HP8563E SIMMCONN LABS NewScope-6 final adjustment procedure help please.

[djsb]

I'm in the final stages of adjusting my NewScope-6 VGA installation on my HP8563E spectrum analyser. The instructions are as follows

5 Adjustment
5.1 Zero-Span Fast Sweep Vertical Adjustment
The zero-span with sweep speed <30ms is digitized. The horizontal sweep of the digitizing system is
timed by a crystal oscillator and requires no adjustment. The vertical gain and offset need to be adjusted
in order to be consistent with the ADC in the 8560A/E.
5.1.1 Equipment Needed
Any RF signal generator that is capable of generating AM modulated signal up to 90% modulation depth,
with output carrier frequency within the frequency range of the spectrum analyzer, such as HP® 8656B.
The modulating signal needs to be between 400Hz and 1KHz. It can be any kind of repetitive signal, such
as sine wave or square wave. An external audio signal generator is needed if the RF signal generator
does not have internal modulation source.
5.1.2 Adjustment Procedure
Connect the output of the RF signal generator to the input of the spectrum analyzer. Set RF carrier
frequency to any frequency (100MHz for example), level to -10dBm, AM modulation depth to 90% and
audio frequency to 400Hz or 1KHz. Turn on the AM modulation and RF output.
Set the spectrum analyzer center frequency to the RF carrier frequency. Set frequency span to zero
span. Set sweep speed to 50ms, linear scale, video trigger. Set RBW and VBW high enough (>10KHz) to
not attenuate the modulating signal. Adjust reference level and trigger level for a stable modulation
waveform display. Adjust reference level such that the positive peak is within the top division of the
graticule, AND the negative peak is within the bottom division.
Adjust the Focus control on the second page of Display menu to the max value of 255. Two display lines
appear on the screen holding the positive and negative peak values of the waveform.
Press SWEEP button, set sweep speed to 20ms using the down arrow STEP button. The display lines
remain on the screen at the positive and negative peak values of the previous, 50ms sweep.
Adjust A2 R268 (VIDEO GAIN) and A2 R218 (VIDEO OFFSET) such that the display lines match with the
positive and negative peaks of the fast sweep waveform.
Adjust the Focus control away from the max value of 255. The display lines should disappear and the
adjustment is now complete.

Here is a brief email exchange

Hi David,
Please follow the operating manual regarding the adjustment procedure.  The manual says:

Adjust the reference level such that the positive peak is within the top division of the graticule, AND the negative peak is within the bottom division.

In your second picture, the negative peak is within the bottom division, but the positive peak is NOT within the top division of the graticule. Please adjust the reference level such that the required condition is met before proceeding.
There is no guidance regarding what video trigger value or reference level will result in a satisfactory waveform. The LCD assumes a spectrum analyser in good working condition. The adjustment goal is that the ADC on the NewScope-6 samples the signal with a consistent result as the ADC on the A2 processor board. So if your unit needs calibration which affects the ADC on the A2 processor board, the zero span fast sweep vertical adjustment needs to be redone after the calibration.

Regards,
Xu Wang
SIMMCONN LABS, LLC.
www.simmconnlabs.com

-----Original Message-----
From: David J S Briscoe
Sent: Monday, April 24, 2023 2:04 AM
To: Xu Wang <sales@simmconnlabs.com>
Subject: Re: Newscope6 Adjustment procedure-How critical is the RF signal generator amplitude?

Xu,
Thanks for your reply.
I have attached a couple of photos of my first attempt to do the adjustment. The first photo shows the 100MHz signal WITHOUT modulation (and the SA settings) and the second photo shows the screen after the setting of the trigger to video. I then changed the focus to 255 and pressed enter and got the 2 dotted lines. Is the amplitude of the sine wave shown correct, or should it fill more of the screen? Is the video trig level (223.6mv) what you would expect? I am unclear if what is on the screen is what SHOULD be on the screen, and what the next steps are?
For reference, the signal generator output is approx -9.3dBM (200mv Peak to Peak measured on my oscilloscope) and the modulation frequency is 400Hz. This spectrum analyser needs recalibrating, so there is probably some error in the amplitude measured on the screen. I appreciate any guidance you can give me in completing this adjustment (I've not touched
R268 or R218 yet). Thanks.

Thanks.

David

PS, This is the first time I've used this Spectrum Analyser, so I'm still learning the menu's etc. It had a non-functioning CRT when I bought it, so I've made SOME progress at least.

On 20/04/2023 22:40, Xu Wang wrote:
> Hi David,
> The adjustment tunes the gain and offset of the video signal going into the NewScope-6 board, such that the ADC on the NewScope-6 samples the signal with a consistent result as the ADC on the A2 processor board. It is similar to the fast sweep gain and offset adjustment in the 8560A/E service manual. The -10dBm signal doesn’t have to be very accurate, but should have a stable amplitude and AM modulation depth such that the demodulated signal does not drift much during the adjustment.
>
> Regards,
> Xu Wang
>
> Sent from my iPhone
>
>> On Apr 20, 2023, at 12:20 PM, David J S Briscoe wrote:
>>
>> Hi,
>> I'm finally getting around to doing the final adjustment procedure on my Newscope6 installation on my HP8563 spectrum analyser. How critical is the -10dBm amplitude level of the RF signal generator use to do this adjustment? What is the purpose of the adjustment procedure so that I can be clear on what I am doing? Thanks.
>>
>> Regards,
>>
>> David J S Briscoe

And

Top of the waveform between the first and second horizontal lines from the top of the screen; and bottom of the waveform between the first and second horizontal lines from the bottom of the screen. I.e. the waveform almost filled up the screen.

-Xu

On Tue, Apr 25, 2023 at 11:31 AM David Briscoe wrote:

    Xu,
    Thanks for your reply, Could you clarify the following for me?
    1/ When you mention graticule, I'm assuming you mean EACH SQUARE on the screen?
    2/ Or do you mean that the whole screen is the graticule and each square is what you call a division?
    3/ In my second picture, the negative peak is at the BOTTOM of the screen. Should I adjust the reference level so that the positive peak of the waveform is at the TOP of the screen (or NO LOWER than the first horizontal line from the top)? This would mean that the waveform would nearly fill the whole screen. Is this correct?
    Sorry for all the questions. Like I said before, I'm a newbie when it comes to spectrum analysers, but I'm eager to learn all I can. I'm also going to start a topic on the EEVBLOG forum asking for help as well. Thanks for your patience and assistance.

    Regards,

    David.

I have attached the 2 pictures of the screen on the HP8563E that I took during my first attempt at the adjustment. I'm wondering if anyone else has successfully done this adjustment procedure, and can you explain to me how I can change the reference level so that the modulating waveform (400Hz or 1KHz) fills the whole screen. I can post additional info from the service manual if needed, or take additional photos from a second and any subsequent attempts later. Thanks.