0000199: System temperature at L-band is way above what is expected

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Category

Severity

Reproducibility

Date Submitted

Last Update

0000199

[submission] front-end

major

always

14-12-09 11:14

04-01-11 14:53

Reporter

Gyula Jozsa

View Status

public

Assigned To

Hans van der Marel

Priority

normal

Resolution

fixed

Status

resolved

Summary

0000199: System temperature at L-band is way above what is expected

Description

The WSRT system temperature at L-band has increased in the period between the installation of the MFFEs to approximately the beginning of 2005. From 2005 on, the system temperature stays on average at a level of 36K, such that the process has reached a saturation. The nominal system temperature should be -30K.

From 2005 on a periodicity is superimposed on the Tsys curve. Roughly, a maximum in Tsys is reached in the first half of the year, a minimum in the second half. Independent fits to xtsys and ytsys of a simple sine function on top of a constant give a periodicity of 1 year and a maximum at the beginning of April (a minimum at the beginning of October) with an amplitude of 1.3 K.

The problem seems to affect all MFFEs.

Additional Information

The attached viewgraph shows the average system temperature from on.

Attached Files

WSRT_tsys_average.pdf [^] (24,559 bytes) 14-12-09 11:14

Relationships

Notes
(0000327) Hans van der Marel 04-01-11 14:53	It appeared that the high system temperature was caused by water in the radome material. To prevent birds from damaging the radomes the sides of the radomes were covered with polypropylene slabs. The glue with which they were fixed on the polystyrene of the radome did not make a water tight connection. So, during rainy weather water could creep between the two layers and during dry weather this slowly evaporated. Because there was water in the beam of the MFFE, the system temperature was affected. New radomes were installed, consisting of single layers of polystyrene. This lowered the system temperatures to normal values.

Issue History
Date Modified	Username	Field	Change
14-12-09 11:14	Gyula Jozsa	New Issue
14-12-09 11:14	Gyula Jozsa	File Added: WSRT_tsys_average.pdf
04-01-11 14:53	Hans van der Marel	Status	new => resolved
04-01-11 14:53	Hans van der Marel	Resolution	open => fixed
04-01-11 14:53	Hans van der Marel	Assigned To	=> Hans van der Marel
04-01-11 14:53	Hans van der Marel	Note Added: 0000327