.5 volts, to the other small pin 132 volts. I don't know which is plate or grid.
Picture is attached of the wire wound. Do I have to hook up the C power? With the current tubes in it the owners manual says not.

The top diagram from NostalgiaAir is for Silvertone model E which you say you have. On some of those early diagrams they did not show the circle of the tube envelope around the filament/grid/plate. This makes it hard for us "modern" folks to read sometimes.

Looking at the underchassis view of all of these 4-pin triodes, with the large pins at the bottom, first large pin on the left is number one. Going around the circle clockwise you have 2, 3, and finally No. 4, the other large pin. The large pins are the filament. No. 2 is the plate, and No. 3 is the grid. On No. 2 on the detector you should be getting 40-43 volts or so.

Looking at the schematic again, IF your radio is wired that way, I now see that unless C batteries are connected, the grids of the audio tubes are left floating and the radio could not work. Try this: connect three AA cells in series. You can either use a cell holder or solder short leads onto the cells to connect them. Connect as shown to the radio. You'll have 3 volts negative for the first two audio tubes, and 4.5 volts negative for the output tube.

Edit: cannot tell where in the circuit that funky resistor is connected. Can you point it out on the diagram??


http://i177.photobucket.com/albums/w...n/CBattery.jpg

The more I look at this, the more screwed up it is. Whoever had it before me really messed it up. If it was a unmolested radio when I got it, I'm sure I would have it going by now.
Somebody prior replaced the original harness, did not color code it, used yellow and reds and with a sharpie made black lines on the wires. Can not totally decifer it.
The speaker connections, 1 post comes off a transformer. The other post, had been messed with, has a red wire with black line and is suppose to go to 135 volts B side????? Plus all this is mounted on a non - conductive surface, so basicly the said speaker post goes no place but to +135. The schematic does not even show a speaker on it. The only thing I'm 100% positive of is I got the A circut correct. The only way I can get this thing going is a very detailed schematic or photo's of a unmolested one. So I guess I'll put it back in the cabinet and shelf it.

In the NostalgiaAir schematic, the speaker connections would be the two that look like headphones in the upper right corner. The speaker goes between the plate of the output tube and 135 volts. No transformer involved. Maybe they were going to use a modern PM speaker which would need an output transformer. Sending you a private message.

hey reese, maybe if you could "redraw" that schematic with some more detail and scan it I coud figure it out.

I partially redrew the schematic.

http://i177.photobucket.com/albums/w...toneModelE.jpg

Thanks reese...I'll compair it later. I already see some stuff thats different....