Re: To Students.

Brian Reay wrote:

"Reg Edwards" <g4fgq.regp@xxxxxxxxxxxxxxxxx> wrote in message news:dltbk2$fde$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

"Brian Reay" wrote


So, what does a SWR meter display? (A question you've never answered 

by the

way.)


===================================
Dear Brian,

I'm sick and tired of telling you.  Get yourself some better reading
glasses.

The meter displays whether or not the transmitter is loaded with a
resistive 50 ohms.



You've still not said what is being measured.

I'll put you out of your misery.

An SWR Bridge measures the value of the ratio
between the load impedance and 50 ohms, always
expressed as a number greater than 1. It doesn't
show which way the ratio is. Nor does it show
the character of the complex impedance of the
load. It cannot distinguish between a purely
resistive mismatch and either direction of
complex mismatch.

Below 50 ohms load it measures - 50ohms/load impedance magnitude,
above 50 ohms it measures - load impedance magnitude/50ohms.

And it is a bridge. The measured quantity is a degree of imbalance.

Which is what Reg said.

OK?

Experiment:

Use your SWR Bridge to measure the 'SWR' of a
33ohm and a 75 ohm resistive load directly
coupled to the output side of the bridge.
Now try a 100 ohm and a 25 ohm load. Use
non inductive resistors.

Consider where the standing wave might be
under such circumstances.

vy 73

Andy, M1EBV
.

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