On Sun, 05 Sep 2004 19:06:03 -0700, Wes Stewart wrote:


| On Sun, 5 Sep 2004 12:18:09 +0000 (UTC), "Reg Edwards"
| wrote:
|snip
| |There are NO directional couplers at HF. They are as scarce as real swr
| |meters. So they cannot be used in futile attempts to explain what really
| |happens at HF.
| |
| |You're next move will be to drag in scattering-matrices.
|
| Why not. I have used an HP3577 network analyzer with an S-parameter
| test set that was specified to work over the frequency range of 100 Hz
| to 200 Mhz.
|
| I guess the guys at HP didn't realize that you can't do this.
|
|=================================
|
|Wes,
|
|Why do USA citizens invariably introduce the type numbers of their
|favourite, indeed worshipped articles when they have not the slightest
|bearing on an argument. To base one's position on a lifeless piece of
|hardware rather than logic is surely unsafe.

Well, I cannot speak for all US citizens and *invariably* is a little
too all encompassing for me. But I suppose it's similar to declaring
so unequivocally and "logically" that there are NO directional
couplers at HF. When presented with a real-life instrument that
includes these non-existant couplers that you refer to, you wish to
attack and belittle the presenter.

If you don't know what an HP 3577 is, you might ask in a civil manner,
in which case I would say that it is a vector network analyzer,
covering the frequency range of 5 Hz to 200 MHz that was widely used
in this country as well as around the world.

An accessory to the instrument is an S-parameter test set that offered
the ability to measure full two-port parameters over the frequency
range of 100 Hz to 200 MHz, which last time I checked, includes the hf
spectrum.


|What on Earth is an HP3577?

See above.

|In the whole of my career I have never heard of
|the number 3577.

Clearly, you have lived a sheltered professional life.

|Is it a prime? Traditionally, in the UK, the letters HP
|on the side of a savoury sauce bottle stand for "Houses of Parliament"

Perhaps, but me thinks that the sauce that you are more familiar with
says something different.
|
|Unless a 3577 can unambiguously measure the swr on a non-existent
|transmission line I'm afraid its presence will serve only to further
|agravate the argument.

Surprising to you perhaps, yes it can.

And Reg, in conjunction with the HP-8405 Vector Voltmeter, the HP-778D dual
directional coupler can measure SWR from 1 MHz to 1 GHz with no transmission
line whatever. This combination is the workhorse of my RF Lab.

Walt