lband wide calibration
nov,2002
The lband wide receiver covers 1120 to 1730
Mhz.
It is a native linear receiver with an optional hybrid than can form
circular
polarizations (located outside of the dewar).
history
recent
system performance measurements
Daily
monitoring of Tsys
Dewar
temperatures
gain curves
lband wide measurements by date
cal values
rfi measurements
History (top)
- 26sep08: lbw
cals remeasured.
- 05sep08: lbw warmed up looking for cause of interference. bias
voltagel bulkhead cable replaced.
- 29aug08: lbw cals
remeasured before warmup.
- 08jun08: lbw cryo problems.
- 08apr08: lbw cal box brought to lab, cables tightened. (need to
remeasure cals).
- 02apr07: finally installed the lbw cal
values that were measured back on 22apr07.
- 06feb07: tuned the bias on the 2nd/3rd stages of the dewar amp to
equalize the gain in polA,polB
- 18dec07: found that polB had
a 25% higher Tsys than polA.
- 22mar07: Lbw brought down to lab. Put back on telescope 03apr07.
Dewar
openned up and the bolts in omt were all tightened (they were loose).
Trcvr was measured on the test range. The polA resonance at 1400
Mhz (there since the jun05 dewar warmup) is not gone. The wider polB
resonance around 1395 is stil present.
- 27oct06: upstairs
iflo cable test shows loose cable in 750 mixer chassis.
- 16jun06: dewar warmed up and openned. found loose sma feed thru
for
polB
cal. fixed. was probably causing the drifts in Tsys for polB.
- 23feb06: lbw cal
value remeasured.
- 04dec05:
lbw polB cal value jumps by 20%.
- 24nov05: lbw polB filter 3 (1230-1470) shows jumps in total
power. This
has been happening since at least last jun05 (maybe earlier).
- 23nov05: new diodes installed lbw. cal
values remeasured.
- 21jul05: diode 1 lbw died. changed software to always use diode
2. This
will affect polarization measurements since diode 2 introduces a
90 deg phase shift between polA, polB outputs.
- 10jun05: remeasured
the cal values after cables repaired.
- 01jun05: dewar warmed up and some cables repaired. Caused resonance
in polA and polB near 1400 Mhz.
- 16may05: Tsys for lbw started jumping. (more
info).
- 06aug04: cals
remeasured to correct for the jump that occurred on 23apr04.
- 23apr04: Tsys polB jumped by up to 20 %. Then wandered around
about for
about a month. The jump was from the cal or cal cables (not the actual
Tsys). see polB
cal jumps
- 17feb03 New lband wide receiver installed.
- 22nov02 lband wide horn moved down 3.67" to put phase center in
the
correct
position.
- 26aug02 lbn horn moved down 3.84" to put phase center in the
correct
location.
Gain curves: (top)
02nov03:
lbw gain curves from mar03 thru oct03 (gain curves)
17feb03: new lband wide receiver installed.
lband
wide gain curves after horn focus moved (data 21nov02 thru 31dec02).
(gain curves)
gain, tsys
calibration lbw (sep01). (gain curves.)
fit
to gain(az,za) and comparison of pitch, roll, focus loss to measured
losses
(aug00). (gain curves.)
Lband wide measurements
by date: (top)
26sep08:
lbw cals remeasured.
29aug08:bw
cals remeasured before warmup
02jul08: lbw cooldowns, omt stage not
getting below 180K
22apr08: pol B is noisier than polA.
08apr08: lbw cal box brought
to lab and components swept on network analyzer (.pdf)
02apr08:
cal values measured on 21apr07 finally installed.
2007
18dec07: sefd shows polB
Tsys
25% greater than polA.
21apr07:
polA resonance at 1400 Mhz gone after omt bolts tightened. PolB at 1395
still present.
19feb07:
lbw beam maps of 3C138.
13feb07:
sefd around 1100 Mhz and some rfi plots.
30oct06
cable test lbw in upstairs iflo shows loose cable in 750 mixer chassis.
09mar06:
cycle through the 9 rf filters checking Tsys variations
07mar06:
lbw calPolB. tapping the cables external to dewar to not change
caldeflection.
07mar06:
1230-1470Mhz filter. See if Tsys stable when in, out.
07mar06:
jun05 warmup/cooldown caused resonance in polA and polB.
2006
26dec05:
no power in polB for 2 hours (probably and iflo problem).04dec05:
lbw cal value polB jumps by 20%.
28nov05:
cal values for new diodes installed.
26nov05:
lbw polB filter 3 shows jumps (1230-1470 Mhz)
28oct05:
lbw calibration jumps for murray's OH data.
05sep05:
lbw receiver status jun05-sep05. 1400Mhz resonance and diode 1 dies.
23jun05:
resonance in lbw polA at 1400 Mhz.
21jun05:
installed new cal values after polB cal cable fixed.
03jun05:
time for lbw dewar to cool down.
16may05:
power jumps, 1.2 hz gain variation from crosshead. Something loose in
dewar.
2005
02aug04:
ripples in lbw around 1390,1400 Mhz. seen a1861(may04),
a1914(aug04)
23apr04:
polB cal jumps.
09apr04:
system
performance after kevlar cables tensioned and tertiary moved.
2004
02nov03:
lbw gain curves from mar03 thru oct03 (gain curves)
11jul03:
compare lbw horns: kildal and german cortes.
9apr03:IFLO
compression by the FAA 1350/1330 radars using lbw,lbn (29apr03).
17apr03:
LBW SEFD vs frequency using 3C138.
17apr03:
resonances in the new lbw receiver.
03mar03 first
look newlbw performance.
Tsys,
Trcvr, and scattered radiation from hilltop measurements.
17feb03 new lband wide receiver installed
2003
lband
wide gain curves after horn focus moved (data 21nov02 thru 31dec02).
(gain curves)
lbw
system performance after horn focus move (21nov02 thru 31dec02).
lbw
gain increase after horn moved to correct phase center (22nov02)
100
sec oscillation in polB total power (2001,2002)
Compare
sefd 01sep01 thru 01may02 lbw,lbn using new cal values (may02)
resonances
in the lband wide OMT (mar02)
2002
gain,
tsys calibration lbw (sep01). (gain curves.)
problems
using the lbw system in circular mode (hybrid in) jul01.
2001
fit
to gain(az,za) and comparison of pitch, roll, focus loss to measured
losses
(aug00). (gain curves.)
lband
Sefd, tsys, and gain (night) aug00 (html)
(position switching on flux calibrators using the
correlator).
Compare Sefd,
gain, Tsys at multiple lbw frequencies (14jul00 daytime)
Compare lbw and lbn receivers (Sefd,
gain, and tsys 12jul00 daytime).
Lbw measurements by
topic:
(top)
Resonances:
Cal jumps:
Rf filterbank
The hybrid:
Compression:
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