My latest auction win

[GK]

1x HP 1600A Logic State Analyser with the full complement of probes. Not quite as cool or historically significant as the 5000A LSA, but neat nonetheless. Will be just perfect for probing my discrete digital computer project.
1x Fluke 8502A 6.5 digit multimeter. Except for some exterior dust is in mint condition and appears to be fully optioned.
1x BK Precision 530 semiconductor tester (not that exciting)
1x HP 6111A precision power supply. Works fine but I'll give it a re-cap before finding a permanent place for it on the bench.

[TheBay]

Nice score 

[EEVblog]

I used to have a Gould CRT logic analyser. Those were the days.

[GK]

16 word memory depth!!!

The row of 16 toggle switches are used to set the triggering word and the thumbwheel switches allow you to select the number of clock pulses ( 0 to 65535) to elapse before data is acquired.

[Gyro]

I love the 1600A, we used to have one with the serial data stream adapter underneath it. If I remember correctly there's a knob that blanks off the screen from the right to make reading smaller data widths easier, when you turned it, it felt just like you were closing a curtain  Analogue of course.

[GK]

Yes that's right; of the pair of knobs on the right hand side of the screen, it's the one farthest right, entitled "Column blanking". There are two banks (Memory A and Memory B) of sixteen 16-bit words displayable. The column blanking control works on both banks simultaneously. Also of note the persistence of the CRTs phosphor is really sloow. When I first twiddled the column blanking knob I initially thought the function was dodgy; it takes several seconds for the curtained columns to fully disappear.

Some pictures inside the Fluke. Turns out it isn't fully optioned as two card slots are vacant; haven't looked up what functions they are yet though. The DC reading doesn't agree with my Agilent handheld and it intermittently goes unstable, so some work will be required here. However besides the inaccurate readings the unit appears to be completely functional.
   
The RMS-to-DC converter is mostly discrete:

[dr.diesel]

Nice score on some vintage iron.  What reference is in that 8502A?

[GK]

For U1 the parts list just states "U1: REF. AMP SET (U1, R9, R14, R15, R16), Fluke stock #415034, MFG Supply code 89536".
So I guess just a propriety part supplied with a set of matched/selected compensatory resistors.

[dom0]

LTFLU-1 or it's almost identical predecessor whose name I forgot just googled (SZA263)?

[GK]

Is there a datasheet for this thing floating around anywhere? I've followed a dozen+ links so far to no avail.

[dom0]

There are no specifications regarding these two parts publicly available, at least not that I'm aware of it.

[GK]

Looks very strongly like this super reference might be something as rudimentary as a zener diode compensated by the opposing temperature coefficient of the Vbe potential of the paired transistor effectively used as a negative-feedback loop/regulator error amplifier.