Well, I guess help is not wanted for whatever reason. I'd rather
offer sincerely and be refused than not offer and learn later that it
was in order.

Regards,
Tom

Richard Clark wrote in message . ..
On 18 Aug 2003 09:37:59 -0700, (Tom Bruhns) wrote:

Richard,

If you do indeed need help, it's far more help than I can give you.
My posting was not in jest, nor was it to poke fun at you or your
postings. I was dead serious about it.

Cheers,
Tom


Hi Tom,

Yes, I have noticed the 30 cent jump in the cost of gas. ;-)

How about lunch at Lake Stevens then? I drove that for a couple of
years too, back when your outfit was called HP. I worked in Larry
Whatley and Nick Pendergas's group during the Marysville to L.S. move
(to set a time frame). 1,000,000 lines of Pascal FFT code in that
project. It was fun and I still have a lot of drawings of waveforms
generated.

For those who are interested in the nuances of FFT's (and why their
own implementation transforms lack resolution or dynamic range); my
tenure provided me with a wealth of insight that is commonly
unimplemented in current discussions here and generally in trade
publications.

73's
Richard Clark, KB7QHC

"Tom Bruhns" wrote:

...... Perhaps
Reg is right. Perhaps we SHOULD quit calling
it an SWR meter and instead call it a "Transmitter
Load Indicator" (or perhaps transmitter load error
indicator).

I propose that we call it a "Reflected Energy
Guessimator", or REG for short.

Jim, K7JEB k7jeb(at)arrl(dot)net
Glendale, AZ

Has it not yet occurred to you the impedance of the usual amateur's
transmitter changes when the load impedance is changed?

In the present context this not only makes a mess of maximum-power theorems,
conjugate matches, and referrals to renouned authors, it also reduces the
years and gigabtres of 'learned' arguments on this newsgroup to nonsense.

However, it's been great entertainment. Long may it contiunue. ;o)
---
Reg, G4FGQ

On Fri, 22 Aug 2003 03:59:13 +0000 (UTC), "Reg Edwards"
wrote:

Has it not yet occurred to you the impedance of the usual amateur's
transmitter changes when the load impedance is changed?


Few seem willing to put a -um- a number to it. They could then
respond coyly "change from what?"

The assembled throng not only didn't give you quarter, they didn't
even give you ha' pence. ;-)

I share your amusement tho' and if I had a glass of wine, I would
click it to the monitor in front of me.

73's
Richard Clark, KB7QHC

Few seem willing to put a -um- a number to it.

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

Rich, As a qualified engineer, and someone who has participated in futile
discussions, how would YOU obtain a number for it?

Such a number must exist.

Richard's numbers are average for what seems to be the RF component of
the waveform. It does not include any variations cause by modulation
characteristics.

A single number does not exist!! An average value for my voice
characteristics will be different from an average value with your voice
characteristics, etc.

The spectral and intensity characteristics of each voice is different
and will cause the instantaneous and average V/I ratio in the finals to
vary. Therefore, a single number does not exist.

It may be possible to develop an equation with variable functions for
spectral and intensity density functions to modulate the output but each
solution would be unique.

A nice thevinin model would be a constant voltage, example 12 volts dc,
with a dynamically varying source resistor. The source resistor has two
components in the modulation scheme: 1) the RF frequency variation,
constant frequency, 2) and the second term the audio spectral power
density of my voice. This would be loaded by a constant 50 ohm load.

Anyway, it's nice to think about. Averages are much easier to work with
though!

DD, W1MCE

Reg Edwards wrote:

Few seem willing to put a -um- a number to it.



[SNIP]

Such a number must exist.

Richard Clark wrote:
"I keyed down and made sure the excitation was disconnected---."

Supposing you were measuring the impedance the source shunts its output
with, and supposing your amplifier is linear so it can be used for AM
and SSB, and supposing that it is Class AB or Class B for more
efficiency than Class A, and supposing that it has a small amount of
forward bias to reduce crossover distortion, you should measure a much
higher impedance while idling than when the transmitter puts full power
into a load.

The output impedance has a meaning at maximum power output. This can be
determined by trying different loads to find the load that gets the most
power from the transmitter. The source impedance is its conjugate.

Best regards, Richard Harrison, KB5WZI

On Fri, 22 Aug 2003 14:02:35 GMT, Dave Shrader
wrote:

A single number does not exist!! An average value for my voice
characteristics will be different from an average value with your voice
characteristics, etc.

Hi Dave,

Are you one of those who whistles, hums, and recites the Gettysburg
Address into the mike while tuning up? Many on the band would offer
you as an example of Infernal Resistance. ;-)

73's
Richard Clark, KB7QHC

On Fri, 22 Aug 2003 09:48:56 -0500 (CDT),
(Richard Harrison) wrote:

Richard Clark wrote:
"I keyed down and made sure the excitation was disconnected---."

Supposing you were measuring the impedance the source shunts its output
with, and supposing your amplifier is linear so it can be used for AM
and SSB, and supposing that it is Class AB or Class B for more
efficiency than Class A, and supposing that it has a small amount of
forward bias to reduce crossover distortion, you should measure a much
higher impedance while idling than when the transmitter puts full power
into a load.

This would be true of commercial equipment (that is for commercial
stations, not equipment sold commercially in the retail trade).


The output impedance has a meaning at maximum power output. This can be
determined by trying different loads to find the load that gets the most
power from the transmitter. The source impedance is its conjugate.

Best regards, Richard Harrison, KB5WZI

Hi Richard,

And that too was performed, as I described, consistent with others'
reports to their methods (much as you describe).

73's
Richard Clark, KB7QHC

"Richard Clark" said
Are you one of those who whistles, hums, and recites the Gettysburg
Address into the mike while tuning up?

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

"Patriotism is not enough". (Nurse Edith Cavel)