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vfd dmm
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factory:
Another one from around 1978, the Hickok 3400, 3410, 3420 DMM, my 3400 has an unpopulated part of the PCB for the battery option.

David
Oilngas:
The 460 used 4 D cell NiCad.  According to the datasheet Eveready CH4 are 4Ah.
GigaJoe:
a popular fluke 45 has option as  a battery pack
i think it around 10-8V   , i had some idea to add type-c and battery pack with PDU 12V
Gyro:

--- Quote from: factory on April 08, 2023, 09:03:15 pm ---Another one from around 1978, the Hickok 3400, 3410, 3420 DMM, my 3400 has an unpopulated part of the PCB for the battery option.

David

--- End quote ---

That's a nice bright clean display for it's age. There's nothing sadder looking than a fading, uneven VFD on an otherwise good piece of test equipment. It seems to be a more recent phenomenon for some reason. Maybe economising on the number of filaments.
floobydust:

--- Quote from: Gyro on April 09, 2023, 10:02:51 am ---
--- Quote from: factory on April 08, 2023, 09:03:15 pm ---Another one from around 1978, the Hickok 3400, 3410, 3420 DMM, my 3400 has an unpopulated part of the PCB for the battery option.

David

--- End quote ---

That's a nice bright clean display for it's age. There's nothing sadder looking than a fading, uneven VFD on an otherwise good piece of test equipment. It seems to be a more recent phenomenon for some reason. Maybe economising on the number of filaments.

--- End quote ---

Modern VFD displays are pushed quite hard (to over 50V) and have small (anode) area and greater mux factor with more digits, they need a lot of brightness compared to these older single digit direct-drive tubes. I still have GE Y1938 in an alarm clock I built lol. That tube and the russian ones are very bright even at 15V.


--- Quote from: Oilngas on April 09, 2023, 02:35:24 am ---The 460 used 4 D cell NiCad.  According to the datasheet Eveready CH4 are 4Ah.

--- End quote ---
I imagine it has a DC-DC converter somewhere for battery operation.
The digit driver IC's SCTR0110, 24-pin DIP ceramic and maybe "H" is for Harris, no data. They would be game changers in that era.
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