I need a schematic for a Monroe type D-7 model. The radio circa. 1915 t0 1925 has 2 tubes uv-199s, a variometer,variable capicitor for tuning and a reostat. One of the tube sockets has a large fuse like cartridge on it's base which I beleive to be a crystal dectector. The radio is contained in a square black wooden box with nine terminal conections around it's front edges, 3 control knobs and one 4 position rotory switch.

Juan

Hi Juan, I haven't been able to find anything on your Monroe receiver but the 199 tubes weren't available until 1923 so it's likely the set was made close to 1925. That cartidge could be a fixed crystal detector but I think it's likely to be a grid leak for the detector tube. If so it will consist of a capacitor of about 100 pf or so in parallel with a resistor of several megohms. If it really is a crystal the set might use a reflex circuit where the RF is amplifed by a tube, detected by the crystal and then the audio passed through the same tube for further amplification. I'd suspect it uses a regenerative detector and one stage of audio amplification. Hopefully someone else knows the particular set and can help with a schematic, etc. Cheers, Don Black.

: I need a schematic for a Monroe type D-7 model. The radio circa. 1915 t0 1925 has 2 tubes uv-199s, a variometer,variable capicitor for tuning and a reostat. One of the tube sockets has a large fuse like cartridge on it's base which I beleive to be a crystal dectector. The radio is contained in a square black wooden box with nine terminal conections around it's front edges, 3 control knobs and one 4 position rotory switch.

: Juan

Hi Juan, I haven't been able to find anything on your Monroe receiver but the 199 tubes weren't available until 1923 so it's likely the set was made close to 1925. That cartidge could be a fixed crystal detector but I think it's likely to be a grid leak for the detector tube. If so it will consist of a capacitor of about 100 pf or so in parallel with a resistor of several megohms. If it really is a crystal the set might use a reflex circuit where the RF is amplifed by a tube, detected by the crystal and then the audio passed through the same tube for further amplification. I'd suspect it uses a regenerative detector and one stage of audio amplification. Hopefully someone else knows the particular set and can help with a schematic, etc. Cheers, Don Black.

: I need a schematic for a Monroe type D-7 model. The radio circa. 1915 t0 1925 has 2 tubes uv-199s, a variometer,variable capicitor for tuning and a reostat. One of the tube sockets has a large fuse like cartridge on it's base which I beleive to be a crystal dectector. The radio is contained in a square black wooden box with nine terminal conections around it's front edges, 3 control knobs and one 4 position rotory switch.

: Juan

Hi Juan, I haven't been able to find anything on your Monroe receiver but the 199 tubes weren't available until 1923 so it's likely the set was made close to 1925. That cartidge could be a fixed crystal detector but I think it's likely to be a grid leak for the detector tube. If so it will consist of a capacitor of about 100 pf or so in parallel with a resistor of several megohms. If it really is a crystal the set might use a reflex circuit where the RF is amplifed by a tube, detected by the crystal and then the audio passed through the same tube for further amplification. I'd suspect it uses a regenerative detector and one stage of audio amplification. Hopefully someone else knows the particular set and can help with a schematic, etc. Cheers, Don Black.

: I need a schematic for a Monroe type D-7 model. The radio circa. 1915 t0 1925 has 2 tubes uv-199s, a variometer,variable capicitor for tuning and a reostat. One of the tube sockets has a large fuse like cartridge on it's base which I beleive to be a crystal dectector. The radio is contained in a square black wooden box with nine terminal conections around it's front edges, 3 control knobs and one 4 position rotory switch.

: Juan

Hi Juan, I haven't been able to find anything on your Monroe receiver but the 199 tubes weren't available until 1923 so it's likely the set was made close to 1925. That cartidge could be a fixed crystal detector but I think it's likely to be a grid leak for the detector tube. If so it will consist of a capacitor of about 100 pf or so in parallel with a resistor of several megohms. If it really is a crystal the set might use a reflex circuit where the RF is amplifed by a tube, detected by the crystal and then the audio passed through the same tube for further amplification. I'd suspect it uses a regenerative detector and one stage of audio amplification. Hopefully someone else knows the particular set and can help with a schematic, etc. Cheers, Don Black.

: I need a schematic for a Monroe type D-7 model. The radio circa. 1915 t0 1925 has 2 tubes uv-199s, a variometer,variable capicitor for tuning and a reostat. One of the tube sockets has a large fuse like cartridge on it's base which I beleive to be a crystal dectector. The radio is contained in a square black wooden box with nine terminal conections around it's front edges, 3 control knobs and one 4 position rotory switch.

: Juan