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Post by 2600 on Nov 22, 2021 1:00:26 GMT -5
What he said.
The emitter is the ground side of the circuit. Better to leave that emitter soldered to ground. The wire link is the hot side of the circuit and will contain DC current only. Taking the emitter lead loose opens the door to stability problems that could disrupt an accurate bias-current reading.
Using the test-point wire sidesteps that risk, since only DC current is found there. No potential RF voltages that can change the circuit's behavior. What we want is a DC current reading with no signal voltages whatever feeding into or out of the final or driver transistor. A true "zero-signal" current reading.
73
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Post by 3pinplug on Nov 22, 2021 8:05:35 GMT -5
Thanks that all makes sense, its a shame i cant post the proper 642 schematic of the area, both the radio and schematic have an extra VR to the circuit shown in the sams for the Pace 8193. Its this unidentified VR that is throwing me off track,some radios have both final and driver bias VR adjustments and as I am unsure of the reason of the extra VR i wondered if this was the same adjustment. Let me see if i can work out how to post the driver / final schematic section as you may all recognise the rogue VR’s function straight away.
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