Northern Electric Co.

[Dale Dieterle]

Hi All,
Did Northern Electric manufacture their own Radio Cabinets?
The small plate on the rear of my Model 623 reads “Northern Electric
fine radio furniture.

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[fedorat]

Yes All

They manufacture everything, cabinets, transformers, variable capacitors, nuts and bolts everything they needed to build a radio including the tubes, their biggest munufacturing plant was on Shearer street in Montreal.

Daniel

[Dale Dieterle]

Thanks Daniel for the info. That explains the tag.

[Eric Strasen]

Daniel,
Northern Electric’s “let’s make everything in-house” policy might explain the tube lineup in my Model 5000 Baby Champ.
This is the first post-war five-tuber I have seen which uses a 35L6, rather than a 50L6, in output, along with an 82 ohm, two watt resistor in the heater circuit to soak up the extra 15 volts.
If my 1950’s ninth-grade math serves me better now than it did then, that resistor is being highly stressed. It should be at least 2 and a half watts, and 100 ohms should be closer than 82 to achieve the required voltage drop.
I do know that the carbon resistor runs super hot.
Perhaps Northern Electric also was building six-tube sets with an RF circuit, as many U.S. makers did during the late 1940’s and early 1950’s, and found it more cost-efficient to use one tube in both types of radios.
Eric S.

[Dan Walker]

If I remember correctly I replace that resistor with one that was 5 watts just to take care of everything..

[Eric Strasen]

Thanks for the shout back, Dan.
The easy way out of this would be to swap out the 35L6 for a 50L6 and replace the resistor with a jumper wire, but that’s too simple and I have never been one to do the sensible thing.
So I ordered some 10 watt 82 and 100 ohm through-hole wirewounds from Mouser, which are due in tomorrow.
I did do a voltage check to see what is going on in the heater circuit and found that the 35Z5 and 35L6 are running at 32.5 AC. Haven’t bothered to measure the ohmage on that 2 watt carbon yet, but I’m guessing it may have drifted north some over the years.
I suspect Northern Electric got the 82-ohm value correct and my 9th grade math has failed me yet again.
Eric S.

[Eric Strasen]

No further progress on the Baby Champ yet. I want to modify the output circuitry slightly. An electronics engineer friend of mine says the audio can be improved markedly on 5 and 6-tube AC/DC sets by replacing the 150 to 250 ohm resistor running from the output tube’s cathode to ground with a 5.1 volt, 1 watt Zener diode.
The diode insures a consistent, unchanging voltage on the cathode at all volume levels, which a resistor doesn’t.
I know I have a bunch of these Zeners but I can’t find them!
Would like to make the change while the 82 ohm voltage dropping resistor is out of the way.
Oh well, I’ll just keep looking..
Eric S.

• This reply was modified 3 years, 2 months ago by Eric Strasen.

[Jean Marcotte]

Eric, you may have trouble finding you zener diodes since it took me a few days to find my Babychamp 5000. The interesting thing about it is that it has a 50L6 instead of the 35L6. You will see on the back panel a small sticker to that effect. By the way I do change all my AC/DC 5 tubes radios to 50L6 for peace of mind. An 82 ohms resistor is perfect for dropping 12 volts and I use them in empty octal sockets to isolate stages from one another. Tell us about the zener in the cathode circuit when you find them.

Jean

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[Eric Strasen]

Jean,
I gave up looking for those Zeners for the time being and ordered 25 more from Mouser.
They are so cheap that the postage was twice what the diodes cost.
I will eventually find my own large stash of Zeners, so if you could use any just drop me a note and I’ll send you some free gratis.
Note: I misquoted the voltage in my prior post. The Zeners should be 5.1 volts at 1 watt.
The following is what my friend Emailed me in September: “Most of the AA5’s and AA6’s use cathode bias in the output stage which consists of a 150 to 250 ohm resistor from cathode to ground, which yields an average bias of 5 to 6 volts. You can clip out that resistor and replace it with a 5.1 volt, 1 watt Zener diode which will make the bias completely stable at 5.1 volts irregardless of how hard the output stage is driven, or at what volume level the set is playing. Connect the banded end of the diode to the cathode and the other end to ground and you will definitely hear the difference.”
Eric S.

[Jean Marcotte]

Eric, don’t bother sending he zener. I will get them here for probably a lot less than the postage. Just give it a try and send feedback. Do you keep the usual bypass condenser ? I suppose that if you want to keep the look of the radio circuit you can encapsulate the zener in a custom made tube and paint it so that it looks like the original resistor.

Jean

[Eric Strasen]

Jean,
The bypass remains, although one may wish to melt out the wax from the old paper capacitor and restuff it with an axial mylar. My obsessive-compulsive disorder doesn’t rise to that height, or sink to that depth, since this Baby Champ is not exactly a museum piece.
As I am a scientist, however, having dissected a frog in a high school biology class, I do plan to experiment some with the Northern Electric.
Since I have been housebound for more than a week due to the frigid weather here, my mind has been wandering in dangerous paths.
As we all know, heat is a major concern in old tube radios — especially small table sets in both plastic and wood cabinets.
The 35L6 and 50L6 are pretty much identical except for heater voltage. Does the 35L6 run cooler than a 50L6?
Probably not, but I have a way to check this without incurring third degree burns.
A friend in Gillette, Wyo. is in the auto body business and has some kind of laser gadget that accurately measures heat. He is due to pay me a visit sometime this month, and I have asked him to bring his heat-measuring gun along.
He also is a crackerjack painter and no doubt could disguise the diode with bands indicating it is a 220 ohm resistor, as you suggested.
Eric S.

[Jean Marcotte]

Simple mathematics Eric. Both the 35L6 and the 50L6 draw .15 amp. Thus the 35L6 will actually run cooler. But the 35L6 plus the 82 ohms resistance will generate about the same heat as the 50L6 alone. Where is the gain? The additional heat is above the chassis and dissipates easier in the atmosphere to warm that frigid “cold air from Canada” as they say in weather reports in the States (with all the CO2 released by tar sand industry I wonder why they still make us feel responsable for cold air…). Back to the subject, the old 82 ohms resistance is more prone to failure than the tube.

Jean

[Eric Strasen]

Jean,
Has anyone considered liquid cooling?
All one would have to do is thoroughly waterproof the radio’s innards, then equip each set with some sort of mini swamp cooler. A radio’s components should last forever in this scheme, with the possible exception of electrolytics, which are cranky under the best of circumstances.
We could then return to a world of vacuum tube, hard-wired circuitry — as God intended.
Alberta seems to get most of the blame for our cold spells (“Alberta clippers”). Your own province should be viewed with affection — at least in the eastern states — as Hydro-Quebec sends us lots of electricity. Unfortunately, most Amurricans probably don’t know this.
Eric

• This reply was modified 3 years, 2 months ago by Eric Strasen.

[Jean Marcotte]

Eric,
I would not bother with the heat tube radios generate. The Babychamps are already ten years older than me and they, with a little care will outlast me by a zillion year. Now liquid cooling in your bath might be hazardous. Just take it outside in that frigid weather we are getting now and the filaments might not be powerful enough for the tubes to operate unless Hydro-Quebec gives it a boost.

Jean

[Eric Strasen]

Jean,
Perhaps I should wheel my 16-tube Midwest outside to do battle with all the cold air Alberta keeps sending our way.
Eric

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