Re: A homemade diode power sensor for HP meters
In my connector search above, I didn't pay any attention to how the connector mounts onto the device.? For a new homebrew design, it probably doesn't matter.? But, if you are specifically trying to replace the connector in an existing HP power sensor unit, you might have to check if you needed a front-threaded or a rear-threaded panel mount connector.?
|
Re: A homemade diode power sensor for HP meters
The 12-pin circular connector used on the power sensors is an Amphenol.? The old part number was 91-T-3638.
Now, it's part of their "C 091 A/B/D" series circular connectors.? Several variations are listed in the Amphenol catalog:
https://www.amphenol-sine.com/pdf/catalog/C091Amphenol.pdf
Mouser has several slightly expensive options (a few of which appear in this link -- note that widening the Mouser search filter will supply more results):
It appears that an eBay seller is selling them at a lower price.? His text says they are the 12-pin versions, although his photo shows the 14-pin version.? It's hard to tell which of the two connectors he is selling.? However, it appears the two additional pins shouldn't matter since it's the female part of the connector -- you would leave those two extra pins unconnected.
|
Re: Measuring Phase with Agilent E5062A ENA
Dear Gedas,
There is a way round this you might find useful- reference line extension function; I used this on an 8753B to take out the delay in a long optical delay line.
Essentially, you sweep over a frequency range that the DUT is phase linear over.?
Then adjust reference line extension until you get flat phase.?
Then read off the extension in ns.?
Then calculate the phase shift from frequency and delay.
I have n’t checked whether the same function is available for E series analysers; it would be a pity, if not.
Regards,
Alwyn ??
_____________________________________________________
Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.
Tel.: +44 (0) 20 7376 4110
SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom. _____________________________________________________
|
Re: Measuring Phase with Agilent E5062A ENA
Have you tried displaying your results on a Smith chart?
Check out Dr Joel Dunsmore’s book, “Microwave Component Measurements” for more than you ever wanted to know on the subject.?
toggle quoted message
Show quoted text
On Nov 18, 2018, at 01:00, Gedas < w8bya@...> wrote:
Thanks for that. It does in fact say phase is
measured +/- 180 degrees. Earlier I ran a quick test using the
expanded phase format and I think it is in fact exactly what I
want. Below is the same cable swept from 100 MHz to 300 MHz. The
-90 degree and -180 degree points appear to be at the right
frequencies. So if it will help others, un-wrapping phase or
wrapping phase is very closely related to the expanded phase
display format option of this ENA model. Too bad the users
manual is useless in discussing these and so many other neat
features.
<expand-phase-enabled.png>
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 10:10 PM, nj902 wrote:
Gedas wrote: "Can someone point me to some reading material to
help me understand how to measure phase ..."
------------------------------------------------------------------------------------------------------------------------------------------
Look for references on "unwrapped phase" measurement / display.
Like:
|
Re: A homemade diode power sensor for HP meters
Yeah, that would be bad, essentially counterfeit sensors made from shells of fried ones.? And they would sort of work, just nowhere near spec.
toggle quoted message
Show quoted text
On 11/17/2018 6:34 PM, Dr. David Kirkby from Kirkby Microwave Ltd wrote: On Sat, 17 Nov 2018, 17:30 Peter Gottlieb <hpnpilot@... <mailto:hpnpilot@...> wrote:
This is an interesting project.? As you say the meters themselves are dirt
cheap.? I have seen blown sensors sold cheap as well and maybe it's
possible to
build your circuit into one of those which would have the advantage of
connectors and case already taken care of.? If a small inexpensive SM
board is
made to do this it could easily fit and be so inexpensive that it wouldn't
even
be worth the time to troubleshoot a failure, just replace the board if it
gets
blown out.
Peter
The worrying thing is the Chinese counterfeiters will probably do just that. eBay seller yixunhk springs to mind - someone called them the HP rebirthing centre. I can see them "rebirthing" power sensors. ?
Dave
|
Re: Measuring Phase with Agilent E5062A ENA
Thanks for that. It does in fact say phase is
measured +/- 180 degrees. Earlier I ran a quick test using the
expanded phase format and I think it is in fact exactly what I
want. Below is the same cable swept from 100 MHz to 300 MHz. The
-90 degree and -180 degree points appear to be at the right
frequencies. So if it will help others, un-wrapping phase or
wrapping phase is very closely related to the expanded phase
display format option of this ENA model. Too bad the users
manual is useless in discussing these and so many other neat
features.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 10:10 PM, nj902 wrote:
toggle quoted message
Show quoted text
Gedas wrote: "Can someone point me to some reading material to
help me understand how to measure phase ..."
------------------------------------------------------------------------------------------------------------------------------------------
Look for references on "unwrapped phase" measurement / display.
Like:
_._,_._,_
|
Re: WANTED: HP 606B Sig Gen RF Output Attenuator Module A10
Hi Graeme!!
Can you use a 606B attenuator assy, that needs a resistor or two replaced??? I have an attenuator that was replaced in a 606B, because it got across mains voltage and took out two resistors.? I saved it, intending to replace those resistors, but never have done that.? It functions except on higher output levels, and its complete.? Let me know.?
Kim,? W8ZV
Sent from my alcatel Fierce 4
|
Re: Measuring Phase with Agilent E5062A ENA
Gedas wrote: "Can someone point me to some reading material to help me understand how to measure phase ..."
------------------------------------------------------------------------------------------------------------------------------------------
Look for references on "unwrapped phase" measurement / display.
Like:
|
Re: WANTED: HP 606B Sig Gen RF Output Attenuator Module A10
1. Find an NOS A10 module (eBay or other). Not easy, probably expensive. 2. Buy another 606B being sold 'for parts' and scavenge A10 (hopefully it will be a good one). Shipping will be a major part of the cost if it has to come into Oz from the Outside World. 3. Get someone in the Outside World to find a parts 606B, remove A10, send it to you. Probably less expensive that shipping in a complete 606B.
Jeremy
On Sat, Nov 17, 2018 at 5:00 PM Graeme Dennes < gdennes@...> wrote: Needed to repair a 606B.
My preferred repair solution is to replace the faulty A10 attenuator module with a serviceable module.
The existing module has three coax cables hard-wired internally to it - input, output and cal output.
For identification purposes, I note the attenuator from the sig gen model 606A doesn't have the calibrator output connection, so is not a direct replacement.
Thanks for your help.
Graeme Dennes
Australia
|
Re: Measuring Phase with Agilent E5062A ENA
Not off hand.? I'll have to check with some friends and see if
there's anything in app notes or other reading.? Remember what I
just said..I've been retired too long!? :-)
The plane just went down for annual inspection, so it won't be
available for a while...? It's harder to do it in the winter,
especially when heat is hard to come by!
Daun
On 11/17/2018 9:15 PM, Gedas wrote:
Well the airfield across the road is always
ready for you <g>. Do you know of any good HP or other
source of reading material that may describe POS PHASE &
EXPANDED PHASE etc ?
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 9:12 PM, Daun Yeagley
wrote:
Indeed!
Yeah, unfortunately, the ENA won't do it.? Not sure if some of
the new ones will or not..... I've been retired too long!
Still have to get back up your way... maybe in the spring!
Daun
On 11/17/2018 9:06 PM, Gedas wrote:
Hi Daun....long time no chat. Yup
understand 100% but was hoping that the ENA had a function
to do that for me. There are some "VNA's" that will do
that for you. I guess this one will not hi-hi.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 8:54 PM, Daun
Yeagley wrote:
Gedas, what you are seeing is "phase wrap".? The detectors
in the VNA's can't resolve more than 360 degrees... 370
degrees looks the same as 10 degrees!
The only way you can do it is to count how many "wraps" you
have, IF you can do it in a continuous sweep with no bridges
over the wraps.
Hope this gets you started in understanding that!
Daun
On 11/17/2018 8:45 PM, Gedas
wrote:
Can someone point me to some reading material to help
me understand how to measure phase on my ENA?
I have the operators manual but it is not at all
helpful. In short I chose a simple ~19" length RG-223
coaxial jumper as a starting point to help me better
understand my instrument. I am having difficulty in
getting the display to show phase shifts great then 180
degrees even though the Y-axis is indicating I have
plenty of latitude, i.e., +/- 450 degrees etc.
I.e., below is a screen capture where I am showing the
phase shift thru that jumper at 104MHz.....back of the
napkin calculations show that in fact ~19" length of
V.F. 0.66 cable should provide -90 degrees phase shift:
Things even work well when I double the frequency to
208 MHz and obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I
would like to display phase shifts great then? -180
degrees. As soon as I go higher in frequency the plot
jumps up to a positive 180 degree phase shift.
I would like to know if I can setup my ENA to display
say -270 or -400 degree phase shifts. I have been using
PHASE under the display options and do see options for
POS PHASE, & EXPANDED PHASE. I was hoping expanded
phase would do what I wanted but it did not. The manual
does not discuss how to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
--
Daun E. Yeagley II, N8ASB
--
Daun E. Yeagley II, N8ASB
--
Daun E. Yeagley II, N8ASB
|
Re: Measuring Phase with Agilent E5062A ENA
Well the airfield across the road is always ready
for you <g>. Do you know of any good HP or other source of
reading material that may describe POS PHASE & EXPANDED
PHASE etc ?
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 9:12 PM, Daun Yeagley
wrote:
toggle quoted message
Show quoted text
Indeed!
Yeah, unfortunately, the ENA won't do it.? Not sure if some of the
new ones will or not..... I've been retired too long!
Still have to get back up your way... maybe in the spring!
Daun
On 11/17/2018 9:06 PM, Gedas wrote:
Hi Daun....long time no chat. Yup understand
100% but was hoping that the ENA had a function to do that
for me. There are some "VNA's" that will do that for you. I
guess this one will not hi-hi.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 8:54 PM, Daun Yeagley
wrote:
Gedas, what you are seeing is "phase wrap".? The detectors in
the VNA's can't resolve more than 360 degrees... 370 degrees
looks the same as 10 degrees!
The only way you can do it is to count how many "wraps" you
have, IF you can do it in a continuous sweep with no bridges
over the wraps.
Hope this gets you started in understanding that!
Daun
On 11/17/2018 8:45 PM, Gedas
wrote:
Can someone point me to some reading material to help me
understand how to measure phase on my ENA?
I have the operators manual but it is not at all helpful.
In short I chose a simple ~19" length RG-223 coaxial
jumper as a starting point to help me better understand my
instrument. I am having difficulty in getting the display
to show phase shifts great then 180 degrees even though
the Y-axis is indicating I have plenty of latitude, i.e.,
+/- 450 degrees etc.
I.e., below is a screen capture where I am showing the
phase shift thru that jumper at 104MHz.....back of the
napkin calculations show that in fact ~19" length of V.F.
0.66 cable should provide -90 degrees phase shift:
Things even work well when I double the frequency to 208
MHz and obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I
would like to display phase shifts great then? -180
degrees. As soon as I go higher in frequency the plot
jumps up to a positive 180 degree phase shift.
I would like to know if I can setup my ENA to display say
-270 or -400 degree phase shifts. I have been using PHASE
under the display options and do see options for POS
PHASE, & EXPANDED PHASE. I was hoping expanded phase
would do what I wanted but it did not. The manual does not
discuss how to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
--
Daun E. Yeagley II, N8ASB
--
Daun E. Yeagley II, N8ASB
|
Re: Measuring Phase with Agilent E5062A ENA
Indeed!
Yeah, unfortunately, the ENA won't do it.? Not sure if some of the
new ones will or not..... I've been retired too long!
Still have to get back up your way... maybe in the spring!
Daun
On 11/17/2018 9:06 PM, Gedas wrote:
Hi Daun....long time no chat. Yup understand
100% but was hoping that the ENA had a function to do that for
me. There are some "VNA's" that will do that for you. I guess
this one will not hi-hi.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 8:54 PM, Daun Yeagley
wrote:
Gedas, what you are seeing is "phase wrap".? The detectors in
the VNA's can't resolve more than 360 degrees... 370 degrees
looks the same as 10 degrees!
The only way you can do it is to count how many "wraps" you
have, IF you can do it in a continuous sweep with no bridges
over the wraps.
Hope this gets you started in understanding that!
Daun
On 11/17/2018 8:45 PM, Gedas wrote:
Can someone point me to some reading material to help me
understand how to measure phase on my ENA?
I have the operators manual but it is not at all helpful.
In short I chose a simple ~19" length RG-223 coaxial jumper
as a starting point to help me better understand my
instrument. I am having difficulty in getting the display to
show phase shifts great then 180 degrees even though the
Y-axis is indicating I have plenty of latitude, i.e., +/-
450 degrees etc.
I.e., below is a screen capture where I am showing the
phase shift thru that jumper at 104MHz.....back of the
napkin calculations show that in fact ~19" length of V.F.
0.66 cable should provide -90 degrees phase shift:
Things even work well when I double the frequency to 208
MHz and obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I would
like to display phase shifts great then? -180 degrees. As
soon as I go higher in frequency the plot jumps up to a
positive 180 degree phase shift.
I would like to know if I can setup my ENA to display say
-270 or -400 degree phase shifts. I have been using PHASE
under the display options and do see options for POS PHASE,
& EXPANDED PHASE. I was hoping expanded phase would do
what I wanted but it did not. The manual does not discuss
how to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
--
Daun E. Yeagley II, N8ASB
--
Daun E. Yeagley II, N8ASB
|
Re: Measuring Phase with Agilent E5062A ENA
Hi Daun....long time no chat. Yup understand 100%
but was hoping that the ENA had a function to do that for me.
There are some "VNA's" that will do that for you. I guess this
one will not hi-hi.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 11/17/2018 8:54 PM, Daun Yeagley
wrote:
toggle quoted message
Show quoted text
Gedas, what you are seeing is "phase wrap".? The detectors in the
VNA's can't resolve more than 360 degrees... 370 degrees looks the
same as 10 degrees!
The only way you can do it is to count how many "wraps" you have,
IF you can do it in a continuous sweep with no bridges over the
wraps.
Hope this gets you started in understanding that!
Daun
On 11/17/2018 8:45 PM, Gedas wrote:
Can someone point me to some reading material to help me
understand how to measure phase on my ENA?
I have the operators manual but it is not at all helpful. In
short I chose a simple ~19" length RG-223 coaxial jumper as a
starting point to help me better understand my instrument. I
am having difficulty in getting the display to show phase
shifts great then 180 degrees even though the Y-axis is
indicating I have plenty of latitude, i.e., +/- 450 degrees
etc.
I.e., below is a screen capture where I am showing the phase
shift thru that jumper at 104MHz.....back of the napkin
calculations show that in fact ~19" length of V.F. 0.66 cable
should provide -90 degrees phase shift:
Things even work well when I double the frequency to 208 MHz
and obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I would
like to display phase shifts great then? -180 degrees. As soon
as I go higher in frequency the plot jumps up to a positive
180 degree phase shift.
I would like to know if I can setup my ENA to display say
-270 or -400 degree phase shifts. I have been using PHASE
under the display options and do see options for POS PHASE,
& EXPANDED PHASE. I was hoping expanded phase would do
what I wanted but it did not. The manual does not discuss how
to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
--
Daun E. Yeagley II, N8ASB
|
Re: Measuring Phase with Agilent E5062A ENA
Gedas, what you are seeing is "phase wrap".? The detectors in the
VNA's can't resolve more than 360 degrees... 370 degrees looks the
same as 10 degrees!
The only way you can do it is to count how many "wraps" you have, IF
you can do it in a continuous sweep with no bridges over the wraps.
Hope this gets you started in understanding that!
Daun
On 11/17/2018 8:45 PM, Gedas wrote:
Can someone point me to some reading material to help me
understand how to measure phase on my ENA?
I have the operators manual but it is not at all helpful. In
short I chose a simple ~19" length RG-223 coaxial jumper as a
starting point to help me better understand my instrument. I am
having difficulty in getting the display to show phase shifts
great then 180 degrees even though the Y-axis is indicating I
have plenty of latitude, i.e., +/- 450 degrees etc.
I.e., below is a screen capture where I am showing the phase
shift thru that jumper at 104MHz.....back of the napkin
calculations show that in fact ~19" length of V.F. 0.66 cable
should provide -90 degrees phase shift:
Things even work well when I double the frequency to 208 MHz
and obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I would
like to display phase shifts great then? -180 degrees. As soon
as I go higher in frequency the plot jumps up to a positive 180
degree phase shift.
I would like to know if I can setup my ENA to display say -270
or -400 degree phase shifts. I have been using PHASE under the
display options and do see options for POS PHASE, & EXPANDED
PHASE. I was hoping expanded phase would do what I wanted but it
did not. The manual does not discuss how to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
--
Daun E. Yeagley II, N8ASB
|
Measuring Phase with Agilent E5062A ENA
Can someone point me to some reading material to help me
understand how to measure phase on my ENA?
I have the operators manual but it is not at all helpful. In
short I chose a simple ~19" length RG-223 coaxial jumper as a
starting point to help me better understand my instrument. I am
having difficulty in getting the display to show phase shifts
great then 180 degrees even though the Y-axis is indicating I have
plenty of latitude, i.e., +/- 450 degrees etc.
I.e., below is a screen capture where I am showing the phase
shift thru that jumper at 104MHz.....back of the napkin
calculations show that in fact ~19" length of V.F. 0.66 cable
should provide -90 degrees phase shift:
Things even work well when I double the frequency to 208 MHz and
obtain a ~180 degree phase shift:
The issue is when I go slightly higher in frequency I would like
to display phase shifts great then? -180 degrees. As soon as I go
higher in frequency the plot jumps up to a positive 180 degree
phase shift.
I would like to know if I can setup my ENA to display say -270 or
-400 degree phase shifts. I have been using PHASE under the
display options and do see options for POS PHASE, & EXPANDED
PHASE. I was hoping expanded phase would do what I wanted but it
did not. The manual does not discuss how to use these formats.
Gedas, W8BYA
Gallery at
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
|
Re: Readings from 436A power meter using 82357B USB-GPIB?
Hi Staffan
Yes, you need to meter to be in addressable mode (or as you say,
"normal").
If you use the interactive IO, you would use the "Send and Read"..?
Type the command to fetch the reading in the text box, and use the
"Send and Read" button, which will set the computer as the talker,
send the command, and then it sets it up so the meter is the
talker.? You should see the results show up in the history below.?
It puts the actual results there, with no additional formatting so
you can see exactly what it sends back.? Of course you can also do
it individually using the separate "Send Command" and "Read
Response" as well. The "Send and Read" just combines the two
actions.
What language do you plan to use for your program?
Daun
On 11/17/2018 4:52 PM, Staffan wrote:
Hello,
Just got hold of an old HP436A power meter and would like to do
some automated measurements. Controlling the instrument is simple
using the 82357B USB-GPIB module (I can set range etc), but
reading data? As a first step I'd like to test using Agilent
Interactive IO from Connection Expert. If that works, I'm fairly
sure I can get it working in a program also.?
The 436 is set to NORMAL, i.e., not TALK ONLY. It does have the
HP-IB option 022 installed. My guess is that I need to address the
instrument to Talk in some other way than the "Read Response" used
in Interactive IO.
Anyone with experience of this?
Regards,
? Staffan
--
Daun E. Yeagley II, N8ASB
|
WANTED: HP 606B Sig Gen RF Output Attenuator Module A10
Needed to repair a 606B.
My preferred repair solution is to replace the faulty A10 attenuator module with a serviceable module.
The existing module has three coax cables hard-wired internally to it - input, output and cal output.
For identification purposes, I note the attenuator from the sig gen model 606A doesn't have the calibrator output connection, so is not a direct replacement.
Thanks for your help.
Graeme Dennes
Australia
|
Re: Issue with homemade diode power sensor for HP meters
Hi Tobias!?
Great experiment. Now add C2 & C3, c6,c7,c5 & c8.? These caps are part of the AC circuit and are used for balance in the autozero (C2 & C3). HP did not put in parts they did not need!
I have not studied the 436 input amp like you have, but would comment that the 220 Hz chopper frequency that switches Q1 & Q2 on/off alternatively needs to be accommodated in the bipolar AC amp. Also I note no source of DC for the bipolar to run on, it needs current from somewhere so it is getting it probably thru a negative bias on the emitter wrt the collector from the 436A otherwise how does the BJT work? In the emitter leg is a thermistor to compensate ambient mount temp. You have a pot there instead. I would think that you would want to adjust the detected voltage level before the FET gate circuit for calibration purposes.
I am sure the thermocouple arrangement produced a very small voltage.
I think a dead mount with your new input circuit is a great place to continue the experiment from. Re-use their carefully designed amplifier/fet gate circuit.
VBR & 73
Jeff Kruth
WA3ZKR
In a message dated 11/17/2018 12:49:37 PM Eastern Standard Time, tobias.pluess@... writes:
@Peter
thanks. Yes, exactly, the meters themselves are really cheap. I currently don't have access to some blown 8481A or similar sensors, so I cannibalized a sensor cable :-( because the connectors seem to be HP specific ones and are not available e.g. at Mouser or so.
But yes, as soon as I have a working circuit, I will it design such that it fits into the normal housing for those power sensors. I also thought of milling my own housing which would be similar to the original HP housing anyways.
The cool stuff is that Agilent and Keysight still use the same interface (at least for some power meters) as far as I know, so the sensor should work with any of those!
@Ed
?thanks also. Yes, I tried to study on the interface between the 436 and the power sensor. The resistor you are talking about is called the mount resistor in the 8481A manual. Here is the general schematic of this sensor:
The service manual tells which resistor value is used for the different ranges. I think it will be possible on the homemade sensor to add a little switch to change the mount resistor value and therefore the range the meter uses - such, the same sensor could be used for different power ranges. The 436A power ranges are very limited, as far as I remember.
However, what I don't understand in the interface between the meter and the sensor is how the autozero circuit works, and I am also a bit unsure about the working principle of the amplifier formed by Q1 in the sensor (see schematic) and the OpAmp in the meter. Do you know more details about how it works?
Best
Tobias HB9FSX
|
Re: A homemade diode power sensor for HP meters
Dr. David Kirkby from Kirkby Microwave Ltd
On Sat, 17 Nov 2018, 17:30 Peter Gottlieb < hpnpilot@... wrote: This is an interesting project.? As you say the meters themselves are dirt
cheap.? I have seen blown sensors sold cheap as well and maybe it's possible to
build your circuit into one of those which would have the advantage of
connectors and case already taken care of.? If a small inexpensive SM board is
made to do this it could easily fit and be so inexpensive that it wouldn't even
be worth the time to troubleshoot a failure, just replace the board if it gets
blown out.
Peter
The worrying thing is the Chinese counterfeiters will probably do just that. eBay seller yixunhk springs to mind - someone called them the HP rebirthing centre. I can see them "rebirthing" power sensors. ?
Dave
|
Re: A homemade diode power sensor for HP meters
Hi Tobias, I looked at the OP again, and realized that you already knew about the "mount" resistor - I didn't notice that the first time. I grabbed that 8484A manual pdf that Orin linked - thanks Orin, I have lots of 8484As, and the manual somewhere, but can never seem to find it. Now I have a fresh copy.
Anyway, after refreshing my memory on these sensors, and looking also at the 8481A schematic, I'd recommend studying both types - the TC and diode models have a different arrangement for the auto-zeroing function. The circuit you posted puts the AZ feedback to the detector, as in the 8481A TC circuit, but that won't work right. With the TC type, it is a low impedance source, so the AZ current can go through, and offset the signal. With a diode detector, you should use a circuit like in the 8484A, which applies it to the ground-side JFET switch in the chopper. The diode detector is a high impedance source, so you don't want to put the AZ feedback current there.
Good luck,
Ed
|
bownes
Jeremy Nichols
