crochambeau
Active member
Yesterday I picked up a couple Technology Instruments Corp. Type 500 Wide Band Decade Amplifiers.
Before bringing up on a variac I like to give the guts a quick visual.
Which is when I saw this:
Which looks to be a pair of type 625 mercury batteries, hanging off the back wafer of the 10-100-1000 gain switch. I can't find a schematic, and outside of some EEG amplifiers which presumably used such small batteries as a reference to calibrate I've not come across this sort of thing.
Does anyone have any insight as to why there would be batteries in here? Calibration of the phase meters mentioned in the literature blurb? There's no calibrate mode selectable on front panel.
I'm attracted by the notion of having a couple 20-40-60 dBv preamps on hand, so I think my current course of action is to oust the selinium rectifier, clip the battery and see what happens. I'm just curious if there's a precedent for retaining this sort of part..
Before bringing up on a variac I like to give the guts a quick visual.
Which is when I saw this:
Which looks to be a pair of type 625 mercury batteries, hanging off the back wafer of the 10-100-1000 gain switch. I can't find a schematic, and outside of some EEG amplifiers which presumably used such small batteries as a reference to calibrate I've not come across this sort of thing.
Does anyone have any insight as to why there would be batteries in here? Calibration of the phase meters mentioned in the literature blurb? There's no calibrate mode selectable on front panel.
I'm attracted by the notion of having a couple 20-40-60 dBv preamps on hand, so I think my current course of action is to oust the selinium rectifier, clip the battery and see what happens. I'm just curious if there's a precedent for retaining this sort of part..