28-05-2024, 05:06 PM
I downloaded this PDF, cleaned it and converted to 4 bit PNG.
It's a typical pass/fail basic USA tester like the Hickock, intended to sort new vs worn tubes. Not so great for vintage as a 1/3rd emission tube that's not faulty might be OK and irreplaceable now.
Sold in an era when getting a replacement tube was cheap and trivial
Indeed there is no clue about meter spec. Could be 50uA or more likely 1mA as the capacitor is huge.
SWB selects heater from 0.75 (hearing aid) to 117 (the rectifier that has a heater running direct off mains, 117Zsomething in Battery/Mains valve radios).
There is no separate anode and screen/g2 supplies, because each valve/tube socket connection goes to either 0V/common, heater/filament (0.75V to 117V) or HT (AC).
I think:
The rectifier is used only when the neon is in series, otherwise the valve/tube under test is the rectifier.
SW A selects one of four settings using 2 alternate HT voltages for "Normal"
SW D selects normal or leakage test with the rectifier in series.
SW 1 to SW 12 set each pin of the valve to 0V/Common, heater supply (0.75V to 117V), or the AC HT, which has four settings, but just two AC HT voltages.
Personally I'd use it for the heater supply and leakage test. Add my own new meter and separate Anode and Screen voltages each adjustable from 45V to 250V, also a 0 to -20V grid supply. This tester sets the g1 to 0V.
I'd guess one AC HT volts (positions 1, 2 & 3 of SW A) is 30V for battery valves and diodes and the other 250V is more "mains" valves. The 5.1k position 1 might be for diodes.
The 80V is AC, so 113V peak, enough for the neon to strike. I'd do a leakage test differently.
I'd not restore this as it was, as that's not very useful. I'd use it as the basis for a better tester and the SW 1 to SW 12 would need to be really 6 way, not 3 way:
1. 0V/Common
2. Heater
3. grid voltage
4. screen voltage
5. spare
6. Anode HT
The 250V transformer tap could feed two adjustable HT supplies.
The 30V tap could feed a 0 to -35V grid supply.
It's a typical pass/fail basic USA tester like the Hickock, intended to sort new vs worn tubes. Not so great for vintage as a 1/3rd emission tube that's not faulty might be OK and irreplaceable now.
Sold in an era when getting a replacement tube was cheap and trivial
Indeed there is no clue about meter spec. Could be 50uA or more likely 1mA as the capacitor is huge.
SWB selects heater from 0.75 (hearing aid) to 117 (the rectifier that has a heater running direct off mains, 117Zsomething in Battery/Mains valve radios).
There is no separate anode and screen/g2 supplies, because each valve/tube socket connection goes to either 0V/common, heater/filament (0.75V to 117V) or HT (AC).
I think:
The rectifier is used only when the neon is in series, otherwise the valve/tube under test is the rectifier.
SW A selects one of four settings using 2 alternate HT voltages for "Normal"
SW D selects normal or leakage test with the rectifier in series.
SW 1 to SW 12 set each pin of the valve to 0V/Common, heater supply (0.75V to 117V), or the AC HT, which has four settings, but just two AC HT voltages.
Personally I'd use it for the heater supply and leakage test. Add my own new meter and separate Anode and Screen voltages each adjustable from 45V to 250V, also a 0 to -20V grid supply. This tester sets the g1 to 0V.
I'd guess one AC HT volts (positions 1, 2 & 3 of SW A) is 30V for battery valves and diodes and the other 250V is more "mains" valves. The 5.1k position 1 might be for diodes.
The 80V is AC, so 113V peak, enough for the neon to strike. I'd do a leakage test differently.
I'd not restore this as it was, as that's not very useful. I'd use it as the basis for a better tester and the SW 1 to SW 12 would need to be really 6 way, not 3 way:
1. 0V/Common
2. Heater
3. grid voltage
4. screen voltage
5. spare
6. Anode HT
The 250V transformer tap could feed two adjustable HT supplies.
The 30V tap could feed a 0 to -35V grid supply.
