Emerson 415 radio low volume.
 

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.

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.

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.

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.

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. :thumbsdn: It doesn't use an output transformer.
It's best to see schematic. It has a choke in power supply.

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

I think those instructions are for moving the radio around! When operating, it should be unwound for the entire length of the wire. :scratch2:

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

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!

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

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.

I got my ceiling fan caps from scrap fans. I kept the caps and the pull switches. :thmbsp:

The cap values are proper designation. Low volume on these sets are usually a lack of signal strength. Have the volume control set to max when tuning. antenna length should a minimum of 30 feet, 50 is better! Try adjusting the trimmer caps on the tuning condenser.
Is there any real strong stations in your area? 20 to 50 KW?
With the 38 output tube, it's only rated at .55 watts. Those sets really were never too loud! :sigh:

bought ceiling fan caps that have 4.5 5 and 6uf with a common gray wire. I figured I could parallel the cap itself with the values it has to get various values but if I use more than one colored wire, the radio tubes light at a much lower line voltage. Seems to only work if I parallel 2 separate physical caps together. CBB 61 is the ceiling fan cap number. NOt sure why they have 2 gray wires on these caps if they are tied to the same common end internally.
I series strung the 2 cbb 61 caps at 16uf to make 8 uf and tube voltage is 7.02 volts. Going to guess a 7 or 7.5 cap will do it.

one strong station and thats it. WHBC 1480 and its only 15kw. Im less than 5 miles from that. I usually only get 1480 and if Im lucky 1310 out of alliance ohio and thats 10 miles away WDPN. I usually lose that signal when it drops its power at night. Daytime I can maybe get it and night is good luck. Am 1060 is also dawn to dusk 15kw. I have always wanted to figure out how to get am 1310 after dusk but not sure if thats possable as IM 10 miles away from alliance ohio in east canton.
As far as loudness I only get volume the last 1/16 or slightly more of the volume knobs rotation basically 98 percent of the volume control from max. Seems somewhat odd unless I really do need the much longer wire for the antenna. Getting tired of trying to find the exact capacitor to make the tubes get 6.3 volts each. contemplating the 1n4007 diode approach. but if I were to use a diode IM not sure how much affect a capacitor would then have to drop voltage

Check the volume control curcuit and make sure of the resistance. Check to see if the control is the original! If a replacement was used, it might be not quite right! The schematic doesn't have a parts list and description. :sigh:

Ok added some more antenna wire and it didnt do much UNTIL I retweaked the trimmer caps on the tuner and that woke it up. So now it still sounds like it needs more cap filters and the dreaded speaker rattle.
Ripped off what was left of the outter speaker gasket and cut out a new one from poster board. Not quite thick enough so I will double up another gasket. speaker rattle seems gone. This set must have been really wet or dropped in a bathtub yet still works.

I love taking baths with powered radios!....So stimulating.:D

I'm big on replacing the magnetic speaker with a PM dynamic speaker. An output transformer can be obtained from a tube, battery radio that uses a 3V4 or similar output tube with a 11K or so primary impedance.
BTW, is there a 300 ohm resistor in series with the high end of the volume control? It might be part of the control!

still working on correct capacitor for line and tube voltages. Right now 7.3uf gets me 6.2 volts on tube filaments. Should I be worried about .1 of a volt Im not sure. Cannot use the fancy formula in another thread as it is supposed to use microsoft excel which requires me to go purchase microsoft 365. Swapping and combining caps is more fun anyway.
Just looked at meter and its now showing 6.24 volts. It seems to vary just like the line voltage so Im betting thats close enough.
Next is to hunt for the 300 ohm volume resistor unless its in the volume pot itself.
I have yet to figure out why bumping the tuner gets radio to play like tuner fins are losing connection to the fixed part of the tuner. Experience is telling me connection or coil bad somewhere.

With the V/C fully CW, check the cathode voltage on RF amp, pin 5, should be 2-3 volts. That will prove that the 300 resistor is part of the volume control. If not, wire in a 330 ohm resistor in series with the high end of the V/C and the cathode. Has the .1 MFD capacitor from the cathode been replaced.

No worries with 6.2V on 6.3V filaments. I use 5.9V for 10 years in one circuit I've made for audio, with ECC88, using almost every day, and tubes measures almost like new.
Even for power tubes, a little deviance is allowed, and will work perfectly.

There's always a good amount of tolerance in heater voltage. Remember series sets directly powered heaters from the wall and transformer powered sets powered them through an unregulated stepdown transformer so tubes were always exposed to the same xx% line voltage tolerance/variance as the rest of the set, and the design engineers had to plan for it.
Generally the lower the heater voltage the lower the output and the longer the life. Unless a tube or it's circuit is marginal it should run fine at the bottom end of input voltage tolerance.