[Lowfer] Active Ants Redux

[Bill Ashlock]

Jay, Peter, and other E-probers,

A couple of comments:

1. The broadband E-probe (10kHz to whatever) is not necessarily the way to 
go (although it looks good on paper to see this bandwidth) if most of our 
activities are at 160 to 190kHz, and in most cases even narrower. A tuned 
front end pretty much eliminates all IM problems and requires minimal power 
- that can be fed on the lead-in. I use either a double-tuned design for the 
full band or single-tuned, for reduced coverage, in most of my probes.

2. The equipment needed to test a broadband E-probe should not force one to 
the bank. A power combiner should be replaceable with a resistor network as 
we are dealing with high impedance and very low power. Simply adding two 
signals together, resistively, should do the trick as long as the resistance 
is high enough to eliminate interaction between generators. Most of us own 
an RF signal generator, a scope, and an audio generator that could be used 
as the second generator. What's needed is the procedure to tie this all 
together, give reasonable repeatability, and better than, say, 20% 
measurement error.

Bill A

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