50 YEARS of PARKES RECEIVER INSTRUMENTATION

50 YEARS of PARKES RECEIVER INSTRUMENTATION.

M.W Sinclair and R.A.Batchelor 50 Years of Parkes Receiver Instrumentation. • Introduction In 50 years since the Parkes 64m was opened, radio astronomy receiver and processing technology has undergone a revolution. The quest for low noise, wideband reception has seen an evolution from room temperature crystal mixers and vacuum tube IF amplifiers via parametric amplifiers (cooled & ambient), transistor amplifiers, 4 Kelvin maser systems and cooled MESFET amplifiers to the GaAs and InP HEMT based amplifiers of the present day. This talk will attempt to trace that evolution.

THE EARLY RECEIVERS (1962 – 1965)

• Acceptance Testing – 75, 20 & 10 cm Crystal Mixers • Mk I H-line Receiver – Ex-Murraybank Multichannel • 20 cm Cooled Paramp Receiver • 11 cm Ambient Paramp Receiver • Extra Galactic H-line Paramp System 20 Cm degenerate Paramp (cooled). Acceptance Receivers Ts= 110K B= 20 Mhz. 75 Cm Crystal Mixer and IF Amp. 11cm Room Temp Paramp. 20 Cm Crystal Mixer and IF Amp Ts= 180K B= 100 Mhz The First Hydrogen Line Receivers

Extra Galactic H-Line Multi-channel H-line Front Upconverter into a 2.8 Ghz End. Degenerate parametric Crystal Mixer into an Amplifier. IF amplifier. Ts= 160K B= 100 Mhz Ts= 700K B= 2 Mhz 20 Cm Cooled Degenerate Parametric Amplifier Receiver System. PARAMETRIC AMPLIFIER SYSTEMS PT.1 Ambient Temperature Systems 21 cm H-line (Ts = 200K, B = 50Mhz) 18 cm OH-line (Ts = 150K, B = 30Mhz) ( 1612, 1665, 1667, 1720 11 cm Correlation Receiver (1967-1979) (Dual Channel Ts = 80K, B = 200Mhz) 21 cm H-line uMega paramp. ( Ts = 90K, B = 50 Mhz ) 18 cm OH-line dual channel, IF polarimeter, uMega Paramps tuneable 1612 to 1720 Mhz ( Ts =90K, B = 50 Mhz) PARAMETRIC AMPLIFIER SYSTEMS PT.2 Cryogenically Cooled (20K) Amplifier Systems.

NRAO 6 Cm Receiver ( Ts=100K, B=150 Mhz)

6 Cm RP/AIL Receiver ( Ts=50K, B=500 Mhz) In service from 1970 till 1984. Was repackaged in 1975 to improve noise performance. Single channel.

3.4 Cm Tony Kerr Receiver ( Ts=100K, B=50 Mhz)

THE EARLY SPECTROMETERS • Mk I Multichannel Filterbank – 48 Channels B = 33Khz • Mk II Multichannel Filterbank – 64 Channels B = 1, 10 & 100 Khz – 33 Khz later • Mk I Digital Correlator – 1024 Channels – 1 bit – 512 Channels – 2 bit – B = 10Mhz • Acousto-Optic Spectrograph – B = 100Mhz THE INTERFEROMETERS (64 METRE AND 18 METRE) • 1965 – 467/1402Mhz Continuously Variable Baseline – Used Crystal Mixer Receivers. First all transistor receiver system. • 1969 – 1421 Mhz H-line Interferometer – Used Micromega Ambient Paramps – Ts = 90K, B = 50 Mhz

HYBRID MODE FEED HORNS

Early receiver feeds were dipole arrays, rectangular and circ- ular waveguide or tapered choke ring apertures. Research by the Radiophysics Antenna Group resulted in the development of two types of corrugated feed horns– 1HE and 2HE

1HE horns – Wide band, circular beam, smaller size.

2HE Horns – Narrow band, more efficient, large.

Corrugated wideband 1HE horn section. TELESCOPE SURFACE IMPROVEMENT

Original Surface circa 1962. Current Surface ( 2011) Three iterations of perfor- Wire mesh outer surface. ated aluminium extensions. Steel plate 17 metre inner 37, 45 and 52 metre. surface. 17 metre inner surface adju- sted for mm wave work.

THE MOVE TO SHORTER WAVELENGTHS To take advantage of the reflector surface improvements, new receivers were developed for astronomically interesting bands at long mm wavelengths. 1.3 Cm Mixers at Ambient and LN2 temperatures.The cooled mixer utilised the 6 Cm cooled paramp as an IF amplifier. A 7mm and 3mm cryogenic front end for the Epping 4m tel- escope was used to evaluate the 17m inner mm surface.

22 Ghz (1.3 Cm) Maser 42 Ghz (0.7 Cm) Maser

Ts=80K B=250 Mhz

Ts=110K B=100 Mhz CRYOGENIC FIELD EFFECT TRANSISTOR AMPLIFIERS • 21cm Cooled MESFET Amplifier. – Ts = 50K, B = 200Mhz, dual channel. • Multifrequency Front End. – AT Prototype Mesfet Amplifiers • 20, 13, 6 & 3cm Amplifiers all in one Dewar • Ts = 40, 50, 60, 70K • B > 500Mhz (Better telescope scheduling) WIDEBAND H-OH RECEIVER (1993). 1.2 to 1.8 Ghz frequency coverage, cooled GaAs HEMT amplifiers and a cooled orthomode transition. OTHER GaAs HEMT AMPLIFIER RECEIVERS CONSTRUCTED 1990-2000 • 18 to 25 Ghz cooled HEMT Receiver. 2 pol. To replace maser.

• Project PHOENIX South’n Hem. TS Receiver. (1.2-3.0) Ghz

• 2.3 Ghz GALILEO Receiver. NASA/JPL Support. Ts=17.5 Kelvin

• 21 Cm Multibeam Receiver. 13 beam hex array. Avge Ts=23 K 21 CM H-LINE MULTIBEAM RECEIVER 1996 - ? 21 CM H-LINE MULTIBEAM RECEIVER. POST 2000 64m RECEIVER SYSTEMS

• 6Ghz METHANOL MULTI-BEAM RECEIVER.

• 10/50 CM (3 Ghz/600 Mhz) PULSAR RECEIVER.

• 15 – 25 Ghz (Ku/K Band) RECEIVER (With Compact Array InP HEMT LNA’s and an improved orthomode transition. THE END

Instrumental Improvement (1961 – 1988)

Receiver Figure-of-Merit

100

Tr Pamp Tcr Pamp 10 Tcr FET K maser rms noise fluctuations (mK)

1 Mar - 60 Sep-65 Mar - 71 Aug-76 Feb-82 Aug-87 Jan-93 Date

• Receiver noise temperature improvement at Parkes significant • Major improvements in bandwidth and stability • Bandwidth improvement reflected in FOM plot THE MASER ERA (1981 – 1995) • 22Ghz (K-Band) Maser – Ts = 80K – B = 250Mhz • 42Ghz (Q-Band) Maser – Ts = 110K – B = 100Mhz