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Richard Clark · January 4th 09, 06:31 AM posted to rec.radio.amateur.antenna

On Sat, 3 Jan 2009 16:50:39 -0800 (PST), wrote:

The datasheet for the head gives this.

Can you quote this instead of making vague references? If you could,
then you would - this is simply more off-hand commentary....

If you're looking at the
thermistor/thermocouple mount style head,

This reveals you don't know which - each technology is very different
in operation and characteristic; much less sensitivity and power
limitation, Z shift, temperature characteristic, circuit topology, and
reference requirement to support the accuracy you suggest.

the Z looking into the head
is basically that of the load resistor, which, if held at constant

IF? Basically? You don't really know - and it appears that what
doesn't serve your defense doesn't matter.

temperature (constant = within a few degrees),

a speculative FEW degrees! You really are wandering the wilderness
here.

I doubt it changes more than a fraction of a percent.

Doubt? No metrics, except for the half-hearted guess that isn't even
close because you cannot settle on any single sensor, much less the
actual sensor!

A diode head (like the 8481,8487, etc.
for HP/Agilent meters) is also going to be pretty good.

Where the temperature characteristic of a diode is a power function?
This is growing more extravagant by each added sentence. You now have
wandered the landscape of power sensing through three technologies,
none of which you can pin down to the actual application, and without
any marked experience in the limitations of any of them.

Agillent
claims the increase in uncertainty for ALL causes from an extended
temperature (0-50) over the specified 25 +/- 5 is something like
0.9%.

And the claim is for what, specifically? The box or the head? I've
offered links to authoritative resources and specific entries, can you
recite your own or is this stuff now the domain of monkeys in lab
coats?

73's
Richard Clark, KB7QHC