early Comet, with it's
Hammarlund supplied electro-dynamic speaker. It's
eight-tube superhet with on-board AC power supply. The radio
545KHz to 20MHz using five sets of plug-in coils. The
capacitors, plug-in ceramic coil forms, and double tuned IF
transformers were all Hammarlund products.
are two 465KHz IF stages
with a total of six tuned circuits. The middle knob and drum
are the main tuning control. The two controls to the right
left provide "vernier" tuning of the mixer and local
The toggle switch actuates a fixed-tuned BFO for CW
List price was $130, less tubes and cabinet.
initial Comet "Pro" appears
in Hammarlund's ad in April 1932 QST. "An eight-tube
super-heterodyne which will do all that the professional operator
demands between 14 and 200 meters." The center control with
illuminated drum dial is now band-spread, while the two knobs with
circular scales are "band-set" (main tuning). The type 47
audio-output power pentode has been eliminated in favor of a type 27
triode, and a phone jack has been added to the front panel.
NYC Radio Row retailer Leeds offered the Comet Pro for an introductory price of $88.20 while mentioning a $150 list price.
early 1930's were a period of extremely rapid development of shortwave
receivers. The Comet Pro underwent a series of changes
it's life time. The schematic for the first major revision is
dated September 1932. The calibrated band-set dials have been
recessed behind the panel, and are now actuated by friction-type
reduction drives acting on the edge of the dials. Later
"Pro's" were housed
in a wrinkle-finished steel case. The crystal
is shown at the right.
handle has been incorporated into the BFO coil (lower left) to allow
operator adjustment. The
plug-in coils are
covered by cylindrical
shields to limit unwanted coupling. New
IF transformers, tuned by air-dielectric trimmers to acheive better
stability, were introduced in late 1932.
claims and counter
claims expounded in period advertising often make interesting
reading. For example, in October 1933 QST, McMurdo Silver
that Admiral Byrd has chosen his 5A receiver for his next Antarctic
expedition. Two months later Hammarlund published a
radiogram from an Arctic expedition complete with pictures of a walrus
and an Eskimo.
Comet Pro enjoyed considerable success in the commercial
Here's a DC Comet Pro, one of several, modified by AT&T for use
frequency-selective voltmeters to service multiplex telephone
circuits. The added meters read signal level in dB and
voltage. Custom coils tuned the LF band. (N3FRQ
Eastern Air Transport
Transcontinental & Western Air,Inc.
Inter-American Aero Travel and Supplies
44th Division Aviation,N.J.
War Department, Air Corp., Wright Field
Columbia Broadcasting System
Icelandic State Broadcasting Service, Reykjarik, Iceland
Short Wave Station VE9GW, Canada
Station CMKA, Cuba
American Radio News Service
U. S. Embassy Santiago, Chile
Argentine Embassy, Paris, France
DOMESTIC COMMERCIAL SERVICE
Georgia Agricultural Dept.
Police Dept., Youngstown, O.
Police Dept., Klamath Falls, Ore.
Albany Junior Chamber or Commerce
Mississippi State Penitentiary
Hotel New Yorker
Naval Research Labs., Washington
U. S. S. Woodcock
Radio Material School, Washington
9th Naval District
U. S. Navy Yard, Charleston, S.C.
Marine Corp., Signal Section
Message Center, Washington
Headquarters, 8th Corp Area, Fort Sam Houston
Signal Section, San Frdncisco
Signal Section, Honolulu, T. H.
Signal Section, Manila, P. I.
Signal Section, Corozal, C. Z.
Headquarters, 4th Corp Area, Fort McPherson
Headquarters, 9th Corp Area
FOREIGN GOVERNMENT SERVICE
Department of National Defense, Canada
Director of Signals, Canada
Director of Naval Stores
Royal Administration of Telegraph, Stockholm
Radio Nautica, Italy
First Brigade Exchange, Haiti
FOREIGN COMMERCIAL SERVICE
Radio Electric, Switzerland
Technish Bureau, Kolomen, Hoiland
Rothermel Corp, Belgium
Eltone Ceritte, Italy
Muvaffak Bey, Ankarg, Turkey
Standard Oil Co. of Venezuela
Harry Pegram, South Africa
W. F. Greene, Dutch West Indies
Pedro Perez, Saintz, Spain
Post Exchange, Canal Zone
PROMINENT AMATEURS IN ALL DISTRICTS