Emerson 415 radio low volume.

[fumplet]

This is my first radio with the resistance line cord. Ended up using a 10 uf run capacitor for the tube filaments. variac is set to 114 volts which gets me 6.3 on the filaments, so I need to install a resistor as well later.
On full volume the radio is low, very low. Schematic or instructions really dont say how long the antenna cord was. Since this wasnt a totally complete radio, I didnt get the back cover or any possable tube shields. Having a hard time even finding a picture of what a restored or unmolested chassis looks like. All caps replaced as well as every single oddball looking resistor, yes all of the resistors were bad. Havnt tested the tubes or checked voltages yet other than the 6.3 filament voltages. This chassis is really rusted it could even be a ground lug as well. speaker is repaired wire broke it rattles but works. Antenna wire is 6 feet long, which might be too short.

[Electronic M]

Most radios that didn't have a loop antenna (pretty sure the resistance cord sets predated this) expect roughly a 100' longwire antenna to work correctly.

If you have strong local stations and only care about the locals sometimes you can get away with 6'-30' or wire and or a loop antenna off a newer radio.

[fumplet]

yeah the instructions just say one can coil up the antenna wire and put it inside the set so I dont know if radio has more issues or I just need more wire which I was adding wire up to about 8 feet and then no more gain.
This weird reed speaker really does sound like junk.

[Jeffhs]

Originally Posted by fumplet

yeah the instructions just say one can coil up the antenna wire and put it inside the set so I dont know if radio has more issues or I just need more wire which I was adding wire up to about 8 feet and then no more gain.
This weird reed speaker really does sound like junk.

Some early table radios (late 1930s-'40s) had an external wire antenna and a resistance line cord. The "resistor" in the line cord was a length of wire, which caused the cord to become very warm when the radio was on; the cord had to be placed so that it did not contact anything flammable. My grandmother had one of these radios, a Sears Silvertone table set, years ago in her summer cottage; it worked well, but it overloaded like crazy on one local radio station. The station was a 50kW flamethrower, and the transmitter was just a mile or less from the cottage. I am amazed to this day the sheer strength of its signal did not keep lights on in the place, as 50kW AM stations often did years ago.

My grandmother died some time in the 1980s, and the cottage was torn down shortly thereafter. I wish she would have held on to that radio, as it would have been a collectors' item today.

BTW, I wouldn't coil up any resistance line cord as it becomes very warm, even hot (!), when the device it is connected to is operating.(This is why these cords are often referred to as "curtain burners.")This can and will cause a fire if the cord is anywhere near anything flammable, as I mentioned. The other reason these cords must not be coiled or pinched under anything is the cord can and will become very hot where it is pinched/coiled, causing the resistance wire to open in a very short time. The length of these cords is carefully calculated when the device they are used with is manufactured; lengthening or shortening the cord will alter the value of the built-in line cord resistor, possibly damaging the tubes or other parts of the device in short order.

[fumplet]

Line cord went missing from previous owners anyway but I did see what was left of it snipped off at chassis. resistance wire wound around a core. I have one other curtain burner radio, a montgomery wards airline? has a ballast resistor on the backside of it that gets smokin hot when running. Still on the hunt for low volume.. Is it the radio, me, the radio stations, or a combo of all 3 or 4 or 5 issues. Voltage checks next as the schematic lists a few to check. As far as the reed speaker Im not even sure I wanna touch it.

[old_coot88]

Does the speaker use a field coil, or permanent magnet?

[dieseljeep]

Originally Posted by old_coot88

Does the speaker use a field coil, or permanent magnet?

The thing uses a permanent magnet speaker, referred to as a magnetic speaker, such as the early RCA "tapestry" speaker. Farm radios generally used them, even Zenith. It doesn't use an output transformer.
It's best to see schematic. It has a choke in power supply.

[dieseljeep]

Originally Posted by fumplet

This is my first radio with the resistance line cord. Ended up using a 10 uf run capacitor for the tube filaments. variac is set to 114 volts which gets me 6.3 on the filaments, so I need to install a resistor as well later.
On full volume the radio is low, very low. Schematic or instructions really dont say how long the antenna cord was. Since this wasnt a totally complete radio, I didnt get the back cover or any possable tube shields. Having a hard time even finding a picture of what a restored or unmolested chassis looks like. All caps replaced as well as every single oddball looking resistor, yes all of the resistors were bad. Havnt tested the tubes or checked voltages yet other than the 6.3 filament voltages. This chassis is really rusted it could even be a ground lug as well. speaker is repaired wire broke it rattles but works. Antenna wire is 6 feet long, which might be too short.

My calculations show a 12.7 mfd for the heater dropping cap.
BTW, is that one of those "Mickey Mouse" radios by Emerson.

[dieseljeep]

Originally Posted by fumplet

yeah the instructions just say one can coil up the antenna wire and put it inside the set so I dont know if radio has more issues or I just need more wire which I was adding wire up to about 8 feet and then no more gain.
This weird reed speaker really does sound like junk.

I think those instructions are for moving the radio around! When operating, it should be unwound for the entire length of the wire.

[fumplet]

Originally Posted by old_coot88

Does the speaker use a field coil, or permanent magnet?

It has a horse shoe magnet or at least i think it is a magnet. and only one coil. I think the b+ goes through it. There is a single rod attatched to the cone sandwiched between inner and outer cone shaped washer. This rod goes to I think a flat piece of metal that sits inside this coil. This rod from the speaker is rather small about the thickness of a 32nd. I dont know if I should attempt to remove or dissassemble this speaker yet. Should just post a photo but not sure how to do that yet either.
.

[fumplet]

Originally Posted by dieseljeep

My calculations show a 12.7 mfd for the heater dropping cap.
BTW, is that one of those "Mickey Mouse" radios by Emerson.

Well it doesnt look like mickey mouse, just a dark brown bakelite radio.

[fumplet]

from what Ive learned the emerson 415 was also used in 416 and 420. I think the 420 had a tube socket hookup out the back for the battery cord but same chassis otherwise. Yes it does have a 600 ohm choke. When radio was powered on the magnet and metal around it felt like a field coil speaker. The coil measured 970 ohms. Power to radio is 114.4 volts to obtain 6.3 volts at filaments using a 10uf 370vac run capacitor for a furnace. would be nice to have a smaller capacitor but not sure thats possable. I know a 25.2 volt transformer wouuld definetly work as I have the radio shack 1.2 amp 25.2 volt unit I can use which might be safer yet no heat and no short out that caps can do. My wall voltage is 122.3, which if directly plugged into wall gets me 7.07 volts at filaments with the 10uf run cap

[dieseljeep]

Originally Posted by fumplet

from what Ive learned the emerson 415 was also used in 416 and 420. I think the 420 had a tube socket hookup out the back for the battery cord but same chassis otherwise. Yes it does have a 600 ohm choke. When radio was powered on the magnet and metal around it felt like a field coil speaker. The coil measured 970 ohms. Power to radio is 114.4 volts to obtain 6.3 volts at filaments using a 10uf 370vac run capacitor for a furnace. would be nice to have a smaller capacitor but not sure thats possable. I know a 25.2 volt transformer wouuld definetly work as I have the radio shack 1.2 amp 25.2 volt unit I can use which might be safer yet no heat and no short out that caps can do. My wall voltage is 122.3, which if directly plugged into wall gets me 7.07 volts at filaments with the 10uf run cap

I used two ceiling fan capacitors for a tiny four tube radio. They're a lot smaller than the oil type motor run caps. The fan caps are rated at 250 volts. You can fit them almost anywhere!

[fumplet]

Just picked up some caps and some are the ceiling fan caps. Hope they wont short out. Did ponder a fuse but not sure what amperage to select

[fumplet]

looking for ceiling fan run caps but wow stores dont seem to sell them locally. Thought for sure Id drum one up quickly.
Fixed miswire of the 2Meg ohm and the 1 Meg ohm resistors off the 77 and 38 tube. Im hoping these arent 2000 and 1000 ohm and Im reading it wrong again as some of these sets meg meant K. Coming off the 77 tube screen is a 2 MEG and that goes to the screen of the 38 tube. I had the 2 MEG resistor going from plate to screen of the 77 tube. The 1 MEG resistor was also miswired. Now 1 MEG goes from screen of 77 to screen of 38 . The C bias for the 38 tube is 10.8 volts, not sure if .8 is close enough to the required 10 volts specified bias for 38 tube. Still very low output although slightly better after resistor miswire. j Also going to guess the .05 cap across the line isnt responsible for the extreme loss in volume.