On Sat, 15 Oct 2005 04:00:14 GMT, Cecil Moore wrote:
Who would approach a Bird and expect it to in the first place?
Someone who thinks reflections cannot be eliminated by 1/4WL
of thin-film?
Certainly one who thinks it does. And both having been disproved, it
stands to - well, let's just say that fulfilling that trite expression
with "reason" fulfills the cliche - but not the tenor. ;-)

On Sat, 15 Oct 2005 03:37:16 GMT, Cecil Moore wrote:

Owen Duffy wrote:

Cecil Moore wrote:
and not to be a myth at all. There's 104.17 watts of forward power
through the Bird and 4.17 watts of reflected power back through the
Bird. Why does the Bird ignore those actual power values?

I did not report or even measure such a thing.

Since I realized the Bird forms a Z0-match at its output that
statement should be ammended to say: There 104.17 watts of forward
energy flowing in the 75 ohm coax on each side of the Bird and 4.17
watts of reflected energy flowing in the 75 ohm coax on each side
of the Bird. Why does the Bird ignore those actual power values
existing in the actual system?

100W--tuner---75 ohm coax---Bird--1/2WL 75 ohm coax--50 ohm load
Pfor=104.17W-- Pfor=104.17W-- 100W delivered
--Pref=4.17W --Pref=4.17W

The Bird is not reading the proper values of forward and reflected
power on the 75 ohm coax because it is embedded in a non-50 ohm
environment.

This has nothing to do with the stated myth: Measurements with a Bird
43 of the conditions on the Thruline section are invalid unless it has
some minimum length of 50 ohm line on both sides of itself.

Nothing in the myth stated or implied direct application of the
measured conditions on the thruline section to any other connected (or
disconnected for that matter) transmission line, that is entirely your
construction.

It is a diversion Cecil.

Owen
--

Sorry, that should be:

"that when algebraicly
Actually, that should be "algebraically"
Interesting thread though. BYW, is the Bird using the Bruene type bridge
or some other topology?
Alan

On Sat, 15 Oct 2005 18:26:30 +1000, Alan Peake
wrote:


Sorry, that should be:

"that when algebraicly
Actually, that should be "algebraically"

Thanks. There were some other typos along the way, but that was
clearly a spelling mistake and the spell checker didn't find it.

Interesting thread though. BYW, is the Bird using the Bruene type bridge

Is that BTW?

I understand that the Breune type bridge is one of the bothways
detector designs with a untapped toroidal current transformer. I doubt
the Bird sampler element is of that type.

It appears to have a flat section of line that is parallel to the coax
centre conductor and is presumably capacitively and inductively
coupled, and it uses some form of frequency compensation to give it
broadband response. You rotate the sampler element for measurement of
the opposite direction.

Someone here may have dismantled one to see how it works.

I suspect that all of these probe designs try to sample net V and I at
a point, and the extent by which they depart from a point sample
limits their upper frequency of usefulness.

Though there are several designs, they seem to broadly fall into two
main types, those where the sampler response is inherently
proportional to frequency (though they may be compensated as in the
Bird elements) or those where they are inherently broadband (as the
Bruene circuit).

Trust you are well. I heard you on 40m the other day, but only just!
Propagation has been pretty shabby.

Owen
--

Richard Clark wrote:

Cecil Moore wrote:
Someone who thinks reflections cannot be eliminated by 1/4WL
of thin-film?

Certainly one who thinks it does. And both having been disproved, ...

I guess you will take that delusion to your grave.
--
73, Cecil http://www.qsl.net/w5dxp

Owen Duffy wrote:
Nothing in the myth stated or implied direct application of the
measured conditions on the thruline section to any other connected (or
disconnected for that matter) transmission line, that is entirely your
construction.

It is a diversion Cecil.

No, it is the point that Reg and I were discussing long before
you entered the thread. Reg made the same same point a couple
of days ago.
--
73, Cecil http://www.qsl.net/w5dxp

Alan Peake wrote:
Interesting thread though. BYW, is the Bird using the Bruene type bridge
or some other topology?

The Bird 43 manual is available at http://www.bird-electronic.com
--
73, Cecil http://www.qsl.net/w5dxp

Owen Duffy wrote:
This has nothing to do with the stated myth: Measurements with a Bird
43 of the conditions on the Thruline section are invalid unless it has
some minimum length of 50 ohm line on both sides of itself.

Would you be willing to make the same statement about an MFJ wattmeter?
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
om...
Owen Duffy wrote:
This has nothing to do with the stated myth: Measurements with a Bird
43 of the conditions on the Thruline section are invalid unless it has
some minimum length of 50 ohm line on both sides of itself.

Would you be willing to make the same statement about an MFJ wattmeter?

now your are just trying to muddy the waters... i wouldn't trust an mfj to
measure anything!

On Sat, 15 Oct 2005 14:26:43 GMT, Cecil Moore wrote:
I guess you will take that delusion to your grave.
Yet more guessing?