Ron Wagner <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Jason,
I am not sure what you mean about measuring below the chassis.
- I couldn't make heads or tails of the TP-1 reading with the jumper screw
removed.
You need to measure the *voltage* from TP1 to ground (TP1 ungrounded of
course). There is actually a voltage drop over a resistor below the
chassis. That voltage is directly related to the current flowing through
the resistor. I don't have the TR3 manual handy, so I can not tell you
exactly what voltage ratio would be. But the voltage has a direct
relation to the plate meter reading.
Ohms law says current is equal to voltage divided by resistance. And what
ever the values give, that is the current. Idle is all that should be
measured this way as leaving it ungrounded will create distortion as the
bias voltage will change as the voice peaks draw more/less current.
As for being inside the MS4, well I had to remove the AC3 to change bias
any way. And you did this how often? :-) How lazy are we? :-)
See the two pictures at this link: http://www.dma.org/~wagner/ac3.htm
The TP1 is to the right and a bit up from the bias pot, between filter
caps. It used a screw from the filter cap to ground the TP. Second pic
is side view.
Hope this makes everything "as clear as mud" :-)
73,
Ron
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Visit my astronomy home page. http://www.dma.org/~wagner
Amateur Radio Station: WD8SBB - Ron and KB8NRP - Joann
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