What consequence for 75 Ohm output into 50 Ohm input ?

P

Peter

Guest
How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.
 
Peter wrote:

How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.
Click to expand...
Perhaps the simplest thing is to make a 75 ohm to 50 ohm T matching network
with a fixed attentuation.

Ian
 
Ian Bell <ian@redtommo.com> wrote in
news:c1gk0j$1ihd1p$2@ID-225948.news.uni-berlin.de:

Peter wrote:

How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's
?

Thanks
Peter.

Perhaps the simplest thing is to make a 75 ohm to 50 ohm T matching
network with a fixed attentuation.

Ian
Click to expand...
There are commercial L-pads to convert from 75 to 50ohm,with enough
bandwidth and low VSWR for much higher frequencies.
This generator only goes to 21 Mhz,IIRC.

--
Jim Yanik
jyanik-at-kua.net
 
vandaalen@chello.nl (Peter) wrote in message news:<8b298d71.0402241045.393c5a92@posting.google.com>...
How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.
Click to expand...
Well, I mean : how should I read the ( in 75 Ohm output calibrated ) dBm scales
when the HP 3336 generator's 75 Ohm output is inputted into 50 Ohm devices ?

I guess there is a calculating factor for it.
VSWR will be 1.5 ( right ? ) i.e. 4% power transfer loss.
Is it as simple as that I can multiply the output scales with a 100/104 fraction ?

Peter.
 
vandaalen@chello.nl (Peter) wrote in
news:8b298d71.0402241841.23e5bd3a@posting.google.com:

vandaalen@chello.nl (Peter) wrote in message
news:<8b298d71.0402241045.393c5a92@posting.google.com>...
How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's
?

Thanks
Peter.

Well, I mean : how should I read the ( in 75 Ohm output calibrated )
dBm scales when the HP 3336 generator's 75 Ohm output is inputted into
50 Ohm devices ?

I guess there is a calculating factor for it.
VSWR will be 1.5 ( right ? ) i.e. 4% power transfer loss.
Is it as simple as that I can multiply the output scales with a
100/104 fraction ?

Peter.
Click to expand...
A commercial L-pad should have the db loss marked on it,or in the datasheet
that originally came along with it.
Then you just subtract the db loss of the L-pad from the output db's.

--
Jim Yanik
jyanik-at-kua.net
 
If you terminate a 75 ohm generator with 75 ohms, the open circuit output
voltage will drop by 6db right? Now if you terminate the same generator with
50 ohms the open circuit output should drop by
7.9588 db. The difference (7.9588 - 6) = 1.9588db.
bg
Peter wrote in message <8b298d71.0402241841.23e5bd3a@posting.google.com>...
vandaalen@chello.nl (Peter) wrote in message
news:<8b298d71.0402241045.393c5a92@posting.google.com>...
How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.

Well, I mean : how should I read the ( in 75 Ohm output calibrated ) dBm
scales
when the HP 3336 generator's 75 Ohm output is inputted into 50 Ohm devices
?

I guess there is a calculating factor for it.
VSWR will be 1.5 ( right ? ) i.e. 4% power transfer loss.
Is it as simple as that I can multiply the output scales with a 100/104
fraction ?

Peter.
Click to expand...
 
On 24 Feb 2004 10:45:47 -0800, vandaalen@chello.nl (Peter) wrote:

How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.
Click to expand...

75 ohm gen >----[ 43.3 ohms]--------o---------->50 ohm DUT
|
86.6 ohms
|
///

use a 43.3 ohm resistor in series and a 86.6 ohm in shunt to gnd...







Remove "HeadFromButt", before replying by email.
 
maxfoo <maxfooHeadFromButt@punkass.com> wrote in
news:berq30doh2755g7h5fncnbr1j7qv3bv4nf@4ax.com:

On 24 Feb 2004 10:45:47 -0800, vandaalen@chello.nl (Peter) wrote:

How should I recalibrate a HP 3336A 75 Ohm output signal generator (
with better than .2 dB output resolution ) for use into 50 Ohm DUT's ?

Thanks
Peter.


75 ohm gen >----[ 43.3 ohms]--------o---------->50 ohm DUT
|
86.6 ohms
|
///

use a 43.3 ohm resistor in series and a 86.6 ohm in shunt to gnd...
Click to expand...

Then use a power meter to determine the output level and L-pad loss.
If you use SMD resistors and a PCB,you ought to achieve a decent BW.

--
Jim Yanik
jyanik-at-kua.net
 
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