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Old 30th Jul 2019, 10:32 pm   #14
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Tektronix 7A26 problems

Quote:
Originally Posted by dave cox View Post
My analysis is the OC outputs (9,6,8,5) are either :-
(1) delivering too much current, pulling the voltage low. Controlled by R1320 & R1323 (681), R1339 & R1338 (36)
(2) their load is too high a resistance, R1347 (280R), R1343 & R1341 (56), R1403 & R1401 (60R4)

Gilbert cell 155-0078-00

dc
It should really be named a Jones Cell, Jones invented it in the early 1960's and did not patent his work. The Nagra tape recorder company also used the 4 quadrant multiplier as a phase detector in their machines to crystal lock the tape speed, prior to the Gilbert patent too. It makes for a great scope input amplifier as a monolithic IC (temp drifts cancel) and it is extremely easy to invert a channel by altering a reference voltage on one of its ports.
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