Richard Clark wrote:

Cecil Moore wrote:
The Bird is in error when it reports the SWR to be 1:1.

This is the poor carpenter blaming his tools.

Exactly! You got my point. It is operators who refuse to
recognize the errors in the Bird's readings and report
a bogus SWR as "correct" who are at fault.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Jim Kelley wrote:


Cecil Moore wrote:

The actual SWR on a lossless line doesn't change. Yet, in another
posting, I showed that moving the Bird 1/4WL closer to the load
caused a reported SWR change by the Bird from 1:1 to 2.25:1. How
could both results possibly be right?


You need to keep thinking about that. What if they are both right?


Here's the example sans the Bird. Between the tuner output
and the load, where exactly is the actual SWR = 1:1 and where
exactly is the actual SWR = 2.25:1? Answer: nowhere!

XMTR--tuner---1 WL 75 ohm coax---50 ohm load

And the answer would be different still in this circuit.

XMTR---1/4 WL 75 ohm coax---50 ohm load

Amazin', what happens when you change the circuit!

ac6xg

"Reg Edwards" wrote
CB-ers and novices are unlikely to learn anything from it.

================================

And it appears some professional IEEE engineers and university
professors also remain in difficulty.

Just because, from it's sales blurb and scale markings, an instrument
is purported to measure SWR with forward and reflected power, should
not be taken as being the gospel truth. It can be highly misleading.
And from this newsgroup it seems it is!

There's still some left in the bottle. Hic! Hic!
----
Reg.

On Thu, 13 Oct 2005 17:27:01 GMT, Cecil Moore wrote:

Richard Clark wrote:

Cecil Moore wrote:
The Bird is in error when it reports the SWR to be 1:1.

This is the poor carpenter blaming his tools.

Exactly! You got my point. It is operators who refuse to
recognize the errors in the Bird's readings

There was no error in the reading beyond the inherent ±5% specified as
the meter movement's. Owen no where at any time makes any appeal to
measuring or presenting SWR so the following claim is entirely
fabricated to present something not under his, my, or other poster's
consideration:

and report a bogus SWR as "correct" who are at fault.

Persistence in wedging a new picture into a valuable frame does not
make it a classic portrait by a master of the craft. This finger
painting being offered is no more notable than yet another tacky Elvis
on velvet.

Jim Kelley wrote:


Cecil Moore wrote:

Here's the example sans the Bird. Between the tuner output
and the load, where exactly is the actual SWR = 1:1 and where
exactly is the actual SWR = 2.25:1? Answer: nowhere!

XMTR--tuner---1 WL 75 ohm coax---50 ohm load

And the answer would be different still in this circuit.

XMTR---1/4 WL 75 ohm coax---50 ohm load

No, it wouldn't. The answer is exactly the same. *NOWHERE* is
the SWR 1:1 or 2.25:1. In both examples, the SWR on the coax
is 1.5:1. The SWR is *always* set by the relationship of Z0
to the load. In both examples above, that relationship is
*identical*.

Amazin', what happens when you change the circuit!

Z0 didn't change. The load didn't change. Therefore, the
SWR didn't change. What exactly do you think changed?
--
73, Cecil http://www.qsl.net/w5dxp

Richard Clark wrote:

Cecil Moore wrote:
Exactly! You got my point. It is operators who refuse to
recognize the errors in the Bird's readings

There was no error in the reading beyond the inherent ±5% specified as
the meter movement's.

The Bird is supposed to measure power. The Bird's forward
power readings are in error unless used in a 50 ohm
environment.

I previously talked about using a hammer on a screw. I was
hoping even you could understand that metaphor without me
having to explain it to you.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Z0 didn't change. The load didn't change. Therefore, the
SWR didn't change. What exactly do you think changed?

I think the circuit changed. Don't you? I also think that if you
change the circuit, it's possible to measure the effect of that change.
The meter measures what takes place at its insertion point in the
circuit. What you seem to be upset about is that it might not in every
case accurately display the conditions at some arbitrary position away
from its insertion point. Like within a shorted quarterwave stub for
example. Are you still unwilling to accept that the meter itself can
present a perturbation?

ac6xg

On Thu, 13 Oct 2005 18:48:05 GMT, Cecil Moore wrote:

The Bird is supposed to measure power. The Bird's forward
power readings are in error
That has not been demonstrated by Owen's example. Elvis is getting
moldy, and the velvet is becoming tattered at the frame where it was
nailed in.

"Cecil Moore" wrote in message
om...
Dave wrote:
well DUH! obviously if you want to measure swr on a 450 ohm ladder line
you don't use a 50 ohm bird!

Yes, now you are getting it. If you want to measure SWR on a 75 ohm
coax line, you don't use a 50 ohm Bird. I couldn't have said it
better myself.
--

then why are you complaining about it not showing the swr on the 75 ohm
coax?? you should know that no one in their right mind would expect it to
do that.

"Cecil Moore" wrote in message
. ..
Jim Kelley wrote:


Cecil Moore wrote:

Here's the example sans the Bird. Between the tuner output
and the load, where exactly is the actual SWR = 1:1 and where
exactly is the actual SWR = 2.25:1? Answer: nowhere!

XMTR--tuner---1 WL 75 ohm coax---50 ohm load

And the answer would be different still in this circuit.

XMTR---1/4 WL 75 ohm coax---50 ohm load

No, it wouldn't. The answer is exactly the same. *NOWHERE* is
the SWR 1:1 or 2.25:1. In both examples, the SWR on the coax
is 1.5:1. The SWR is *always* set by the relationship of Z0
to the load. In both examples above, that relationship is
*identical*.

Amazin', what happens when you change the circuit!

Z0 didn't change. The load didn't change. Therefore, the
SWR didn't change. What exactly do you think changed?
--
73, Cecil http://www.qsl.net/w5dxp

obviously the problem here is that cecil thinks he is the only one that
knows better than to try to measure reflected power with a 50 ohm meter in a
75 ohm coax.