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Unfortunately, I'm not a nanosaver expert, so I can't answer.
With that said, if your calibration constants have become corrupt, that
might produce some strange errors. Make sure cal is enabled on the nano.

On Monday, January 4, 2021, 11:36:22 a.m. EST, John, G4DRS via
groups.io <g4drs@...> wrote:

OK,
Thanks, but why do I get that error message? I have used this setup in the
past without seeing the errors.


John
G4DRS

On 1/3/21 7:06 AM, Brian wrote:

I understand the value and significance of tuning an antenna to be

resonant. I think I understand the previous post about, quarter and half
wavelengths of feedline, resistance and reactance and the effects of the
feedline. So my question is from a practical application don't we want to
measure the resonance of the antenna and feedline and have everything
"tuned" as a system? Antennas don't operate in isolation, they operate in
conjunction with the feedline and transmitter, so I want a system that is
as efficient as possible. Maybe we want to measure each part of the system
and tune it for the band/bands we are operating on. IF I am correct, then
what is the best or most practical way to measure the system and make the
adjustments?

What matters, in most cases, for a single antenna is the radiated field
strength in the far field, in the direction you want to radiate. For
receiving, it's reciprocal, so tuning for max smoke on Tx works for Rx
too. (with the proviso that we're not talking phased arrays or nulling
interference)


Operating at the antenna's resonant frequency (defined as where the
imaginary part of the feedpoint impedance is zero) , per se, doesn't
have a huge effect on the radiation efficiency. (highly reactive
antennas with tuning components, like compact loops, are tricky here)


Transmitters only have a "nominal" output impedance - they may well put
out more power if terminated into an impedance other than the nominal.
And some transmitters have adjustable output impedance (i.e. vacuum tube
amplifier with an adjustable plate network).

So, best approach - characterize all the components in the chain - Do a
load pull on the transmitter to get its output characteristics. Measure
the feed lines. Measure the antenna. Take all those and put them into a
mathematical model and optimize for radiated field.

Until recently, doing all these measurements would be a pain, so nobody
does this, at least not in the amateur radio world. It's essential in
the phased array world, so people who are doing phased arrays
(particularly adjustable ones) are always looking at the mutual Z matrix
and the radiation patterns.

What amateurs do is usually some form of "minimize feed line losses",
which is a combination of buying good coax (or open wire line), Making
sure the antenna is roughly the right impedance for the feedline (often
by some sort of matching network at the antenna, either built into the
antenna (Yagis) or explicit), and use a matching network (or amplifier
output network) at the shack end, and tune for maximum (Fwd
pwr-reflected pwr) on a directional wattmeter.

There's a bunch of assumptions embedded in the latter exceedingly
practical method. It essentially ignores the
"matching network" properties of the feed line and it assumes the
transmitter is a constant power constant impedance device. But it's
probably "good enough"


There are systems (particularly with feedlines that are < 1/2
wavelength) where the "per 100 meter" loss of the feedline in a matched
system could be high, but in YOUR particular system, the overall loss
might be lower. In the matched case V/I = Z0. In the non-matched case,
V/I might be something else - and feedlines have different "voltage
loss" (typically from dielectric losses) versus "current loss" (IR loss
in the conductors). This is why open wire line with a high Z0 is
popular: Essentially no dielectric loss, and the Z0 is high, so the
current is low, so the "loss per meter" is small, and even in a highly
"mismatched" case with a tuner/matching network at the shack, the
circulating currents are low enough that the loss is low.