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Re: Scoping the Power Rails [8566B]
--- Hi Jinxie, Could you put screenshot of the waveform in a photo folder, or attach to the posts if the image is not large? Also note how you are measuring (50-ohm terminated, with a scope probe
By Ozan · #123297 ·
Re: Scoping the Power Rails [8566B]
Probably the easiest way to explain it is that harmonic distortion makes every cycle look the same. Distorted, but the same. So the time between zero-crossings doesn't move around in that case. --
By Tom Lee · #123296 ·
Re: Scoping the Power Rails [8566B]
Yeah, it didn't sit quite right with me, either, distortion creating phase noise.? But I don't have the academic chops to explain it like you, Tom.? Thanks for weighing in.?Jim FordSent from my
By Jim Ford · #123295 ·
Re: Scoping the Power Rails [8566B]
@Ozan That is a very valid observation if indeed the wave is digitised further down the line. However, whilst that would certainly work fine as-is for digital purposes, is it realistic to suppose that
By Jinxie · #123294 ·
Re: Scoping the Power Rails [8566B]
You're right, Tom. Strictly speaking I believe it's random jitter of a pure sine that gives rise to phase noise. But I'm no expert in this area!
By Jinxie · #123293 ·
Re: Scoping the Power Rails [8566B]
Actually, not quite. Harmonic distortion does not generate phase noise (the integer relation of harmonics means that the zero-crossings do not undergo modulations). You need extra (and somewhat
By Tom Lee · #123292 ·
Re: Scoping the Power Rails [8566B]
------ First thing reference signal hits in the PLL (A7A1) is a comparator, followed by logic gates. It is fine if the reference is not sine-wave looking. It will be converted to a logic levels
By Ozan · #123291 ·
Re: 8341B Issues 1992 firmware
Luckily both sweepers still have the paper with the cal constants inside the unit so changing them will be easy
By Lothar baier <Lothar@...> · #123290 ·
Re: Scoping the Power Rails [8566B]
A thing to remember is that distortions in the 10MHz OUT could be related to the fact that the 100 MHz ref oscillator is not phase locked. Cheers! Bruce Quoting Jinxie <paul666@...>:
By Bruce · #123289 ·
Re: Scoping the Power Rails [8566B]
Thanks, Matt. I wouldn't have thought it would make enough difference either - BUT I guess any distortion of a pure sine wave generates phase noise which isn't exactly going to help, so who knows?
By Jinxie · #123288 ·
Re: Scoping the Power Rails [8566B]
That may actually be ok. The divided VCXO signal used to phase lock the VCXO to the reference may not need to be a good sine wave, though I'm not sure. If someone who understands the operation of this
By Matt Huszagh · #123287 ·
Re: 8341B Issues 1992 firmware
All you need to do to adapt the 40 CPU to the 41 is to change one of the cal constants so the top freq is 20 instead of 26.5 - I forget which one, but it is listed in the documentation Cheers! Bruce
By Bruce · #123286 ·
Re: 8341B Issues 1992 firmware
I aint getting this fancy in my old days:) the main purpose of this was to update the 8341B to work with the 8516A , i will just swap the CPU boards between the 40 and 41 that frees up the 40 as
By Lothar baier <Lothar@...> · #123285 ·
Re: 8341B Issues 1992 firmware
I believe there are signature analysis routines that could help debugging it. Cheers! Bruce Quoting Lothar baier <Lothar@...>:
By Bruce · #123284 ·
Re: A homemade diode power sensor for HP meters
Does anyone now how to contact Tobias Pluess? My email got bounced. Nothing to do with this issue. Tobias please email me off line. Peter
By peter bunge · #123283 ·
Re: Scoping the Power Rails [8566B]
Squeezed it in unseen. ;-) On RF OUT now it's showing 10.00000Mhz but the waveform on the scope (using 50 ohm 350Mhz analogue Tek scope this time) is not pure sine. The positive peaks are definitely
By Jinxie · #123282 ·
Re: HP8566B Spectrum Analyser Check-Lights ON
A though I had if anyone wishes to correct me or add to this, maybe there is a problem with the 5.2V regulator attempting to run to high where the crowbar is trying to prevent this thus loading the
By DW · #123281 ·
Re: 8341B Issues 1992 firmware
Fixing to do that ! I only paid $75 for the board and since the FW proms are ok I am almost tempted to keep it for the chips Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows
By Lothar baier <Lothar@...> · #123280 ·
Re: HP200CD oscillator
Part of the problem was that the cathode of a selenium rectifier was marked with a + sign to signify that it was the positive output of the rectifier system.? Of course that was the cathode.? So
By Bob Albert <bob91343@...> · #123279 ·
Re: 8341B Issues 1992 firmware
Hopefully you can return the CPU to the seller ! While you were at it, did you try the 8510/8516 using the CPU from the lab in your 8341??? Cheers! Bruce Quoting Lothar baier
By Bruce · #123278 ·
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