Hi to W1RS,
I don't know you very well but
I hope you understand my post was mostly jest. I figured any one with a
"W" call sign would understand.
Nice meeting you,
I hope to talk more about non-50 ohm measurements.
I have a lot of 300 - 450 ohm ladder line work to do. And I am just
starting out with a VNA. So I will be asking for help.
I also want to take a closer look at the "some what popular" wide band low
Z to high Z -"half wave"- end fed toroid transformer and see if there is
room for improvement. I have used a bob-tailcurtain on 80meters in the past
and had amazing results. I have also used the half of a bob-tail and I
recommend it. Some People have no idea what can be done on 80m day after
day with less than 100 watts right thru a sunspot minimum. Those are my
ambitions, more later. I am just starting out with using a VNA an still
have lots of reading to do.
Nels Nelsen
NE7LS
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On Tue, Feb 18, 2020, 6:53 AM W1RS <Deflatermaus@...> wrote:
Nels, I should have said Hi-Z broadband transmission lines. Of course the
tube amp situation is as Dave stated. I went to
to calculate the spacing
for the ladder line.
I was amazed at how rapidly it increases with the impedance. The
line-to-line capacitance requirements just get really small. According to
the equations presented,
300 Ohms --> 0.3 "
450 Ohms --> 1"
700 Ohms --> 8.5 "
1000 Ohms --> 105"
I'm very impressed with the nanoVNA, but with the 50 Ohm bridge design, I
would not expect to achieve good accuracy at measuring at greater than 10
times the bridge Z, especially at higher frequencies.
