Roy Lewallen wrote:
A transmission line can be very lossy, yet have a completely real
characteristic impedance.

That's what I thought. Is RG-174 one of those transmission lines?

Maybe even give you a break from thinking about waves of average power
bouncing about.

At least with average power, one cannot violate the conservation of
energy principle by creating instantaneous energy in a passive load. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:
Roy Lewallen wrote:

A transmission line can be very lossy, yet have a completely real
characteristic impedance.


That's what I thought. Is RG-174 one of those transmission lines?

No. Distortionless lines are specially made, or periodically loaded with
fixed components to achieve distortionless characteristics.

Incidentally, I recently carefully measured the Z0 of nine pieces of
RG-58 type cables at 10 MHz. R varied from 48.1 to 57.2 ohms, and X from
-0.67 to -2.32 ohms. I made one measurement at 1 MHz, on a cable whose
Z0 at 10 MHz was 49.0 - j0.69 at 10 MHz. That cable's Z0 at 1 MHz was
50.7 - j2.05 ohms. I wasn't able to make good measurements below 1 MHz
with my setup.

. . .

Roy Lewallen, W7EL

Roy Lewallen wrote:

Cecil Moore wrote:

Roy Lewallen wrote:
A transmission line can be very lossy, yet have a completely real
characteristic impedance.

That's what I thought. Is RG-174 one of those transmission lines?

No. Distortionless lines are specially made, or periodically loaded with
fixed components to achieve distortionless characteristics.

Incidentally, I recently carefully measured the Z0 of nine pieces of
RG-58 type cables at 10 MHz. R varied from 48.1 to 57.2 ohms, and X from
-0.67 to -2.32 ohms.

Assuming 57.2 - j2.32 ohms Z0, our 50 ohm SWR meters may be off
by 15%? Could this be the answer to Richard C's SWR readings?
I suggested that as a possibility early on but he dismissed it.
--
73, Cecil http://www.qsl.net/w5dxp



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There could be quite a number of reasons Richard's readings aren't
indicating what he thinks, and this is certainly one of them. Of one
thing I'm certain -- the reason is something other than actual SWR being
modified by source impedance.

And yes, our SWR meters can easily be that far off when attempting to
measure the real SWR on real cables. Good thing it doesn't matter, huh?

Roy Lewallen, W7EL

Cecil Moore wrote:

Assuming 57.2 - j2.32 ohms Z0, our 50 ohm SWR meters may be off
by 15%? Could this be the answer to Richard C's SWR readings?
I suggested that as a possibility early on but he dismissed it.