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anritsu mg3692c synthesizer

anritsu mg3692c synthesizer

12jun15

09jun15: rfi measured in screen room
12jun15: rfi measures in turret room. opening closing lo cabinet doors with anritsu on,off

The anritsu mg3692c is a 10MHz to 20Ghz synthesizer that was purchased to replace the hp83712 20GHz synthesizer used as the upstairs first lo.

09jun14 anrit3692c in screen room

We measured the rfi from the anritsu mg3692c synthesizer on 09jun12 in the screen room.

The setup was:

anritsu spectrum analyzer using the standard screen room automated script:

span 100 MHz, rbw 30KHz, avg 10 sweeps, preamp on, cover 100 to 3000 MHz
record avg, maxhold, minhold
scan from 100 MHz to 3000 MHz

Before starting we found open spots at the corners of the case. We used aluminum tape to cover this. It improved things by about 10db

You can see the tape in the probe location images

We did measurements at 3 locations:

left side middle of seam on top. One set with Bfield and 1 set with Efield probe
touching the lcd display (with Efield probe)
6" in front of lcd display (with Efield probe)

The Data scans:

The plots for each dataset have 2 pages

page 1: 100 to 3000 ghz in 3 frames. black in the average, red is the peak hold
page 2: blowups of peak hold spectra around: 327 rcvr, lbw Low, lbwHigh
page 3: shows the period of the combs. It as abs(fft(spc)) .

the spectra on page 2 show a 2.5 MHz probe. the transform of the spectra shows peaks at multiples of .4 usec (1/2.5 mhz)

901b (H field probe) along the side of the analyzer (.ps) (.pdf)

probe location (.jpeg)

904b (Efield probe) at the same spot as the 901b probe. (.ps) (.pdf)

probe location (.jpeg)

904B (Efield probe) touching the lcd screen in front. (.ps) (.pdf)

probe location (.jpeg)

904B (Efield probe) 6 inches in front of the lcd screen (.ps) (.pdf)

probe location (.jpeg)

Summary:

The E field probe shows continuous junk to about 350 MHz
The edge measurements have a peak at 320MHz:-90dbm, 325 MHz -88dbm.
The lcd has a 2.5 MHz comb that goes up to lband (when Eprobe is touching the lcd screen).

touching screen

337.5 MHz -85dbm

6 inches from screen:

332.5 mhz -97 dbm

processing: x101/rfi/miscdevice/mg3692c/do_scrnroom.pro

150612: measure rfi in dome from anritsu.open close lo cabinet

We installed the anritsu mg3692c synthesizer in the lo racks in the dome on 12jun15. It was going to be used as the first LO.
The rfi from the anritsu was measured in the screen room (see above). We needed to know if the if/lo shielded cabinets gave enough isolation to not bother regular observations with the anritsu emissions.

SETUP:
To test this our setup was:

install anrisu in shielded racks in the upstairs if/lo
use the 327 rcvr to measure the rfi from the anritsu
use hp2 (hp83712) as the first lo for the 327 rcvr.
Take data with the mock spectrometers:

8192 channels, 160 MHz bw, 1 second dumps.

While data was being taken, the following operations were performed:

start with shielded door closed, anritsu on
open door
turn off anritsu
close door,
open door
turn anritsu on
Then repeat the above cycle.

The results:
the first image is a dynamic spectra of 480 seconds of data (.gif)

i skipped the first 150 secs of data since some sources were passing through the beam.
The horizontal axis covers 322.5 to 332.8 MHz. the vertical scale is 150 to 482 seconds.
horizontal colored lines show when things occurred:

D_Close: close the cabinet door. Anritsu is on
D_Open : open the cabinet door, Anritsu is on
D_Close: close the cabinet door. Anritsu is off
D_Open : open the cabinet door, Anritsu is off

some of the birdies:

the large birdie at 327 is the dc bump from the mock spectrometers.
You can see that a large number of birdies go away when the door is closed.
The birdies that don't change strength when the door is closed are not coming from inside the cabinet.
You can see birdies from the anritsu around:

322.5, 325, 327.5,332.5 MHz .. looks like a 2.5 MHz comb.

The 2nd set of plots shows the spectral strength (.ps) (.pdf)

Page one: covers 322.4 to 333.4 MHz

The colored traces are:
door open:

anritsu off
anritsu on
door closed
anritsu off
anritsu on

The blue vertical lines show the 2.5 MHz comb from the anritsu.

Page two: is a blowup around 327.5 MHz

each element of the 2.5 mhz comb has sidelobes at 20KHz

Page 3 replots the screen room data of the anritsu rfi.

top: 100 MHz to 3000 Ghz.
middle: 300 to 350 MHz. (black is peak hold, ,red is avg 20 spectra)
bottom: abs(fft(spc)) shows the period of the combs.

.4 usecs is 2.5 mhz spacing

Summary:

We see a 2.5 MHz comb (with 20kHz sidelobes) coming from the lcd screen of the anritsu
In 20 second average, 20 KHz rbw, we don't see them with the if/lo cabinet closed
The plots also show the isolation of the if/lo cabinet door. There is nothing obvious getting through at 327.

processing: x101/150612/rfianrit.pro
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