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Monday, 30 May 2011

Am I biased?

My conundrum regarding the linear standing current may be coming to a close; with some great help from the GQRP Yahoo! group; especially G8SEQ, G3OOU and G8BEQ, it's clear that the minimum bias voltage that I have available, and hence the collector current flow is way too high.

Here is the bias circuit as published:

So I've tinkered about with different values in the circuit and now have the minimum voltage down to 0.71V and the maximum is 0.91V.

This is allowing me to set the standing current to just about any value I like; there's about a 20mA draw without the collector power connected so I've set the bias to 220mA total with both collector power circuits connected.

Now for the tests.....

1 comment:

  1. Hi could you oplease post a picture of the bias part of the circuit
    Thanks Ross Zl3dc