On Wed, Sep 18, 2019 at 10:18 PM, cmjones01 wrote:
Some thoughts without studying the schematics too long.
I choose a similar remedy for a P6302. Soldered R18 to "A" and decreased the value. Wired side "E" of the Hall sensor to "K" (gnd) via 18k. Both action pulled the + of the opamp more negative.
A slight reduction in gain is only possible (I think) when there is not enough amplification by the DC amplifier (the feedback to zero out the DC flux component is not satisfying). Maybe your action put a heavier load on the Hall output. In my opinion the effect would be that the low frequency gain is now slightly smaller than the high frequency gain. AM503 Gain adjust R344 is common to both, so can't help. I'm not sure whether I ever carefully checked the frequency response of the P6302.
With that probe the scope trace is also very "jumpy". The probe is nearly useless in the most sensitive settings of the AM503. From all old messages at the time (especially by Steve Ditter) I concluded that the Hall sensor was desintegrating.