----- Original Message -----
From: "Curt Nixon" <cptc...@flash.net>
To: <drakelist@zerobeat.net>
Sent: Saturday, November 17, 2012 11:22 AM
Subject: Re: [Drakelist] VTVM Probe with DMM
Hi Paul. Wouldn't it be the same thing if you set-up a
reference voltage that is -1.07V or whatever the drop is
and then pushed the relative button?
If all you are trying to do is improve upon the input Z of
the DMM, , my opinion is that I have never seen a
measurement in troubleshooting any tube set that could not
be done with a modern DMM. At 10M inputZ, it isn't going
to do much in the way of load.
Using one for an RF probe is slightly more of an issue but
with a properly built RF probe, it still is no real issue.
Perhaps I have misunderstood what and why you are trying
to acheive.
FWIW
Curt
KU8L
The idea of the 1 meg resistor at the probe tip is to
reduce the effect of lead capacitance on the measurement.
Evidently a lot of electronic voltmeters have them. In some
cases a manufacturer will specify the use of such a resistor
in making measurements. I think Collins does this in some
older manuals.
--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com
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