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Though this little radio set was only
adopted as an expedient, it saw significant service in WW-II even after
it's successor, the SCR-284, became available. Most notably with Filipino
Guerrilla forces, the China/Burma theater, and in the North African, &
Italian campaigns, not to mention with various Allied countries (who all
favoured it's small size & extremely simple operation). Do to this
small size and weight (71lbs system weight / 2 man carry versus the 250
lbs / 3-6 man carry of the SCR-284), the SCR-288 was not truly replaced in
many applications until the much more rugged and advanced SCR-694 became
available late in the war. The only competitive system of it's time was
the excellent Navy TBX series which had been in service since 1939. This
set however was complicated to operate and it's extreme versatility
sacrificed portability. Even after the introduction of the SCR-694, the
BC-474/ SCR-288 continued to serve in the training of Signalmen at home. |
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The SCR-288 was the first radio set of it's type to be
adopted that was capable of AM phone operation (though as a "Stop
Gap", Limited Procurement and later as a Limited Standard). The
system sacrificed several attributes in favour of light weight, small size
and simplicity which in the end spelled it's success. These were mainly
ruggedness and versatility. In the case of the latter, the SCR-288 could
only be used as a field set, being powered by a hand crank generator and
dry battery (for receive). No alternate power supplies or ancillary
equipment are known of that would have allowed vehicular or semi-fixed
operation as with it's successors." ²
Without any modification, it covers the entire 80-meter
band using AM or CW. The transmitter VFO covers 3500 to 6300 kHz with an
RF power output of 4 Watts. The receiver continuously tunes from 2300 to
6500 kHz. Supply voltage for the transmitter is 6.6VDC @1.65a for the
heaters and 290VDC @ 100mA for the plates. Actually, any voltage between
240 and 320V will do. Originally power was supplied by a hand-crank
generator. Receiver voltages require 1.5 VDC for the filaments and
90-240VDC (B+) either provided by a dry battery or the hand-crank
generator. The watertight case of the BC-474 is painted in Army green,
outside and inside. The front panel held in black with white lettering. It
was indicated to me, that the BC-611 "Walkie-Talkie" frequencies
align with the BC-474, therefore it is possible, that both were designed
to be used together². |
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The set described here was given to me by my friend, Bob Allison
(WB1GCM), who is an avid collector and operator of vintage military radio
equipment. Mind you,- carrying the receiver on board through suspicious customs
officers is another story…All in all the BC-474 is in a good physical state.
The only flaw was, that the antenna current meter didn’t work. The set came
without its legs, the hand-crank generator and the filter FL-10 when I got it.
Apart from some "home-made" legs, the other bits, I learned, are very
hard to find. A matching headset (ANB-H1), a CW-Key (J-38) and a hand-set (C-3)
already existed.
The Receiver, a four tube superhet circuit, is used for the
reception of AM or CW. The tubes have low power consumption. Power is provided
by a battery pack, which fits inside the cabinet, just under the receiver
section. I have used 4x 1,5V D-cells parallel and 20x 9V block batteries in
series to provide the necessary power. The receiver plug is of a 4-pin type,
originally made for use with a Burgess 6TA60 battery pack (or equal).
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Front view
Inside view
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The controls are somewhat limited, but
sufficient. There are a Phone-CW switch, Receiver Tuning and Volume
controls, and Receive-Transmit and Emission Selector (mode) switches. Two
jacks are provided for two sets of earphones. The set only receives if the
headphones are plugged into the main jack. Tuning stations needs a bit of
skills, as there is no real "bandspread" available. However,
when using the set it always surprises me how clear the stations come in,-
almost no background noise,- fairly sensitive too. Considering its rather
"simple" design and in comparison to one of my
"modern" Watkins Johnson (WJ) receivers,- there is sometimes not
much difference between the two,- perhaps a few more knobs to play with on
the WJ…..
As for valves, the BC-474 has four of them located in the
receiver compartment,- 1N5-GT, 1A7-GT,
1D8-GT, 3A8-GT,- easy to get on the surplus market. The 3-tube transmitter
is supposed to have a range of about 15 miles for CW and 8 miles for AM
phone, but I haven’t tested this yet. The manual recommends an antenna
of 35 feet with a 35-foot counterpoise, but for reception any wire longer
than 3 feet does it already. |
The transmitter has all 6V6 type valves, one for the VFO, one
for the power amplifier stage, and one for the AM plate modulator. The controls
are standard for a transmitter of that time,- VFO Oscillator tuning, PA tuning,
and Coarse and Fine antenna controls. To help with the tuning, a PA plate meter
and Antenna Current meter are provided. Standard jacks the key and microphone
are built in.
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The binding posts for the antenna / ground are very close
to the transmitter fine- tuning knob. When both are touched in operation
it will for sure raise your heart-beat! What took a little effort was to
repair the transmitter. The antenna current meter had shortened. By simply
bridging it the transmitter would work again. Finding a replacement meter
was the tough part. The manufacturer, Simpson Electric Co. in Chicago
couldn’t help, nor could the known dealers like Fairradio Sales or
Antique Radio Supplies and the likes.
I spent many evenings on the internet in
finding this specific rectangular bakelite meter. After a lot of
frustration I decided to have it professionally fixed at "any
cost" by a German company specialized in such issues. After
consulting the former owner of the company he mentioned an old ex-employee
of his who could help… and he did. He had in his spares box a 40’s
Siemens "converter / transducer" of some sort that now has the
meter going again. This "miracle box" is out of white porcelain,
has an in and output junction and can not be opened. I don’t know what
happens in there and the older gentleman would not reveal it either. He
gave it to me with a smile saying something like it was priceless and that
he is happy to have an old radio going again…. |
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