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?

p.
--

The BBC: licenced at public expense to spread lies.

Paul,
The most obvious method would be to measure the open-circuit RF output
voltage, and then measure the output voltage with a known load. The output
impedance is a simple calculation of the ratio of the voltages.
However, depending on the vintage and quality of the generator, the
impedance is likely to change with frequency, and possibly even with output
level. For source-impedance-sensitive measurements, it's generally a good
idea to put a small amount of fixed resistive attenuation at the output
(6-10 dB) in order to "fix" the impedance.

Joe
W3JDR

"Paul Burridge" wrote in message
...
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?

p.
--

The BBC: licenced at public expense to spread lies.

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.
JP

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

"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)

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

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" 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)

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 ;-)?

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 ;-)?