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E4401B No 50MHZ Cal signal
开云体育Greetings, ? I have an Agilent E4401B with option 1DP (75 ohm input) and option A4H (GPIB interface) that I recently found at a swap meet. ? It powers up, displays a trace, and when I apply a test signal to the input, I can see it on the display – so far so good.? The only downside at this point is a persistent message that an alignment is necessary. ? The problem is that the alignment procedure fails.? After running an “align now” the noise floor is off the top of the screen.? I have also noticed that when selecting the internal 50 MHZ source, I do not see a corresponding signal on the screen.? This leads me to believe that the internal 50 mhz signal is not getting generated, causing the alignment procedure to turn the internal gain up way too high.? ? I have the component level schematics for the device, and have confirmed that on the RF assembly, the 2nd VCO is not receiving power because the “TEST MUX” – U56 is not getting enabled – All of the MUX lines (MUX_EN, MUX_0-MUX_2) are all at 0 v.? ? This is where I’m stuck – I see that U55 (Fractional Divider) has connections the MUX pins, but have no idea what tells it to place the MUX into a given state.? I can’t tell if this is a logic/software issue, cabling, or a bad U55. ? I’m hoping that someone here with more familiarity with these instruments has some insight as to what might be causing this, and next steps I should take to figure out the issue. ? Thanks! ? Mike Williams |
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Are you using 75 ohm components to calibrate it? You do realize that it will not work with 50 ohm components? On Sat, Mar 30, 2019 at 12:50 PM Michael Williams <mike@...> wrote:
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开云体育Hi Peter, ? I am aware of the differences between a 75 ohm input and 50 ohm input.? I have a 50 to 75 ohm impedance matching pad that I will be using on the input when measuring signals with a 50 ohm source.? I know this is not ideal, but will work for the things I plan to do with this gear. ? The issue I am having at this time is that the *internal* 50 mhz calibration signal is not getting generated, causing issues during the alignment procedure.? Unfortunately, on this model, the input is switched internally to the calibration signal, so I can’t even use an external signal to get through the alignment. ? Thanks, ? Mike ? From: <[email protected]> on behalf of "peter bunge via Groups.Io" <bunge.pjp@...> ? Are you using 75 ohm components to calibrate it? You do realize that it will not work with 50 ohm components? ? On Sat, Mar 30, 2019 at 12:50 PM Michael Williams <mike@...> wrote:
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The only advice I can offer is not to adjust anything until you fix the problem. I don't have this instrument. Hopefully you have a good block diagram and a description to figure it out. You are lucky to have the schematics. Peter On Sat, Mar 30, 2019 at 1:06 PM Michael Williams <mike@...> wrote:
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Hello Mike, I would first check out that Local Oscillator, I suspect your's is not there.? If I recall the cal signal is derived from the root source (YIG LO) which is fed as a reference into the 1st converter? via direct or through a LO Distribution amp.? This LO rhythm needs to be around +12 to +15 dbm in level.? Best of luck! Jon?
On Saturday, March 30, 2019, 12:06:13 PM CDT, Michael Williams <mike@...> wrote:
Hi Peter, ? I am aware of the differences between a 75 ohm input and 50 ohm input.? I have a 50 to 75 ohm impedance matching pad that I will be using on the input when measuring signals with a 50 ohm source.? I know this is not ideal, but will work for the things I plan to do with this gear. ? The issue I am having at this time is that the *internal* 50 mhz calibration signal is not getting generated, causing issues during the alignment procedure.? Unfortunately, on this model, the input is switched internally to the calibration signal, so I can’t even use an external signal to get through the alignment. ? Thanks, ? Mike ? From: <[email protected]> on behalf of "peter bunge via Groups.Io" <bunge.pjp@...> ? Are you using 75 ohm components to calibrate it? You do realize that it will not work with 50 ohm components? ? On Sat, Mar 30, 2019 at 12:50 PM Michael Williams <mike@...> wrote:
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开云体育I’m just trying to get the unit to do its own automatic internal alignment by doing selecting the “system->Alignment->Align Now” menu option.? I am not tweaking stuff manually.? I know the perils of trying to adjust or align things without the proper equipment or documentation.? I have done alignments and adjustments on radio equipment, in the past and have the equipment to do so. ? Unfortunately, for the unit to complete this process, it needs its internal 50 MHZ calibration signal, which is not getting generated.? Without it , during the automated alignment process, the unit increases the gain in the IF module to the point of being unusable.? This is the problem I am trying to solve.? Does anybody have any idea as to why the internal signal is dead?? My original post outlines the diagnostic tests I’ve done so far. ? ? From: <[email protected]> on behalf of "rpoz28cam via Groups.Io" <rpoz28cam@...> ? I? have to agree with Peter,? please do not adjust any of those "loose screws"? it will be the end of life for that one unless you're ready to get real serious with band pass filtering alignment and the likes.?? ? JM |
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Hi Mike,
I do not have my CLIP (it's at work) but I recently repaired a couple of these ESA's, although different issue. (LO UNLOCK error) As I recall, the 50 MHz is generated by a dedicated PLL that also generates the 10 MHz reference. I think it's a 100 MHz PLL that's dived by 2 and also by 10. The 1st step is to verify the 10 MHz out is present. (back of the unit) Then use the I/O menu to enable the 50 MHz. If that is not there, you have greatly narrowed down the problem to that divider. It sounds like your YIG is OK. Otherwise, you would have other errors. ("LO" unlock or too low or both) Hope that helps. I can make a better guess when I look at the CLIP files. Mark |
开云体育Hi Mark, ? Thanks for the reply and the thoughts. ? From the info in my CLIP, the 50 MHZ CAL signal is generated by dividing the 800 MHZ 2nd LO by 16.? The 2nd LO gets its power from the TEST MUX (U56).? This mux is dead – no enable signal, no activity on any of the control lines.? That’s where I’m stuck, I can’t figure out if it’s a hardware or software issue that is causing the 2nd LO to not get turned on.? The CLIP is not very clear on what tells the fractional divider (U55) to enable it. ? The 10MHz reference clock is the timing source for the 800 MHZ 2nd LO, and is present, both internally and at the 10MHZ output connector in the back. ? Thanks again, ? Mike ? ? From: <[email protected]> on behalf of "Mark Bielman via Groups.Io" <mbielman@...> ? Hi Mike, |
开云体育Did you make sure the cal signal was turned on?? You can turn it
off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams
wrote:
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开云体育Hi Tom,
I have verified that the 50 MHz ref is turned on in the input menu. ?I would expect that should turn it on, as would the automatic alignment process. ?If there is another setting somewhere that would turn it off, I am unaware of it,
and would welcome any pointers on how to turn it back on.
Cheers,
Mike
From: [email protected] <[email protected]> on behalf of Tom B via Groups.Io <tbryan@...>
Sent: Saturday, March 30, 2019 12:58:26 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal ?
Did you make sure the cal signal was turned on?? You can turn it off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams wrote:
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Mike, Can you see a 21.7Mhz IF signal on the cable plugged into A3J2?? I was looking over pages 55 - 75 of the ESA Service guide for a E4401B and there is a verification process to check on RF deck function.? I only suggest this because your original message stated your seeing signals but wasn't sure if they were as expected in Amplitude and correct frequency.?? Jon
On Saturday, March 30, 2019, 12:58:42 PM CDT, Tom B <tbryan@...> wrote:
Did you make sure the cal signal was turned on?? You can turn it
off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams
wrote:
Hi Mark, ? Thanks for the reply and the thoughts. ? From the info in my CLIP, the 50 MHZ CAL signal is generated by dividing the 800 MHZ 2nd LO by 16.? The 2nd LO gets its power from the TEST MUX (U56).? This mux is dead – no enable signal, no activity on any of the control lines.? That’s where I’m stuck, I can’t figure out if it’s a hardware or software issue that is causing the 2nd LO to not get turned on.? The CLIP is not very clear on what tells the fractional divider (U55) to enable it. ? The 10MHz reference clock is the timing source for the 800 MHZ 2nd LO, and is present, both internally and at the 10MHZ output connector in the back. ? Thanks again, ? Mike ? ? |
开云体育Hi Jon, ? Yes, I see an IF signal coming out of A8J3 when I follow the RF verification procedure when using an *external* 50 MHZ source.? The signal does very with attenuation, as describe in the service guide.? ? -- Mike ? ? From: <[email protected]> on behalf of "rpoz28cam via Groups.Io" <rpoz28cam@...> ? Mike, ? Can you see a 21.7Mhz IF signal on the cable plugged into A3J2?? I was looking over pages 55 - 75 of the ESA Service guide for a E4401B and there is a verification process to check on RF deck function.? I only suggest this because your original message stated your seeing signals but wasn't sure if they were as expected in Amplitude and correct frequency.?? ? Jon ? ? ? On Saturday, March 30, 2019, 12:58:42 PM CDT, Tom B <tbryan@...> wrote: ? ? Did you make sure the cal signal was turned on?? You can turn it off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams wrote:
Hi Mark, ? Thanks for the reply and the thoughts. ? From the info in my CLIP, the 50 MHZ CAL signal is generated by dividing the 800 MHZ 2nd LO by 16.? The 2nd LO gets its power from the TEST MUX (U56).? This mux is dead – no enable signal, no activity on any of the control lines.? That’s where I’m stuck, I can’t figure out if it’s a hardware or software issue that is causing the 2nd LO to not get turned on.? The CLIP is not very clear on what tells the fractional divider (U55) to enable it. ? The 10MHz reference clock is the timing source for the 800 MHZ 2nd LO, and is present, both internally and at the 10MHZ output connector in the back. ? Thanks again, ? Mike ? ? ? |
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Hmmm.. Ok.? -20dbm and 21.7Mhz.? Interesting case of trouble.? Controller / PLL power supplies in check?? Loops locked I guess, thinking what else to check.??
On Saturday, March 30, 2019, 1:13:21 PM CDT, Michael Williams <mike@...> wrote:
Hi Jon, ? Yes, I see an IF signal coming out of A8J3 when I follow the RF verification procedure when using an *external* 50 MHZ source.? The signal does very with attenuation, as describe in the service guide.? ? -- Mike ? ? From: <[email protected]> on behalf of "rpoz28cam via Groups.Io" <rpoz28cam@...> ? Mike, ? Can you see a 21.7Mhz IF signal on the cable plugged into A3J2?? I was looking over pages 55 - 75 of the ESA Service guide for a E4401B and there is a verification process to check on RF deck function.? I only suggest this because your original message stated your seeing signals but wasn't sure if they were as expected in Amplitude and correct frequency.?? ? Jon ? ? ? On Saturday, March 30, 2019, 12:58:42 PM CDT, Tom B <tbryan@...> wrote: ? ? Did you make sure the cal signal was turned on?? You can turn it off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams wrote:
Hi Mark, ? Thanks for the reply and the thoughts. ? From the info in my CLIP, the 50 MHZ CAL signal is generated by dividing the 800 MHZ 2nd LO by 16.? The 2nd LO gets its power from the TEST MUX (U56).? This mux is dead – no enable signal, no activity on any of the control lines.? That’s where I’m stuck, I can’t figure out if it’s a hardware or software issue that is causing the 2nd LO to not get turned on.? The CLIP is not very clear on what tells the fractional divider (U55) to enable it. ? The 10MHz reference clock is the timing source for the 800 MHZ 2nd LO, and is present, both internally and at the 10MHZ output connector in the back. ? Thanks again, ? Mike ? ? ? |
开云体育Yeah,?
This has me scratching my head. ?Power supplies on a8 look good.
Get
From: [email protected] <[email protected]> on behalf of rpoz28cam via Groups.Io <rpoz28cam@...>
Sent: Saturday, March 30, 2019 1:22:52 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal ?
Hmmm.. Ok.? -20dbm and 21.7Mhz.? Interesting case of trouble.? Controller / PLL power supplies in check?? Loops locked I guess, thinking what else to check.??
On Saturday, March 30, 2019, 1:13:21 PM CDT, Michael Williams <mike@...> wrote:
Hi Jon, ? Yes, I see an IF signal coming out of A8J3 when I follow the RF verification procedure when using an *external* 50 MHZ source.? The signal does very with attenuation, as describe in the service guide.? ? -- Mike ? ? From:
<[email protected]> on behalf of "rpoz28cam via Groups.Io" <rpoz28cam@...> ? Mike, ? Can you see a 21.7Mhz IF signal on the cable plugged into A3J2?? I was looking over pages 55 - 75 of the ESA Service guide for a E4401B and there is a verification process to check on RF deck function.? I only suggest this because your original message stated your seeing signals but wasn't sure if they were as expected in Amplitude and correct frequency.?? ? Jon ? ? ? On Saturday, March 30, 2019, 12:58:42 PM CDT, Tom B <tbryan@...> wrote: ? ? Did you make sure the cal signal was turned on?? You can turn it off on the E4401B. On 3/30/2019 1:39 PM, Michael Williams wrote: Hi Mark, ? Thanks for the reply and the thoughts. ? From the info in my CLIP, the 50 MHZ CAL signal is generated by dividing the 800 MHZ 2nd LO by 16.? The 2nd LO gets its power from the TEST MUX (U56).? This mux is dead – no enable signal, no activity on any of the control lines.? That’s where I’m stuck, I can’t figure out if it’s a hardware or software issue that is causing the 2nd LO to not get turned on.? The CLIP is not very clear on what tells the fractional divider (U55) to enable it. ? The 10MHz reference clock is the timing source for the 800 MHZ 2nd LO, and is present, both internally and at the 10MHZ output connector in the back. ? Thanks again, ? Mike ? ? ? |
开云体育Here's
how to turn it on from the menu Enable
the internal 50 MHz
amplitude reference signal as follows: (ESA E4401B and E4411B)Press Input/Output, Amptd Ref (On).
On 3/30/2019 2:26 PM, Michael Williams
wrote:
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开云体育Thanks Tom, ?
Yes, it is turned on.
Mike
Get
From: [email protected] <[email protected]> on behalf of Tom B via Groups.Io <tbryan@...>
Sent: Saturday, March 30, 2019 1:40:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal ?
Here's how to turn it on from the menu Enable the internal
50 MHz amplitude reference signal as follows: (ESA E4401B and E4411B)Press
Input/Output,
Amptd Ref (On).
On 3/30/2019 2:26 PM, Michael Williams wrote:
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开云体育I asked because I ran into this problem with my E4403B.? There
was no cal signal and it didn't not automatically turn on when
calibrating.? I found that I had to turn it on manually.? Tom
On 3/30/2019 2:42 PM, Michael Williams
wrote:
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开云体育It never hurts to double check such things. ?:-)
Get
From: [email protected] <[email protected]> on behalf of Michael Williams via Groups.Io <mike@...>
Sent: Saturday, March 30, 2019 1:42:02 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal ?
Thanks Tom, ?
Yes, it is turned on.
Mike
Get
From: [email protected] <[email protected]> on behalf of Tom B via Groups.Io <tbryan@...>
Sent: Saturday, March 30, 2019 1:40:15 PM To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal ?
Here's how to turn it on from the menu Enable the internal
50 MHz amplitude reference signal as follows: (ESA E4401B and E4411B)Press
Input/Output,
Amptd Ref (On).
On 3/30/2019 2:26 PM, Michael Williams wrote:
|