Re: HP 8341B RF sweeper has reduced output
At least the HPAK step attenuators are high performance.? ?I checked the 40 GHz ones out not too long ago versus similar ones from JFW, and there was no comparison!? HPAK beat JFW on every single spec!? Price for used HPAK 84904L and 84906L on eBay is similar to new JFW 50P-2072.? Let the buyer beware!
Jim Ford
Sent from my T-Mobile 4G LTE Device
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-------- Original message -------- From: Lothar baier <Lothar@...> Date: 3/3/22 7:22 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] HP 8341B RF sweeper has reduced output
?
Here is the parts breakdown of the parts available for the step attenuators
?
Sent from for Windows
?
Those o rings always been a pain and agilent did not learn the lesson because the newer 50GHz attenuators had the same issue !? agilent used to sell the o-rings as well as the push rods with o-rings as parts but you had to go into their
parts system online to find the part numbers as the manual did not give any of the information I guess they figured nobody would fool around with this kind of stuff
?
Sent from for Windows
?
?
I would look at the solenoids before cleaning the pad contacts.? My?
guess is that one of the plungers is stuck due to a deteriorated "o"?
ring.
Cheers!
Bruce
Quoting Steve - Home <steve-krull@...>:
> In the 8340/41 the output power indicator is measuring power before?
> the attenuator so will indicated ¡°requested¡± power, not actual?
> output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with?
> the phase locked 3.7 GHz oscillator.
> Remove the front panel, remove the attenuator, loosen the end caps?
> of the attenuator (8 Allen screws) remove the nuts from the SMA?
> connectors for RF in and out, remove the name plate, remove the 20?
> hex head screws holding the front plate and SMA connectors and?
> GENTLY pry the front plate off. The attenuator pads are attached to?
> the front plate. Clean the contacts for each pad with 99.9%?
> isopropyl alcohol. Clean the through lines the same way. Usually?
> clears the problem.
>
> Steve
> WB0DBS
>
>
>
>> On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
>>
>> ?Hi all
>>
>> My HP 8341B sweeper looks like output down 10dbm~13dbm from?
>> requested level output...measured on a Boonton 4200 power meter?
>> know good.
>>
>> I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other?
>> bands. I suspect an output step attenuator problem? a 10db pad?
>> "stuck"?
>>
>> Looking at power meter at right of front panel on 8341B I see it?
>> matches requested power output...shouldnt be showing -10~13dbm down?
>> from requested value if there is an attenuator problem since that?
>> value is measured at output?
>>
>> Anybody very familiar with these HP sweepers suggestions/tricks to?
>> save me time to address this? Ive fixed lots of test equipment but?
>> never this 8341B and its a *75 pound beast* that id like to fix and?
>> put back where it lives asap...its no fun to handle, flip over and?
>> move...
>>
>> Thanks all
>>
>
>
>
?
|
Re: HP 8341B RF sweeper has reduced output
?
Here is the parts breakdown of the parts available for the step attenuators
?
Sent from for Windows
?
toggle quoted message
Show quoted text
Those o rings always been a pain and agilent did not learn the lesson because the newer 50GHz attenuators had the same issue !? agilent used to sell the o-rings as well as the push rods with o-rings as parts but you had to go into their
parts system online to find the part numbers as the manual did not give any of the information I guess they figured nobody would fool around with this kind of stuff
?
Sent from for Windows
?
?
I would look at the solenoids before cleaning the pad contacts.? My?
guess is that one of the plungers is stuck due to a deteriorated "o"?
ring.
Cheers!
Bruce
Quoting Steve - Home <steve-krull@...>:
> In the 8340/41 the output power indicator is measuring power before?
> the attenuator so will indicated ¡°requested¡± power, not actual?
> output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with?
> the phase locked 3.7 GHz oscillator.
> Remove the front panel, remove the attenuator, loosen the end caps?
> of the attenuator (8 Allen screws) remove the nuts from the SMA?
> connectors for RF in and out, remove the name plate, remove the 20?
> hex head screws holding the front plate and SMA connectors and?
> GENTLY pry the front plate off. The attenuator pads are attached to?
> the front plate. Clean the contacts for each pad with 99.9%?
> isopropyl alcohol. Clean the through lines the same way. Usually?
> clears the problem.
>
> Steve
> WB0DBS
>
>
>
>> On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
>>
>> ?Hi all
>>
>> My HP 8341B sweeper looks like output down 10dbm~13dbm from?
>> requested level output...measured on a Boonton 4200 power meter?
>> know good.
>>
>> I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other?
>> bands. I suspect an output step attenuator problem? a 10db pad?
>> "stuck"?
>>
>> Looking at power meter at right of front panel on 8341B I see it?
>> matches requested power output...shouldnt be showing -10~13dbm down?
>> from requested value if there is an attenuator problem since that?
>> value is measured at output?
>>
>> Anybody very familiar with these HP sweepers suggestions/tricks to?
>> save me time to address this? Ive fixed lots of test equipment but?
>> never this 8341B and its a *75 pound beast* that id like to fix and?
>> put back where it lives asap...its no fun to handle, flip over and?
>> move...
>>
>> Thanks all
>>
>
>
>
?
|
Re: HP 8341B RF sweeper has reduced output
?
turns out they still sell em for $20? ,? the picture also provides a good illustration of the pushrod with the rings
?
Sent from for Windows
?
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From: Bruce via groups.io
Sent: Thursday, March 3, 2022 9:04 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8341B RF sweeper has reduced output
?
I would look at the solenoids before cleaning the pad contacts.? My?
guess is that one of the plungers is stuck due to a deteriorated "o"?
ring.
Cheers!
Bruce
Quoting Steve - Home <steve-krull@...>:
> In the 8340/41 the output power indicator is measuring power before?
> the attenuator so will indicated ¡°requested¡± power, not actual?
> output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with?
> the phase locked 3.7 GHz oscillator.
> Remove the front panel, remove the attenuator, loosen the end caps?
> of the attenuator (8 Allen screws) remove the nuts from the SMA?
> connectors for RF in and out, remove the name plate, remove the 20?
> hex head screws holding the front plate and SMA connectors and?
> GENTLY pry the front plate off. The attenuator pads are attached to?
> the front plate. Clean the contacts for each pad with 99.9%?
> isopropyl alcohol. Clean the through lines the same way. Usually?
> clears the problem.
>
> Steve
> WB0DBS
>
>
>
>> On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
>>
>> ?Hi all
>>
>> My HP 8341B sweeper looks like output down 10dbm~13dbm from?
>> requested level output...measured on a Boonton 4200 power meter?
>> know good.
>>
>> I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other?
>> bands. I suspect an output step attenuator problem? a 10db pad?
>> "stuck"?
>>
>> Looking at power meter at right of front panel on 8341B I see it?
>> matches requested power output...shouldnt be showing -10~13dbm down?
>> from requested value if there is an attenuator problem since that?
>> value is measured at output?
>>
>> Anybody very familiar with these HP sweepers suggestions/tricks to?
>> save me time to address this? Ive fixed lots of test equipment but?
>> never this 8341B and its a *75 pound beast* that id like to fix and?
>> put back where it lives asap...its no fun to handle, flip over and?
>> move...
>>
>> Thanks all
>>
>
>
>
?
|
Re: HP 8341B RF sweeper has reduced output
Those o rings always been a pain and agilent did not learn the lesson because the newer 50GHz attenuators had the same issue !? agilent used to sell the o-rings as well as the push rods with o-rings as parts but you had to go into their
parts system online to find the part numbers as the manual did not give any of the information I guess they figured nobody would fool around with this kind of stuff
?
Sent from for Windows
?
toggle quoted message
Show quoted text
From: Bruce via groups.io
Sent: Thursday, March 3, 2022 9:04 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8341B RF sweeper has reduced output
?
I would look at the solenoids before cleaning the pad contacts.? My?
guess is that one of the plungers is stuck due to a deteriorated "o"?
ring.
Cheers!
Bruce
Quoting Steve - Home <steve-krull@...>:
> In the 8340/41 the output power indicator is measuring power before?
> the attenuator so will indicated ¡°requested¡± power, not actual?
> output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with?
> the phase locked 3.7 GHz oscillator.
> Remove the front panel, remove the attenuator, loosen the end caps?
> of the attenuator (8 Allen screws) remove the nuts from the SMA?
> connectors for RF in and out, remove the name plate, remove the 20?
> hex head screws holding the front plate and SMA connectors and?
> GENTLY pry the front plate off. The attenuator pads are attached to?
> the front plate. Clean the contacts for each pad with 99.9%?
> isopropyl alcohol. Clean the through lines the same way. Usually?
> clears the problem.
>
> Steve
> WB0DBS
>
>
>
>> On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
>>
>> ?Hi all
>>
>> My HP 8341B sweeper looks like output down 10dbm~13dbm from?
>> requested level output...measured on a Boonton 4200 power meter?
>> know good.
>>
>> I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other?
>> bands. I suspect an output step attenuator problem? a 10db pad?
>> "stuck"?
>>
>> Looking at power meter at right of front panel on 8341B I see it?
>> matches requested power output...shouldnt be showing -10~13dbm down?
>> from requested value if there is an attenuator problem since that?
>> value is measured at output?
>>
>> Anybody very familiar with these HP sweepers suggestions/tricks to?
>> save me time to address this? Ive fixed lots of test equipment but?
>> never this 8341B and its a *75 pound beast* that id like to fix and?
>> put back where it lives asap...its no fun to handle, flip over and?
>> move...
>>
>> Thanks all
>>
>
>
>
?
|
Re: HP 8341B RF sweeper has reduced output
I would look at the solenoids before cleaning the pad contacts. My guess is that one of the plungers is stuck due to a deteriorated "o" ring.
Cheers!
Bruce
Quoting Steve - Home <steve-krull@...>:
toggle quoted message
Show quoted text
In the 8340/41 the output power indicator is measuring power before the attenuator so will indicated ¡°requested¡± power, not actual output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with the phase locked 3.7 GHz oscillator.
Remove the front panel, remove the attenuator, loosen the end caps of the attenuator (8 Allen screws) remove the nuts from the SMA connectors for RF in and out, remove the name plate, remove the 20 hex head screws holding the front plate and SMA connectors and GENTLY pry the front plate off. The attenuator pads are attached to the front plate. Clean the contacts for each pad with 99.9% isopropyl alcohol. Clean the through lines the same way. Usually clears the problem.
Steve
WB0DBS
On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
?Hi all
My HP 8341B sweeper looks like output down 10dbm~13dbm from requested level output...measured on a Boonton 4200 power meter know good.
I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other bands. I suspect an output step attenuator problem? a 10db pad "stuck"?
Looking at power meter at right of front panel on 8341B I see it matches requested power output...shouldnt be showing -10~13dbm down from requested value if there is an attenuator problem since that value is measured at output?
Anybody very familiar with these HP sweepers suggestions/tricks to save me time to address this? Ive fixed lots of test equipment but never this 8341B and its a *75 pound beast* that id like to fix and put back where it lives asap...its no fun to handle, flip over and move...
Thanks all
|
Re: HP 8341B RF sweeper has reduced output
If you have dirty pads usually your loss will roll off at lower frequencies and then normalize at higher bands , this is because the dirt in essence is a series capacitor creating a high pass characteristic ,? you can check this by putting
a 50ohm termination on one side of your attenuator and connect a multimeter on the other side between center conductor and ground and then measure the resistance for each pad setting , it should read close to 50ohm , if it is higher than this points towards
dirty pads or a blown pad !
In my years fixing those beasts back at tucker the most common issue I saw was bad o-rings .
If you pull off the cover of the attenuator cover and look at the solenoids you see the plungers that actuate the contacts , you see little white pushrods that are connected to those plungers , there should be a black o-ring visible on
top and bottom ,? usually over the years the rubber becomes bridle and then falls apart , if this happens the contacts no longer make sufficient contact and the attenuator fails .
Agilent used to sell those as spare parts but you can also find them at watchmakers supply stores as they are used as sprocket gaskets , the company I ordered them from was otto frey/borrell if I remember correctly but this was like 20
years ago
One more hint on the cleaning part ,? avoid using regular cotton swabs as they fuzz , use techspray swabs or you can also use surgical swabs you can get at medical supply stores
?
Sent from for Windows
?
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In the 8340/41 the output power indicator is measuring power before the attenuator so will indicated ¡°requested¡± power, not actual output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with the phase locked 3.7 GHz oscillator.?
Remove the front panel, remove the attenuator, loosen the end caps of the attenuator (8 Allen screws) remove the nuts from the SMA connectors for RF in and out, remove the name plate, remove the 20 hex head screws holding the front plate and SMA connectors
and GENTLY pry the front plate off. The attenuator pads are attached to the front plate. Clean the contacts for each pad with 99.9% isopropyl alcohol. Clean the through lines the same way. Usually clears the problem.?
On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
?Hi all
My HP 8341B sweeper looks like output down 10dbm~13dbm from requested level output...measured on a Boonton 4200 power meter know good.?
I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other bands. I suspect an output step attenuator problem? a 10db pad "stuck"?
Looking at power meter at right of front panel on 8341B I see it matches requested power output...shouldnt be showing -10~13dbm down from requested value if there is an attenuator problem since that value is measured at output?
Anybody very familiar with these HP sweepers suggestions/tricks to save me time to address this? Ive fixed lots of test equipment but never this 8341B and its a *75 pound beast* that id like to fix and put back where it lives asap...its no fun to handle, flip
over and move...
Thanks all
|
Yes, cables called "null modem" tend to have pins 2 and 3 swapped, IIRC.? Apparently you don't want one of those.? Those in this group more familiar with datacom than I am can expand on this.? HTH
Jim Ford
Sent from my T-Mobile 4G LTE Device
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-------- Original message -------- From: Lothar baier <Lothar@...> Date: 3/3/22 5:47 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Make sure its wired 1 to 1
?
Sent from for Windows
?
Ordered a 6ft cable, will report back with my results. I have tried slow sweep, less points, zero span. No luck.
|
Make sure its wired 1 to 1
?
Sent from for Windows
?
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Ordered a 6ft cable, will report back with my results. I have tried slow sweep, less points, zero span. No luck.
|
Re: HP 8341B RF sweeper has reduced output
In the 8340/41 the output power indicator is measuring power before the attenuator so will indicated ¡°requested¡± power, not actual output power. Band 0 is 10 MHz - 2.3 GHz, the swept LO is mixed with the phase locked 3.7 GHz oscillator.? Remove the front panel, remove the attenuator, loosen the end caps of the attenuator (8 Allen screws) remove the nuts from the SMA connectors for RF in and out, remove the name plate, remove the 20 hex head screws holding the front plate and SMA connectors and GENTLY pry the front plate off. The attenuator pads are attached to the front plate. Clean the contacts for each pad with 99.9% isopropyl alcohol. Clean the through lines the same way. Usually clears the problem.?
toggle quoted message
Show quoted text
On Mar 3, 2022, at 5:56 PM, charlesterrebonne@... wrote:
?Hi all
My HP 8341B sweeper looks like output down 10dbm~13dbm from requested level output...measured on a Boonton 4200 power meter know good.?
I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other bands. I suspect an output step attenuator problem? a 10db pad "stuck"?
Looking at power meter at right of front panel on 8341B I see it matches requested power output...shouldnt be showing -10~13dbm down from requested value if there is an attenuator problem since that value is measured at output?
Anybody very familiar with these HP sweepers suggestions/tricks to save me time to address this? Ive fixed lots of test equipment but never this 8341B and its a *75 pound beast* that id like to fix and put back where it lives asap...its no fun to handle, flip over and move...
Thanks all
|
On Thursday, March 3, 2022, 04:40:49 PM PST, H Kapa via groups.io <hcapela@...> wrote:
Hi Jim Adney,
I have a 200CD Ser.605- working on my bench and a few days ago in the middle of another repair my 200CD signal failed, how is it possible!! it was completely silent, it was left to wait for further analysis,
In time there I decided to check carefully, the DC voltages were present, but fluctuating in relation to the earth, result R40 of 15K / 10W open, I replaced it with an equivalent but with must the improvised fixing and nothing like the original.
?
So, I ask if you don't have an R40 to supply? , I know that transport is always the most expensive but can you still do it to Lisbon / Portugal?
Best Regards?
H Capela?
|
Hi Jim Adney,
I have a 200CD Ser.605- working on my bench and a few days ago in the middle of another repair my 200CD signal failed, how is it possible!! it was completely silent, it was left to wait for further analysis,
In time there I decided to check carefully, the DC voltages were present, but fluctuating in relation to the earth, result R40 of 15K / 10W open, I replaced it with an equivalent but with must the improvised fixing and nothing like the original.
?
So, I ask if you don't have an R40 to supply? , I know that transport is always the most expensive but can you still do it to Lisbon / Portugal?
Best Regards?
H Capela?
|
HP 8341B RF sweeper has reduced output
Hi all
My HP 8341B sweeper looks like output down 10dbm~13dbm from requested level output...measured on a Boonton 4200 power meter know good.?
I rarely use it above 1Ghz... IIRC <2Ghz is band 0 didnt test other bands. I suspect an output step attenuator problem? a 10db pad "stuck"?
Looking at power meter at right of front panel on 8341B I see it matches requested power output...shouldnt be showing -10~13dbm down from requested value if there is an attenuator problem since that value is measured at output?
Anybody very familiar with these HP sweepers suggestions/tricks to save me time to address this? Ive fixed lots of test equipment but never this 8341B and its a *75 pound beast* that id like to fix and put back where it lives asap...its no fun to handle, flip over and move...
Thanks all
|
Ordered a 6ft cable, will report back with my results. I have tried slow sweep, less points, zero span. No luck.
|
Re: Spectrum analyser in a high traffic strong signal environment
IIRC, Metamagnetics considers the 4 dB the insertion loss.? In an interference-limited receiver, that would probably be acceptable.
Jim
Sent from my T-Mobile 4G LTE Device
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-------- Original message -------- From: "Brooke Clarke via groups.io" <brooke@...> Date: 3/3/22 2:11 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] Spectrum analyser in a high traffic strong signal environment
Hi Jim: Interesting.? It seems that the weak (desired) signal is attenuated about 4dB while the strong signal is knocked down to the limiting level.? See: https://patents.google.com/patent/US20190267960 The device makes use of circulators/isolators to maintain a reasonable VSWR. I looked since a simple diode limiter does the same thing, except it knocks down all signals and has a high VSWR. -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs.
|
Re: Spectrum analyser in a high traffic strong signal environment
Hi Jim:
Interesting.? It seems that the weak (desired) signal is attenuated about 4dB while the strong signal is knocked down to the limiting level.? See:
The device makes use of circulators/isolators to maintain a reasonable VSWR.
I looked since a simple diode limiter does the same thing, except it knocks down all signals and has a high VSWR.
--
Have Fun,
Brooke Clarke, N6GCE
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.
|
Seems ike you could mitigate the problem by slowing the sweep down.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
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This just FYI !
I talked to a friend of mine this morning who was working as a test engineer at raytheon for 20 years , they used 8510 systems and in some applications had to use the testsets in a different location than the VNA itself.
His comment was that HP recommended to him not to exceed 5ft length on the control cable for the 8516A to ensure reliabile operation
On Mar 2, 2022, at 23:00, Lothar baier via groups.io <Lothar@...> wrote:
?Regardless it is best practice to keep cable lengths at a minimum, DB25 cables retail from $5 to $20 depending on make and length so its not cost prohibitive to aquire a short cable
On Mar 2, 2022, at 22:15, Bruce via groups.io <bruce@...> wrote:
?Thanks - Excellent, now he can test his cable.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Pin 4
Pin 10
Pin 11
Pin 17
Wired straight through !
I am using a DB25 cable from Amazon 3ft works flawless
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 9:57 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
If you know the cable connections please POST it to the board. That
way, he can check his cable and "fix" it if necessary.
BTW - IS the cable straight through? If so, which conductors are needed?
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
I bought mine on ebay for $800 , spend quite a bit of time trying to
figure out the cable
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 7:13 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Seems like the wrong wearing due to a cross over or some other
"defect" could cause intermittent operation.
How about using a break out box to look at the signals. I've never
owned an 8516 (owned most of the others). Just looked in my 8510
service manual set and have no 8516 schematic - do have for most of
the others - He could look at the output from the doubler to see if it
is working - possible connector damage is a risk.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
There is no schematic for the 8516 only a few block diagrams , the
switching isn¡¯t done by relays but rather with pin diodes inside the
brick , the doubler control board is buttoned up on the Doubler ,
the only information to be gathered from the service manual is that
there are 4 control lines that go to a PAL that acts as adress
decoder , from there are 5 lines one goes to the doubler to switch
it in and out the other 4 lines go to a block labeled filter control
which outputs 5 lines that go to the actual doubler block so there
is quite a bit of switching going on but there is no info on the
switch points or details on the filters .
Having a crossover cable definatly might be a concern but he also
mentioned that it used to work ¡°intermittent¡± so that¡¯s also
something to think about
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:48 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Sure but it is comparatively slow - Normal 8510C sweep is relatively
slow, and the problem can be avoided by only weeping 50-20 and say
25-40GHz.
I think the best first step is to look at the doubler switching module
to see if the relay is actually switching the doubler in. I don't
seem to have a schematic diagram for the 8516, but hopefully, HP
included a LED on the module?
In any case need to check the cable connections and determine whether
the doubler is being energized - actually, maybe just watching the +
supply to the doubler itself might work.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Disagree with you on this, dont forget that the synthesizer is swept
so if you do a 45MHz to 40GHz sweep the doubler is switched in and
out constantly so your DC now becomes a squarewave , also the
control signal not only switches the doubler but also switches in
and out filters to clean up the signal so there is some activity
going on those control lines !
One way to find out would be to tack a scope probe on the control
lines and look at the shape of the control signals
On Mar 2, 2022, at 18:30, Bruce via groups.io
<bruce@...> wrote:
?Missed that - the 20 ft cable seems NOT likely to be a problem -
these ar DC control signals. I recall some discussion that it is a
straight through cable without cross over based on looking at 8341
and 8516 schematic diagrams - I think that I'd focus on
investigating the wiring of the cable.
1) Determine which conductors are used and be certain that the
cable has those conductors 1-1 without cross over.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
He mentioned earlier in this thread that its only 20-40GHz but he
also mentioned using a 20ft cable ? which could be the problem, I
am not sure what the control interface is , the part number of the
control cable says RS232 and there are 4 lines connected in the
testset BUT the doubler control uses a PAL as a decoder so I think
it¡¯s a parallel interface and having a 20ft cable could be a bit
much
Sent from Mail<>
for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:21 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Does the IF error occur below 20 GHz ?? If not, the doubler is
suspect - if so, look at the switching or the test set.
Nexg step would be to try and look at the test set VTO. It is
difficult because they pipe it directly into the samplers.
Cheers!
Bruce
Quoting ratn9ne@...:
Wow you guys are fast to help!
Here is some more info: error is only from 20-40GHz, so it has
something to do with the doubler I assume. Any span or frequency in
this range has this error. I have seen >20GHz work for a little
while but only randomly. My next idea is a shorter DB25 cable as
mine is about 20 feet long. Tried turning up the LO power coming in
on the sweeper with no luck. I can't find a replacement doubler on
ebay to test with. These must be very rare. Can they be serviced?
This display/sweeper/control box setup has been tested with an 8515
and no errors at all.
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This just FYI !
I talked to a friend of mine this morning who was working as a test engineer at raytheon for 20 years , they used 8510 systems and in some applications had to use the testsets in a different location than the VNA itself.
His comment was that HP recommended to him not to exceed 5ft length on the control cable for the 8516A to ensure reliabile operation
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On Mar 2, 2022, at 23:00, Lothar baier via groups.io <Lothar@...> wrote:
?Regardless it is best practice to keep cable lengths at a minimum, DB25 cables retail from $5 to $20 depending on make and length so its not cost prohibitive to aquire a short cable
On Mar 2, 2022, at 22:15, Bruce via groups.io <bruce@...> wrote:
?Thanks - Excellent, now he can test his cable.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Pin 4
Pin 10
Pin 11
Pin 17
Wired straight through !
I am using a DB25 cable from Amazon 3ft works flawless
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 9:57 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
If you know the cable connections please POST it to the board. That
way, he can check his cable and "fix" it if necessary.
BTW - IS the cable straight through? If so, which conductors are needed?
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
I bought mine on ebay for $800 , spend quite a bit of time trying to
figure out the cable
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 7:13 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Seems like the wrong wearing due to a cross over or some other
"defect" could cause intermittent operation.
How about using a break out box to look at the signals. I've never
owned an 8516 (owned most of the others). Just looked in my 8510
service manual set and have no 8516 schematic - do have for most of
the others - He could look at the output from the doubler to see if it
is working - possible connector damage is a risk.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
There is no schematic for the 8516 only a few block diagrams , the
switching isn¡¯t done by relays but rather with pin diodes inside the
brick , the doubler control board is buttoned up on the Doubler ,
the only information to be gathered from the service manual is that
there are 4 control lines that go to a PAL that acts as adress
decoder , from there are 5 lines one goes to the doubler to switch
it in and out the other 4 lines go to a block labeled filter control
which outputs 5 lines that go to the actual doubler block so there
is quite a bit of switching going on but there is no info on the
switch points or details on the filters .
Having a crossover cable definatly might be a concern but he also
mentioned that it used to work ¡°intermittent¡± so that¡¯s also
something to think about
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:48 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Sure but it is comparatively slow - Normal 8510C sweep is relatively
slow, and the problem can be avoided by only weeping 50-20 and say
25-40GHz.
I think the best first step is to look at the doubler switching module
to see if the relay is actually switching the doubler in. I don't
seem to have a schematic diagram for the 8516, but hopefully, HP
included a LED on the module?
In any case need to check the cable connections and determine whether
the doubler is being energized - actually, maybe just watching the +
supply to the doubler itself might work.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Disagree with you on this, dont forget that the synthesizer is swept
so if you do a 45MHz to 40GHz sweep the doubler is switched in and
out constantly so your DC now becomes a squarewave , also the
control signal not only switches the doubler but also switches in
and out filters to clean up the signal so there is some activity
going on those control lines !
One way to find out would be to tack a scope probe on the control
lines and look at the shape of the control signals
On Mar 2, 2022, at 18:30, Bruce via groups.io
<bruce@...> wrote:
?Missed that - the 20 ft cable seems NOT likely to be a problem -
these ar DC control signals. I recall some discussion that it is a
straight through cable without cross over based on looking at 8341
and 8516 schematic diagrams - I think that I'd focus on
investigating the wiring of the cable.
1) Determine which conductors are used and be certain that the
cable has those conductors 1-1 without cross over.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
He mentioned earlier in this thread that its only 20-40GHz but he
also mentioned using a 20ft cable ? which could be the problem, I
am not sure what the control interface is , the part number of the
control cable says RS232 and there are 4 lines connected in the
testset BUT the doubler control uses a PAL as a decoder so I think
it¡¯s a parallel interface and having a 20ft cable could be a bit
much
Sent from Mail<>
for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:21 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Does the IF error occur below 20 GHz ?? If not, the doubler is
suspect - if so, look at the switching or the test set.
Nexg step would be to try and look at the test set VTO. It is
difficult because they pipe it directly into the samplers.
Cheers!
Bruce
Quoting ratn9ne@...:
Wow you guys are fast to help!
Here is some more info: error is only from 20-40GHz, so it has
something to do with the doubler I assume. Any span or frequency in
this range has this error. I have seen >20GHz work for a little
while but only randomly. My next idea is a shorter DB25 cable as
mine is about 20 feet long. Tried turning up the LO power coming in
on the sweeper with no luck. I can't find a replacement doubler on
ebay to test with. These must be very rare. Can they be serviced?
This display/sweeper/control box setup has been tested with an 8515
and no errors at all.
|
Re: HP 1727A CRO: Problem with the vertical output amplifier.
Switching the input coupling to GND makes no difference as far as I can tell.
Also, does anybody have any recommendations for mosfets to use for a replacement circuit? or important specs at least.
|
Re: Keysight 3458A Front panel grounding clip
Just made a few calls to Keysight and 1460-1311 grounding clip is definitely not orderable.
I have the dimensions of the clip so I will try and manufacture a clip out of BeCu sheet metal.
Thanks,
Victor
|
OT: Leader instruments manual
Hi everyone and sorry for the OT, but this group has the best chances
to help in this case.
Does anyone happen to have the Leader LVG-1600 manual? Even only the
user manual would greatly help.
Thanks in advance and best regards.
Frank
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H Kapa
Willy
Alex_03
