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

Mcs.

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

tuned in!

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

tubes.

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

receiver.

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