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-   -   Measuring RF output impedance (https://www.radiobanter.com/homebrew/22946-measuring-rf-output-impedance.html)

John Fields May 1st 04 09:44 PM

On Sat, 01 May 2004 17:03:26 GMT, Jan Panteltje
wrote:

On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


---
Without doing a conjugate match and accounting for the impedance of
the voltmeter and the load, the best he'll be able to do is _assume_
that what he measures is what he's really got.

--
John Fields

Frank Bemelman May 1st 04 10:37 PM

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)



Frank Bemelman May 1st 04 10:37 PM

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)



John Fields May 1st 04 10:55 PM

On Sat, 1 May 2004 23:37:26 +0200, "Frank Bemelman"
wrote:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.


---
LOL!


--
John Fields

John Fields May 1st 04 10:55 PM

On Sat, 1 May 2004 23:37:26 +0200, "Frank Bemelman"
wrote:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.


---
LOL!


--
John Fields

Jan Panteltje May 2nd 04 12:48 AM

On a sunny day (Sat, 1 May 2004 23:37:26 +0200) it happened "Frank Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.

Why that?



Jan Panteltje May 2nd 04 12:48 AM

On a sunny day (Sat, 1 May 2004 23:37:26 +0200) it happened "Frank Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.

Why that?



Frank Bemelman May 2nd 04 01:06 AM

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 1 May 2004 23:37:26 +0200) it happened "Frank

Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul

Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and

measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.


Why that?


I expect amplitudes to double or at least rise, after
removing a load. Just nitpicking ;)


--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)




Frank Bemelman May 2nd 04 01:06 AM

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 1 May 2004 23:37:26 +0200) it happened "Frank

Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul

Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and

measure
again.
If it is half, it is 50, else do the math.


If it is half, you've got a funny generator.


Why that?


I expect amplitudes to double or at least rise, after
removing a load. Just nitpicking ;)


--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)




Jan Panteltje May 2nd 04 02:15 AM

On a sunny day (Sun, 2 May 2004 02:06:09 +0200) it happened "Frank Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 1 May 2004 23:37:26 +0200) it happened "Frank

Bemelman"
wrote in
:

"Jan Panteltje" schreef in bericht
...
On a sunny day (Sat, 01 May 2004 14:19:59 +0100) it happened Paul

Burridge
wrote in
:

Hi,

I have a spare RF signal generator that has an unmarked output from a
type of socket I've never seen before. What's the simplest way of
establishing its output impedance? I've had a few ideas but no doubt
someone out there will know of something better, since I always seem
to end up making unnecessary work for myself.
Any suggestions?

Load it with 50 Ohms, and measure output voltage, remove load and

measure
again.
If it is half, it is 50, else do the math.

If it is half, you've got a funny generator.


Why that?


I expect amplitudes to double or at least rise, after
removing a load. Just nitpicking ;)

Yes - sentence construction could have been more clear,
it should have been inferred as 'If it is half *before you removed it*
now that would be wrong too, 'If it WAS half' OK.
No, actually it was correct, cause 'it' referred to the first measurement.
Did you collect many nits while picking ;-)?



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