[Lowfer] Active Ants Redux

[Jay Rusgrove]

Bill

In my case I use for 60 kHz, 75 kHz, the 136 kHz band, 160-190 kHz, NDB,
broadcast band, hifer band, WWV and a host of other frequencies. For me this is
the main attraction of the AMRAD antenna.

The signal generators can be as simple as crystal or LC oscillators with decent
internal low pass filters in a shielded double sided pc board box. At these
frequencies  step attenuators can be built with slide switches as long as
shielded partitions are used between sections - easy to fabricate with doublepc
board material. The combiner can be wound on a single surplus ferrite core -
again in a  shielded pc board box. A collection of this type of stuff can be
seen in the ARRL Handbook circa 1980. This shouldn't put anyone in the poor
house.

In addition to e probe testing this same equipment could be used to evaluate
receivers, up converters and other preamplifiers and modifications done to same.

I think the testing procedure should follow closely the standard methods used
for amplifiers/receivers that has been in place for years and widely known
throughout the rf industry. Don't think there will be one "figure of merit" that
will cover it all. Guess that's why we have 1 dB compression, 3rd order
intercept, 2nd order intercept etc etc.

Jay

Bill Ashlock wrote:

> 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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