Re: 10MHz reference input - can a square wave with 10MHz frequency be used?
Yes.
I'd put it through a low pass filter though. The 8920 input is sensitive enough. Here is one example:
looks like same design with stripline and SMD components.
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Re: Amtronix is the best. I'm amazed at their service.
?
Fully agree even though I have not used Ricks services for actual repairs or mods but only for advice as well as Rick's excellent posts here in the group.
I just wish we would have a similar workshop here in Sweden (or within Europe) that has the same experience and knowledge that Rick and his Amtronix has.
I am located in Sweden so shipping my 8920A back and forth to USA is just to expensive.
I would like to get my spectrum analyzer module calibrated and Agilent in Sweden would charge me 1400 USD to calibrate my 8920A (which would be a full calibration and not just the SA module).
It would also be nice to upgrade from 60W input module to the high power option 100W.
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10MHz reference input - can a square wave with 10MHz frequency be used?
I have a Spectracom GPS clock 8183A as my 10MHz frequence reference in my lab to my various instruments.
I am interested in testing the Leo Bodnar Electronics?Precision GPS Reference Clock:
However it seems that it only produces a square wave with 10MHz so my question is if the reference input on the HP 8920A accepts a square wave or does it only work with a 10MHz sine wave?
I have read through the user manual and on page 531 (in the version I have of the user manual) I find the paragraph "10 MHz REF INPUT" which does not state sinus wave only.
It just says:
=========
10 MHz REF INPUT??
Operating Considerations
Input frequency = 1, 2, 5, or 10 MHz
Input level >0.15 V rms
Input impedance approximately 50?.
When a valid signal is applied to the 10 MHz REF INPUT, the Test Set
automatically switches from internal to external reference.?
=========
However, under the paragraph?10 MHz REF OUTPUT it clearly states
"Waveform = sinewave"
So the question is if I can use a 10MHz square wave on the 10MHz ref input on the 8920A?
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HP8921A CRT filter glass needed.
Does anybody have the glass filter that goes in front of the CRT on an 8921 they would like to sell? Mine was cracked when i got it. I am going to do the LCD display mod and i thought this would be a good time to change the filter.
Dave
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Re: Bessel Function on HP8920A...
Chris,
Because you get the summary of messages and?because this Bessel thread?has consisted of several aspects,?it's not obvious what is new for you.? Is there something in particular you learned so far?
Hank
On Tuesday, August 1, 2023 at 06:16:28 PM EDT, zl1cvd wrote:
Awesome! Learnt something today..
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Re: Bessel Function on HP8920A...
Awesome! Learnt something today..
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Re: Bessel Function on HP8920A...
Correction:? that should be 2.0793 kHz (2079.3 Hz), not .20793 kHz.? Sorry about that.
Burt, K6OQK
On August 1, 2023 8:20:55 AM PDT, I? wrote:
As I mentioned earlier, if you use a modulating tone frequency of 0.20793 kHz (2079.3 Hz), the first null will occur at +/- 5 kHz of deviation for calibration or calibration confirmation.
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Re: Bessel Function on HP8920A...
Hank,
If you could give a step by step on how you accomplished this, it would be really appreciated, particularly how you were able to get the generator function to directly feed the receiver side without the need to use an external jumper.
As I mentioned earlier, if you use a modulating tone frequency of 0.20793 kHz (2079.3 Hz), the first null will occur at +/- 5 kHz of deviation for calibration or calibration confirmation.
Burt, K6OQK
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Re: Bessel Function on HP8920A...
Hank,
I got the attachment. That looks great.? I printed out the appropriate page and will give it a try as soon as I have some time in my shop.? Try it using a tone frequency of 2.0793 kHz.? The first null should give you 5 kHz deviation.
Thanks,
Burt, K6OQK
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Re: Bessel Function on HP8920A...
Keith,
The User Keys have to be programmed by you.
You only need one such key for this setup (Global K1, K2, or K3).? Knob spinning or direct numerical entry comprise the other button pushes you'll be using.
I would refer you to page 83 of this book available in our files section for the details.? Also, attached is an image from page 83.
? ? ? ? ? ? ? ? ? ? ? ? Agilent Technologies 8920A? ? ? ? ? ? ? ? ? ? ? ? ? RF Communications Test Set ? ? ? ? ? ? ? ? ? ? ? ? User¡¯s Guide
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Re: Bessel Function on HP8920A...
So what were the keys used.
Keith
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Re: Bessel Function on HP8920A...
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Re: Bessel Function on HP8920A...
After several hours of fumbling around with the HP's menus, I got a SA display of the built in SG output at 146.00 MHz.
At first I used a BNC jumper to get the SG into the SA, but then with more effort, got that coupling to happen internally.
The last hurdle was trying to adjust the deviation without having to switch between SA and SG screens which requires quite a few manipulations.? I? remembered vaguely something about User Keys and thinking maybe that might yield a way, with a few button pushes, to toggle between the two screens which would be fairly efficient.
With a LOT of time spent on menus and getting nowhere,? I couldn't find a way to toggle screens and was sure it couldn't be done.
The great surprise was there was a way to use a Global User Key to adjust the deviation WITHOUT even leaving the SA screen!? That's what you see above with the extra window at the upper left (red rectangle added) showing the adjustment for the deviation that is now visible and adjustable.? It? is set at 2.4k to null the carrier for a modulation frequency of 1.0k.
The orange ELD on the E6380 photographs well.? I reduced the orange intensity by a graphics program.? Use the separate attachment to view the image full size and peak sharpness.? The inline image inserted right in the email suffers from getting reduced to 640 pixels wide by the Groups.io system.
Hank?
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Thanks Robert,
Just let me know when if you find them.
Bill M.
On 30/07/2023 4:30 am, Robert G8RPI via
groups.io wrote:
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Sorry for the slow progress on looking for the boards. Not been
to the storage unit yet. I did find a box of boards from a 8923
but none of the ones you need in that collection.
Robert.
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Sorry for the slow progress on looking for the boards. Not been to the storage unit yet. I did find a box of boards from a 8923 but none of the ones you need in that collection.
Robert.
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Hi Rab,
I have recovered the 9821 to its former faults before the A10 PSU smoked,
I have discovered that my eprom blower has lots of bells and whistles, including the "Burn and leave unlocked".
I will revisit the copy of the working eprom from a known good board.
BTW, your advice that there was a bent pin was right on the money. Replaced Q3 on A9 and no more problems. (IRF-44 MOSFET)
MS _Diags gave all good voltages for the power system. RF all ok too except for the audio modulated tests AM SSB etc.
Very assuring to have a guru like yourself on these instruments.
?
Best regards
Bill M
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Re: Bessel Function on HP8920A...
you may have to have an external SA to do what you are asking on the 8920
Some service monitors ( like the IFR 1600 and COM-120 ) have a split screen where you can adjust the generator and view the output on the? SA portion of the screen.
The 8920 isn't structured like that.
The best you may be able to do is to setup the generate at one of the nulls and then switch to the SA ,,,,easy way would be to have both functions use the RF I/O port
Typically the 8920's are very close on modulation and output levels.but I usually use an 8902A to verify.
I do use the internal tracking gen function through a jumper to verify the internal alignment/calibration of the RF I/O assembly by making sure the frequency response across the entire 1Ghz is essentially flat.
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Re: Bessel Function on HP8920A...
I cant think of a way to do it via front panel. I'm pretty sure you'd have to flick between screens. Should be able to do it via HPIB/SCPI on the IEEE 488.2 port..
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Bessel Function on HP8920A...
Gang,
I want to do a Bessel Function confirmation of deviation calibration on my HP8920A using the internal RF generator and internal tone. Is there a way to adjust the deviation of the internal tone while watching the spectrum analyzer?
Burt, K6OQK
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Hi William,
?? Sorry to hear that. I wonder if one of the plug in boards bent
a connector on the motherboard and shorted it? Rick
On 7/27/2023 7:21 PM, William Macham
via groups.io wrote:
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Thanks Rab,
We are colleagues, not competitors.
I am still interested in your offer for boards, Robert has not
got to rummage through his Stash, so the pace has slowed.
I am going a bit backwards with the 8921, I was swapping boards
and the PSU smoked!!? No 5V, and the A9 board regulator was
hot.?
I'll pulls all boards once I get the Psu working, and measure
currents as I put them back in. It may be a foreign body fallen
in the works and shorting the 5V line, or some Capacitor failed.
I am still having Fun and have lots of patience.
"I struggle on Rewardless"
Bill M.
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Chris, ZL1CVD
Burt K6OQK
