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Cryogenic PAF Development

Cryogenic PAF Development. Progress Report. PAF Workshop May 3-5, 2010 Provo, UT Roger Norrod. Cryogenic PAF. BYU/NRAO targeting noise and efficiency competitive with best single-beam receivers. i.e. 18K, 70% at L-band.

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Cryogenic PAF Development

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  1. Cryogenic PAF Development Progress Report • PAF Workshop May 3-5, 2010 • Provo, UT Roger Norrod

  2. Cryogenic PAF • BYU/NRAO targeting noise and efficiency competitive with best single-beam receivers. i.e. 18K, 70% at L-band. • At Green Bank, construction of cryostat for 19 element L-band PAF underway. PAF Workshop Provo, UT May 2010

  3. PAF Cryostat With blank-off covers for leak check April 27 Model Drawing 24 X 21 X 8 in. 61 X 53 X 20 cm. PAF Workshop Provo, UT May 3-5 2010

  4. Dual LNA and Thermal Transition NXP SiGe transistors. Surface mount components. Thin-wall SS tubular coax. Quartz beads for vacuum seal and center conductor heat sink. Est. input coax heat load 150 mW / chan. Bias power 17 mW / chan. 14 of 20 assembled, 8 tested cold. Pair of two-channel LNAs with integrated low-loss coaxial lines for transition from 15 to 300K, vacuum seal, and antenna base interface. LNA based on: S. Weinreb, J. Bardin, H. Mani, G. Jones, “Matched wideband low-noise amplifiers for radio astronomy”, Rev. of Sci. Instr., vol. 80, 044702, 2009. PAF Workshop Provo, UT May 3-5, 2010

  5. LNA Measured Performance Noise Y-factor measured with LN2 cold load at room temperature SMA connector. PAF Workshop Provo, UT May 3-5, 2010

  6. LNA Measured Performance PAF Workshop Provo, UT May 3-5, 2010

  7. LNA Measured Performance PAF Workshop Provo, UT May 3-5, 2010

  8. Dipole Ohmic Losses Sky noise tests Nov-Dec 2009 to determine dipole noise contribution. Measured on Ciao room-temp amps (~35K). PAF Workshop Provo, UT May 3-5, 2010

  9. Dipole Ohmic Losses • Measured LNA/Rx with coaxial hot/cold load. • Attached dipole and measured using ambient load and sky. • Corrected for scatter, galactic plane, etc. (Tsky = 7.5K) PAF Workshop Provo, UT May 3-5, 2010

  10. Achievable Tsys? Total 22 K PAF Workshop Provo, UT May 3-5, 2010

  11. Next • Install LNA/TT assemblies. • Cooldown, measure cooling capacity. • Mount in FEB. • Sky noise tests. • Antenna (20m) tests. PAF Workshop Provo, UT May 3-5, 2010

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