The panoramic spectrum display, invented by Marcel Wallace in the
1930's, provides a radio operator with a graphic display of radio
signal amplitudes at frequencies close to the signal to which his
radio is currently tuned. This allows the operator to observe
arrival of new signals, presence of interfering signals, or existence
of nearby spectral regions with more or less signal traffic. The
panoramic display is normally used as an accessory to a communications
receiver, thus the coined name "panadaptor". Wallace's company,
Panoramic Radio Corporation, of New York City, was the primary promoter
of panoramic radio displays during the 1930's and most of the
1940's. After the second world war, Panoramic Radio expanded its
line of spectrum analysis devices to find further applications in
radar, sonar and acoustics both as a laboratory tool and for
operational use. Panoramic later was acquired by Singer and
Singer in turn by Empire......and I have lost track of this evolution.
Many other firms built panoramic signal displays during the subsequent
cold war years. Spectrum analysis for panoramic display is now
performed digitally as part of the signal processing in some modern
(costly) receivers. This website is focused on the beginnings of
panoramic radio displays.
Panoramic SA-1 and SB-1 Radio Spectrographs
An early panadapter
featuring a 5 inch CRT was pictured in QST for March 1942, page
16, but not identified. It is now known to be a Panoramic model
SA-1. The author has aquired a Panoramic SB-1, Type T200
which is a utility spectrum analyzer version of the SA-1, incorporating
an untuned mixer input stage for use with an external heterodye
oscillator. An SA-1 Type T200 unit, being
restored by a collector in the UK, is shown below, with the author's
SB-1 on the right. Both units are identified as "Panoramic Radio
Spectroscope" on the front panel. The SB-1 unit also bears the
name "Panoramoscope" on its rear panel identification tag. The names
"Panoramic Adaptor", and "Panalyzor" were apparently not
used until later (SA-3, SB-3) units in the 1943-44 era. A photo
showing a similar unit also
appears in "The Secret Wireless War" by Geoffrey Pidgeon, page 99.
This SB-1 analyzer was apparently
built during the third quarter of 1942, as indicated by date codes on
most of its RCA metal, octal-based tubes. The SB-1 has an
enameled metal horizontal scale mounted in front of the CRT,
while the SA-1 is equipped with a green plastic graticule against the
CRT screen (similar to the graticule on later model SA-3 equipment),
suggesting later manufacture.
SA-2A Radio Spectrograph
analyzers were as large (17"w x 9"h x 13" d) and heavy (
lbs) as many radio receivers. The model SA-2 version of the Radio
Spectrograph was apparently intended to be smaller, as an accessory to
a radio, rather than a competitor for bench space. Photographs of
smaller (unidentified) units appeared in QST for March and July, 1942
. A Panoramic model SA-2A Radio Spectroscope has been
found. This unit is very similar to the unit described in QST,
July 1942, but has its two-inch CRT mounted in a separate "doghouse"
connected to the main unit by a multi-conductor shielded cable.
This two-piece unit, is apparently a commercial model, produced
for the Navy at
the outbreak of the war. The only indication of Navy purchase is
the US and Anchor engraved on upper right corner of the nameplate.
Production date of this unit is estimated as the second half of
1942. Tubes in the unit bear May-June 1942 date codes. The
stamped on the plate - 2,273,914 and 2,279,151 - were awarded on
February 4 and April 7, 1942. The next panoramic reception patent
awarded to Marcel Wallace and Panoramic radio was number
2,312,203, awarded February 23, 1943. It seems reasonable to
infer that if this unit had been manufactured after February
1943, their latest patent would have been cited on the nameplate.
The commercial heritage of the SA2A is further demonstrated by the
component layout and the commercial components, such as waxed paper
capacitors. Not visible, in this picture, are the capacitors hidden
terminal board and inaccessible without major disassembly. This is not
an easy unit to repair.
Panoramic SA-3 Panoramoscope
The later model analyzer, incorporating a 3 inch CRT, a
spacious chassis, and mil-spec style components and component layout
was the model SA-3, initially called a
"Panoramoscope". Note the
difference in layout and wiring.
The commercial side of the SA-3 family included five models (as of
1945), with more added during the next 20 years. Models were
distinguished by Type numbers indicating
maximum sweepwidth and sometimes suffixes to denote different input IF
frequencies within a Type.
Input IF Frequency
450 - 480 kc.
450 - 480
450 - 480
kc. or 21.4Mc
Mc, 10.2Mc, 10.7Mc, or 21.4MC
21.4 or 30
21.4 Mc or 30
(Note: in the
ancient era of panadaptors, MHz and kHz had not been invented yet, and
frequencies were measured in Mc and kc.)
Contemporary receivers with IF in the 450 - 480 kc range included the
Hallicrafters SX-28, the Hammarlund Super PRO, and the National
HRO plus many other receivers. These receivers also
existed, either unchanged or repackaged, under multiple military
nomenclatures. The Hallicrafters S-27 and S-36 VHF receivers used
a 5.25 Mc. IF. The General Radio P540 UHF/microwave
receiver (better known as AN/APR-4) used a 30 MHz IF. Nems
Clarke receivers, built during the 1950's, used 21.4 Mc
IF. A later panadaptor model, the SA-8 Type T-100, could be
ordered with 500 Kc IF for use with the 1950's era Collins receivers.
Many military versions of the model SA-3 appeared, starting in
1943. These units were apparently the first to be called
"Panoramic Adaptor". Shortening of this name to "Panadaptor" is
probably attributable to the military operators and technicians using
them. A Navy technical manual for the model RBY was released June
30,1943 and an Army technical manual, TM11-446 for the BC-1031 and
of the SA-3 family, was released July 30, 1943.
versions of the SA-3 family include:
An apparently later evolution of the SA-3 family, was the SB-3
"Panalyzer" shown below. A Panalyzer added an untuned mixer stage
to allow use of an external oscillator to translate input signals to
the input center frequency of the panadaptor which followed.
Panoramic PCA-2 / Hallicrafters SP-44
After the end of WWII,
with loss of military orders and shrinking staff, Panoramic attempted
to sell radio amateurs on the virtues of their product. They
produced Model PCA-2, with a 2 inch CRT and electrically very similar
to the 1942 model SA-2A. A similar model was made under
contract for Hallicrafters who marketed it as the Hallicrafters
SP-44. Internally, the component layout and parts quality of
these units regressed from the mil-spec quality of the SA-3 units above
to more closely resemble the SA-2A. There are at least three
different schematics from this family of panadaptors, with minor
in the power supply circuits and in the biasing of the reactance tube
S-35 Panoramic Receiver
This panoramic receiver,
consisting of a Hallicrafters SX-28 receiver in a common cabinet with a
panadaptor distinguished by a 5 inch CRT, was shown in Hallicrafters
pages in the 1945 Radio's Master catalog and other Hallicrafters
advertising of the period. The front panel of this panadaptor
does not resemble any of the contemporary
Panoramic models, although the tube lineupand circuitry is
suggestively similar to
that of the SA-1/SB-1 units. (This comment on circuitry based on a
schematic published in Radio News Magazine, March 1945).
The author has not yet found anyone who owns or has even seen a
Hallicrafters S-35 or a manual for one. Possibly the S-35 was a
prototype, built in unsuccessful competition with Panoramic for a
military contract. This possibility is suggested by comparison
with the Navy Type RBY-1,. built by Panoramic and sharing its cabinet
NAVY RBY-1 , by
Panoramic with SX-28
About this webpage.
webpage is a result of an information search that began when the author
purchased the SA-2A panadaptor shown above. Neither the author or
the seller realized the age of the unit or the sparcity of available
information. Over a period of 18 months, much panadaptor
information has been found, through the generous assistance of many
hams, collectors and librarians. Some misinformation has also
been encountered, offered in the belief that it was true. In the
course of returning the SA-2A to operation, the author has done
enough reverse engineering to create a pseudo-manual for the
unit, but a copy of the manufacturers manual has never been
found. This webpage is an offering of some of the panadaptor
history that was found during the search.
The author wishes to thank the many people who have contributed
information to his search, including:
King County Library
Oberlin College Library
University of Washington Library
and offers appologies to any who I have omitted.
----------More to come -----------------
This webpage is a work in progress. Comments, corrections, and
added information are welcomed.
Thanks for your visit.
Chuck McGregor, N7RHU email address current at QRZ.com