||Minerva Tropic Master W-117 WW2 Morale Receiver
by Duane Fischer, W8DBF
A Brief History and Technical Description
All of the sets I have been able to verify manufacturing dates on were made in
1945. The early version was exclusively made for the United States Army and
Navy as a morale receiver for entertainment use by the troops. It was released
to the general public in late June 1945.
The military set used a pair of 50L6 in a push/pull audio arrangement. The
civilian model used a pair of 25L6. What is interesting, is that the schematic
does not match the set. Certain modifications were made that do not show up on
the schematic. For example, one set I purchased from the original owner who
bought it in June 1945 in Hawaii, had the original schematic with it. The
schematic shows a pair of 25L6, but the set has a pair of 50L6 in it. All
appear to be the original tubes.
The tuning dial scale goes from 550 Kcs to 1600 Kcs and from 5.5 Mcs to 18
Mcs. However, the set with the 50L6 tunes from 540-1620 Kcs and 5.5 Mcs-18
Mcs. The set with the pair of 25L6 tunes from 550-1600 Kcs and from 5.5-19
It uses eight tubes; 25Z6 rectifier, (2) 25L6 or 50L6 audio output, (2) 6SK7,
6SA7 and 6SQ7. It does not have a power transformer and will run on either
AC/DC current. It has a powerful RF amplifier that improves sensitivity
greatly with the superheterodyne circuit. It has a 6 inch permanent magnet
speaker that is inadequate for the push/pull audio if a strong station is
It is built like a Tank and looks like it belongs in the military supply
depot. The cabinet is steel with heat ventilation louvers on both sides. Four
rear mounted thumb screws hold the chassis in the cabinet. The chassis slides
out the rear totally intact! There is a fold down solid steel tubular carrying
handle on the top. The front panel drops down to form a writing surface for
logs. A sliding steel door on the rear opens to reveal the power cord and
terminal strip with antenna and ground screws. The cabinet is treated to
survive all weather conditions and is extremely rugged. The paint is a
crinkle texture done in a light medium gray with a little blue blended in. The
lettering on the front door is a whitish cream color and is silk screened.
There is a very distinctive decal on the lower left. The manufacturer's
initials, MCA, (Minerva Corporation of America) , are in either red or gold.
The bus Bar Wiring provides solid anchorage and eliminates unnecessary
repair. The illuminated plastic dial face prevents deterioration. The speaker
is front firing and is mounted behind slots cut into the steel front panel.
There are only four controls; on/off/volume knob, variable tone knob, two
position band selector knob and tuning knob.
The cabinet measures 8 inches high, 14 inches wide and 8.5 inches deep. The
weight is 22 pounds.
It was prone to choke and output transformer failures primarily due to faulty
coupling capacitors and the resulting excessive current flow in the output
It was made by the Minerva Corporation of America located at 238 William St.,
New York, New York.
"Now, for the first time, you can purchase this remarkable radio
(for immediate delivery - no waiting) which was hitherto available
only for members of the Armed Services. The product of master
engineers, this radio had to be good to meet rigid government
specifications, and to present entertainment during the most adverse
climatic conditions. Sturdily designed to withstand rough treatment,
and expertly constructed to reproduce full, clear tones. The Tropic
Master is a radio that can't fail to satisfy the most particular
radio owner. The price is $75, Fed. tax included"
Taken from the original fact sheet included with the radio.
Tropic Master. Cabinet Restored by N0ALO.
The receiver shown in the photo is the military version dated June 19, 1945.
It was electrically rebuilt by KO6BB, Phil Atchley and refinished by N0ALO,
Lynn Brock. The decal reproduction was made by Keith Kupec.
There is a five part electrical restoration series in the 1995 Popular
Electronics issues from April, May, June, July and September. They were
written by Mark Ellis. If you need a copy, I have them.
I also have a copy of the original schematic and original data sheet. This
data sheet is the only one known to exist. It is the one that settled the
controversy as to whether or not the Minerva Tropic Master really was a morale
I first became aware of the existence of the Minerva Tropic Master in 1961. A
neighbor, a WW2 veteran who had been a radio man in the Philippines, loaned me
one. I did all of my short-wave listening and DXing on it. I used a 75 foot
long wire antenna made from Copper wire I removed from an old electromagnetic
speaker coil. I later built my own 31 meter center tapped dipole that hung
between my parents TV antenna on the roof of their home and a ten foot
Aluminum pipe I mounted on the garage roof. My father was not real thrilled
about the guy wires I nailed to the gypsum shingles! Fortunately for me, he
was a Carpenter and used some tar to keep the garage roof from leaking.
A dozen of the original QSL cards I received in 1961-1962 from short-wave
stations are shown on the HCI Short-Wave Monitor Achievement Certificate. I
enjoyed listening to those faint far off voices rising just above the crackle
of static forty-two years ago just as much as I do today. Provided the
receiver is my treasured Minerva Tropic Master WW2 morale receiver. After all,
the others are just radios!
This page last updated 27 May 2016