The original Tram D201 base radio was built with the tube sockets mounted to holes punched in the metal chassis. Enthusiasts like to call it the "hand-wire" D201. I prefer the term "open chassis" to distinguish it from the later version with the large circuit boards, hosting all but two of the tube sockets.
This version of the radio suffers from weak receiver volume in SSB mode. A persistent low AC hum is also a chronic complaint. The fix is easy, just use the hookup found in the later circuit-board radio. Makes it look as if Tram discovered their mistake between when the first version was shipped and when the circuit-board revision was worked out.
First step is to find V402 near the front-right corner of the chassis. Pin 6 of this tube feeds the SSB receiver audio into the disc cap C519.
Suck the solder off pin 6 of V402 and unwind the lead of C519 so we can lap solder the end of a wire to it later on. Might want to resolder pin 6 now, just so the remaining components there are firmly connected.
Now you'll need an 8-inch long piece of shielded wire. Strip the end of the center conductor on one end, and clip the braid short to the outer sleeve. Slide a piece of insulating sleeve over this end. The other end needs the center wire and shield separated.
The collector of Q500 is where the center lead of the end with the ground will go. The shield goes to the adjacent ground lug on this tie strip.
Snake the other end under the other wires to reach the socket of V402. Tinning the stripped end will prevent it from fraying while you push it under the existing wires.
Lap solder it to the end of C519 and slide the sleeve over the splice.
You'll find the sideband receive volume is now equal to AM mode, more or less. And the annoying AC hum will be reduced in a big way.
Oh, and BTW just because the speaker badge has the "Diamond" logo doesn't guarantee that the open-chassis radio is inside. A knob marked "VOX" certainly does. The circuit-board radio lacks that feature altogether. If it has a knob marked "Vox gain" and "Delay" it's the original open-chassis D201. A customer showed up with a "diamond" badged radio thinking he had bought a "hand-wire" radio. Lifting the lid revealed two large circuit boards. Boy was he disappointed when I explained that the diamond logo only shows where the radio was made. The very-first circuit-board D201s were built in New Hampshire. Only then did they move production to Mexico.
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This version of the radio suffers from weak receiver volume in SSB mode. A persistent low AC hum is also a chronic complaint. The fix is easy, just use the hookup found in the later circuit-board radio. Makes it look as if Tram discovered their mistake between when the first version was shipped and when the circuit-board revision was worked out.
First step is to find V402 near the front-right corner of the chassis. Pin 6 of this tube feeds the SSB receiver audio into the disc cap C519.
Suck the solder off pin 6 of V402 and unwind the lead of C519 so we can lap solder the end of a wire to it later on. Might want to resolder pin 6 now, just so the remaining components there are firmly connected.
Now you'll need an 8-inch long piece of shielded wire. Strip the end of the center conductor on one end, and clip the braid short to the outer sleeve. Slide a piece of insulating sleeve over this end. The other end needs the center wire and shield separated.
The collector of Q500 is where the center lead of the end with the ground will go. The shield goes to the adjacent ground lug on this tie strip.
Snake the other end under the other wires to reach the socket of V402. Tinning the stripped end will prevent it from fraying while you push it under the existing wires.
Lap solder it to the end of C519 and slide the sleeve over the splice.
You'll find the sideband receive volume is now equal to AM mode, more or less. And the annoying AC hum will be reduced in a big way.
Oh, and BTW just because the speaker badge has the "Diamond" logo doesn't guarantee that the open-chassis radio is inside. A knob marked "VOX" certainly does. The circuit-board radio lacks that feature altogether. If it has a knob marked "Vox gain" and "Delay" it's the original open-chassis D201. A customer showed up with a "diamond" badged radio thinking he had bought a "hand-wire" radio. Lifting the lid revealed two large circuit boards. Boy was he disappointed when I explained that the diamond logo only shows where the radio was made. The very-first circuit-board D201s were built in New Hampshire. Only then did they move production to Mexico.
73
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