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From: "Peter Martinez" <peter.martinez@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <000701c6781b$637b1a60$2102000a@ibm>
Date: Mon, 15 May 2006 14:12:20 -0000
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Subject: LF: Re: meter problem (2)
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Dick:

With the figures you just gave, I would suggest you to connect the voltage 
from the RF sensor circuit straight to the base of an ordinary npn 
transistor, connect the negative terminal of your 10mA meter to the 
collector of this transistor, with the positive terminal of the meter going 
to a suitable positive supply (12v?). The emitter of the transistor goes to 
ground through a 220 ohm resistor.  The voltage of the supply isn't 
critical.

To fine-tune the sensitivity you could make the 220ohm resistor adjustable. 
As Dave says, there will be a slight 'knee' in the characteristic, so the 
meter will read low if you run low power, and perhaps even not register at 
all if the power is less than 1.75 watts, but if you will not normally 
operate that low in power, you will probably never notice this.

73
Peter G3PLX