A dream come true - seeing the
original Penzias
- Wilson radiometer:
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- a memo of my first, very memorable encounter with the Penzias -
Wilson radiometer at the Deutsche Museum in Munich, in
Finnish
- this fantastic piece of radio astonomy history has been arranged to
the museum by Dr. Arno Penzias, the horn still exists too in New
Jersey
- here is the block diagram of the radiometer, drawn based on the layout of the equipment at the museum
- an overall photo of the front-end microwave
arrangement (left to right: horn input, cold noise reference,
polariser/switch, hot reference, MASER amplifier, IF amplifier
- the back-end
rack containing power supplies, the IF amplifier and
envelope detector, the adjustable attenuation pad, the audio amplifier
and the paper plotter
- the feedhorn square-circular transition
and rotary joint (antenna pointing) and a closeup
photo
- the orthomode
transducer port for the cryogenically cooled reference waveguide
"cold" termination
- photo (bit out of focus) of the motor driven rotary
switch with ball bearing rotary waveguide joints and fine tuning matching screws
- motor driven rotary
vane, a different view
- the orthomode
transducer that feeds the receiver (right hand side), circular
wavguide section termination missing
- the 24 dB crossed waveguide coupler (note termination) at the front
lefthand side (the coupled to OMT via a short tapered section)
- the receiver port waveguide twist is at the extreme left and the
receive port waveguide bend,
between the Dewar and twist section, feeding the Ruby MASER
- the Argon tube hot noise source (note termination) at the left
rear and in this photo,
at the top rear (noise tube diagonally through waveguide wide side)
- the service
meter in front of the horn rotary joint and taper
- a photo without flash to show the cross
polarisation rejection attenuator vane (terminating adjustable
short missing)
- a photo with flash to show the waveguide
vanes (termination missing), showing the amplifier port fixed vane
in the front and the motorized rotary vane (switch) further down
- the MASER K
band pump source (a reflection Klystron ?) waveguide flange on top
of the Dewar, in front of the amplifier output N connector
- the MASER amplifier
output N connector and short coax section to another N connector
and coax to waveguide adapter for the mixer isolator (center right)
- the waveguide isolator
section (fed
at input and output via waveguide tapered sections) with the four valve
IF preamplifier mounted on top (slightly different view)
- the balanced Magic T mixer is at the left and the DC bias ports at
the extreme left (going to the diode mixer current meters)
- clearly there had been some local VHF interference breaking through
into the receiver IF at the mixer end - hence the ad hoc copper foil
shielding ;-)
- the Magic T balanced mixer Local Oscillator port for the Local
Oscillator (Reflex Klystron Oscillator ?) port is at the bottom left
(light blue waveguide/coax apapter)
- photo
of balanced mixer with adjustable shorts, bias box, LO waveguide
matching, LO coax to waveguide adapter (LO missing, possibly a Reflex
Klystron ?), also this
photo
- a view
of the cold reference source termination Dewar, showing also service
meter and Argon hot noise source
- the Magic T mixer diode
current indicators (these must have been most useful)
- the MASER DC magnetizing field controls were in the Dewar rack, on
the opposite side of the cryogenices control panel
- some of the cryogenic plumbing
- the molecular amplifier cryogenics
control panel, bearing the MASER type number M4901 and serial
number 1 (!)
- here you may find an illuminating (no pun intended) description of the Holmdel Horn
- link to the Nobel laureates of 1978 website
- and finally, here is a youtube video of the Holmdel Horn in action !
Created 11.11.2007
Published 19.12.2008
Updated 13.01.2019