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8662A output oddity

 

Hi, I recently acquired my first 8662A and while looking at its output on a spectrum analyzer I notice that there is a strange behavior that takes place in an approximate 2MHz span centered on 1024.8 MHz. At 1024.8 the noise floor increases by about 20dB and when tuning on either side of 1024.8 the noise floor decreases until it is completely back to normal at +/- 1 MHz on either side. I have included two pictures - one showing normal behavior and the other with the output tuned to 1024.8. This does not seem to happen at any other frequency in the unit's range. Has anyone else seen this? Thank you! 73, Jim N8ECI
morestainless
 

Congratulations on your fine acquisition.? I just got mine going.? Got some voltage and calibration adjustments to do?


On Sun, Mar 17, 2019 at 3:32 PM, hpagilent@...
<hpagilent@...> wrote:
Hi, I recently acquired my first 8662A and while looking at its output on a spectrum analyzer I notice that there is a strange behavior that takes place in an approximate 2MHz span centered on 1024.8 MHz. At 1024.8 the noise floor increases by about 20dB and when tuning on either side of 1024.8 the noise floor decreases until it is completely back to normal at +/- 1 MHz on either side. I have included two pictures - one showing normal behavior and the other with the output tuned to 1024.8. This does not seem to happen at any other frequency in the unit's range. Has anyone else seen this? Thank you! 73, Jim N8ECI

 

There is something wrong with the settings of the SA : VF is too narrow compared with the BW filter. Try with auto for all settings.
--------------------------------------------

On Sun, 3/17/19, morestainless via Groups.Io <lancelotburt@...> wrote:

Subject: Re: [HP-Agilent-Keysight-equipment] 8662A output oddity
To: "[email protected]" <[email protected]>
Date: Sunday, March 17, 2019, 11:41 PM

Congratulations on your
fine acquisition.? I just got mine going.? Got some
voltage and calibration adjustments to do?





On Sun, Mar 17, 2019 at 3:32 PM,
hpagilent@...<hpagilent@...>
wrote: Hi, I recently acquired my first 8662A
and while looking at its output on a spectrum analyzer I
notice that there is a strange behavior that takes place in
an approximate 2MHz span centered on 1024.8 MHz. At 1024.8
the noise floor increases by about 20dB and when tuning on
either side of 1024.8 the noise floor decreases until it is
completely back to normal at +/- 1 MHz on either side. I
have included two pictures - one showing normal behavior and
the other with the output tuned to 1024.8. This does not
seem to happen at any other frequency in the unit's
range. Has anyone else seen this? Thank you! 73, Jim
N8ECI
 

Hi, there should be a lit star in the upper right corner for settings which not give a calibrated display, right?
G?ran
 

On Mon, Mar 18, 2019 at 01:31 AM, jfphp wrote:
There is something wrong with the settings of the SA : VF is too narrow compared with the BW filter. Try with auto for all settings.
All settings on the SA were set to auto. This is the "full band" view of the 8569B for the 0.1-1.7GHz band.?

The problem is not with the SA, the problem I am asking about is in the 8662A: the 8662 generates tremendous broadband noise as it sweeps across 1024.8 MHz as shown in the pictures. At *all* other frequencies it generates a very pure tone as expected.

73, Jim N8ECI
 

Hi Jim
I have not seen anything like this on my 8663A (not exact same instrument, but very similar).
These generators has a are very modular build, with lots of cables between the boards. So it should be easy to find the source of the noise.?
Get the service manual, and follow the signal, by measuring the signal between each model in the signal path, until you find the bad module/board.

Had to do this to find what board generated spurs at certain temperatures in my generator.?

Br,
Askild


On Mon, 18 Mar 2019, 12:43 Jim Miller, <hpagilent@...> wrote:
On Mon, Mar 18, 2019 at 01:31 AM, jfphp wrote:
There is something wrong with the settings of the SA : VF is too narrow compared with the BW filter. Try with auto for all settings.
All settings on the SA were set to auto. This is the "full band" view of the 8569B for the 0.1-1.7GHz band.?

The problem is not with the SA, the problem I am asking about is in the 8662A: the 8662 generates tremendous broadband noise as it sweeps across 1024.8 MHz as shown in the pictures. At *all* other frequencies it generates a very pure tone as expected.

73, Jim N8ECI

 

?Jim,
The low band IF for the 8569B is at 2050MHz.? You may be seeing IF feedthrough due to the second harmonic of the 8662A.? It might be generated by the 8662A or by the mixer on the SA.??
--John Gord


On Mon, Mar 18, 2019 at 04:43 AM, Jim Miller wrote:
On Mon, Mar 18, 2019 at 01:31 AM, jfphp wrote:
There is something wrong with the settings of the SA : VF is too narrow compared with the BW filter. Try with auto for all settings.
All settings on the SA were set to auto. This is the "full band" view of the 8569B for the 0.1-1.7GHz band.?

The problem is not with the SA, the problem I am asking about is in the 8662A: the 8662 generates tremendous broadband noise as it sweeps across 1024.8 MHz as shown in the pictures. At *all* other frequencies it generates a very pure tone as expected.

73, Jim N8ECI
 

i second John's remark


On Mon, Mar 18, 2019 at 07:22 PM, johncharlesgord wrote:
?Jim,
The low band IF for the 8569B is at 2050MHz.? You may be seeing IF feedthrough due to the second harmonic of the 8662A.? It might be generated by the 8662A or by the mixer on the SA.??
--John Gord

On Mon, Mar 18, 2019 at 04:43 AM, Jim Miller wrote:
On Mon, Mar 18, 2019 at 01:31 AM, jfphp wrote:
There is something wrong with the settings of the SA : VF is too narrow compared with the BW filter. Try with auto for all settings.
All settings on the SA were set to auto. This is the "full band" view of the 8569B for the 0.1-1.7GHz band.?

The problem is not with the SA, the problem I am asking about is in the 8662A: the 8662 generates tremendous broadband noise as it sweeps across 1024.8 MHz as shown in the pictures. At *all* other frequencies it generates a very pure tone as expected.

73, Jim N8ECI

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