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LF: meter problem (2)

To: <[email protected]>
Subject: LF: meter problem (2)
From: "Dick" <[email protected]>
Date: Mon, 15 May 2006 14:29:47 +0200
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Some more info:

I measured the voltage available for the meter circuit at low and high power

With 60W DC input I have around 3 V and with 400W DC input this goes up to
around 9 - 10V

My meter is 10mA full scalle. With 53mV I have full scale reading , so
internal resistance around 5 Ohm.
So, with around 26.5mV I have 5mA reading.

So my meter should read around 0.5mA at 60W DC input (=3V from detector) and
about 3.5mA at 400W DC input (9V)

These are rough figures.

So, I'm looking for a circuit that can do the right "transformation" so to
Maybe it should something with an op amp.
I do have plenty of TLC271 (is offset programmable TL071) in my junkbox, or
use something else.

Hopefully someone comes along with a schematic.

Finally it doesn't have to be a circuit with very precise measuring, but a
rough indication +/- 50W would
be nice.

Dick, PA4VHF

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