Hello. I acquired an American Bosch Model 202A, and am having difficulty locating a schematic. The radio is housed in a carved "music box" type housing with a hinged lid. The nameplate at the bottom identifies it as a Model 202, the suffix A is stamped into the metal tag after the enameled 202. Although the tag is a bit scratched in that spot, I believe it says "115 volts DC" The radio has a power cord with an ordinary looking power plug on the end. The tubes are three 39's, one LA, one 52. I wonder whether this is the DC version of the model 200. How would one power such a radio? Any suggestions would be very welcome.

Lode Swinnen

Hi
If it is truly a DC set, simply using a bridge rectifier in the power line, or build one from four silicon rectifiers. Since there were numerous devices that plugged in line with radio sets as "noise supressors" and "line filters", you should be able to build something into an old metal can, or even one of those items, and make it look "correct for the period",(use a polarized plug if possible, or better, a grounded male plug end to go into the wall outlet, if possible- if you build it from just a metal can. I suggest metal because if you use a ready made bridge rectifier, you can use the can itself as a heat sink. I would figure in a little extra current capacity for the bridge, no matter which way you build it. So figuring between 3 and 5 amps with 200PIV, should be sufficient.

Before applying power, I would check to see that the filament resistors be checked to make sure they are within the correct range for the value given. Since there is no transformer, the filament voltage was probably controlled by a dropping resistor. You should have a choke, or an electrodynamic speaker field coil in the "B" circuit. I would check those resistors in the vicinity too.

I would try bringing the radio up on a variac with the bridge in circuit, start at 30 volts in the event that part of the tag that is missing had stated "not for use on 115 volts DC". (I happen to have a 32 volt Delco Chassis that someone managed to force the 32 volt plug into a 120 volt AC outlet.) If the tubes barely light (if even that much), slowly increase the voltage to 120, because you can be pretty sure that your radio is a 120 volt set. The junction resistance of the rectifiers should produce a slight voltage drop so the radio really isn't much above it's design considerations.

: Hello. I acquired an American Bosch Model 202A, and am having difficulty locating a schematic. The radio is housed in a carved "music box" type housing with a hinged lid. The nameplate at the bottom identifies it as a Model 202, the suffix A is stamped into the metal tag after the enameled 202. Although the tag is a bit scratched in that spot, I believe it says "115 volts DC" The radio has a power cord with an ordinary looking power plug on the end. The tubes are three 39's, one LA, one 52. I wonder whether this is the DC version of the model 200. How would one power such a radio? Any suggestions would be very welcome.

: Lode Swinnen

Thanks for your useful and extensive comments. That is what I will do. I'll also keep looking for the schematic, as that would explain much.

Lode Swinnen

: Hi

: If it is truly a DC set, simply using a bridge rectifier in the power line, or build one from four silicon rectifiers. Since there were numerous devices that plugged in line with radio sets as "noise supressors" and "line filters", you should be able to build something into an old metal can, or even one of those items, and make it look "correct for the period",(use a polarized plug if possible, or better, a grounded male plug end to go into the wall outlet, if possible- if you build it from just a metal can. I suggest metal because if you use a ready made bridge rectifier, you can use the can itself as a heat sink. I would figure in a little extra current capacity for the bridge, no matter which way you build it. So figuring between 3 and 5 amps with 200PIV, should be sufficient.

: Before applying power, I would check to see that the filament resistors be checked to make sure they are within the correct range for the value given. Since there is no transformer, the filament voltage was probably controlled by a dropping resistor. You should have a choke, or an electrodynamic speaker field coil in the "B" circuit. I would check those resistors in the vicinity too.

: I would try bringing the radio up on a variac with the bridge in circuit, start at 30 volts in the event that part of the tag that is missing had stated "not for use on 115 volts DC". (I happen to have a 32 volt Delco Chassis that someone managed to force the 32 volt plug into a 120 volt AC outlet.) If the tubes barely light (if even that much), slowly increase the voltage to 120, because you can be pretty sure that your radio is a 120 volt set. The junction resistance of the rectifiers should produce a slight voltage drop so the radio really isn't much above it's design considerations.

:

: : Hello. I acquired an American Bosch Model 202A, and am having difficulty locating a schematic. The radio is housed in a carved "music box" type housing with a hinged lid. The nameplate at the bottom identifies it as a Model 202, the suffix A is stamped into the metal tag after the enameled 202. Although the tag is a bit scratched in that spot, I believe it says "115 volts DC" The radio has a power cord with an ordinary looking power plug on the end. The tubes are three 39's, one LA, one 52. I wonder whether this is the DC version of the model 200. How would one power such a radio? Any suggestions would be very welcome.

: : Lode Swinnen