Ron Wagner <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Carl,
I have my original AC3 schematic in front of me now. There is a 5 ohm
resistor at the base of D4 to ground (and eclectically c2 to ground also).
The test point shorting strap is lifted and then per the manual: "To
properly set the bias voltage for 0.1 ampere idle current in the TR-3 the
voltage at this point should read 0.5 volts". 30 seconds of work, and no
worry about the accuracy, parallax, etc of the meters in Drake.
I just received the AC4R board the other day and am trying to see if I can
add this test point back without doing a "dead man's engineering" on it.
I know that no matter how I approach the issue, the AC4R will be
somewhat dangerous because the PC board has voltage around it. The
original AC3 had the TP on the top of the power supply, and all exposed
leads below the chassis. In my case, any new owner would not have to ever
use the TP if they do not want to.
73,
Ron WD8SBB
The original spec for Bias on my AC3 schematic (not loaded) was -45 to -65
V. What a range. Typical of this condition a 20% variance is not unusual.
Best and 73's Carl Hibbard
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