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MARINE RADIO EQUIPMENT
If you have just visited the historical section, you must
have wondered what kind of equipment was used in the 1920's and how many
times it must have been updated since the SS Cape John is an active craft in
2005 in the RRF service. We do not know the answer to this question
but surely being an antique radio archive and understanding the technology
that existed before 1930, the radio rooms of ships were very primitive by
today's standards. The earliest STS (Ship to Shore) equipment was
spark gap. By the time that the Santa Ana (later renamed SS Cape John)
was built, spark gap transmitters were out and CW A1 transmission was in.
During the period of the late 1920's to early 1960's, this equipment was
being replinished with newer more advanced equipment. In 1962 all of
the equipment was removed and the RCA Radiomarine Division provided and
installed its new Model 6U Radio Console. This was a state of the art
communications console. The below diagram shows the console as it was
installed in the radioroom on the SS Cape John.
The middle top and right top section contain the two
transmitters that we have preserved. As earlier described the
receivers and emergency transmitter were previously sold. But all of
the control meters, switches, controls and auxiliary panels have been
preserved as well. One of the primary reasons for saving this
equipment is to put the HF transmitter back onto the air. Needless to
say, this will take some time and trouble, but all is worthwhile when
preserving the past! The power supply-modulator assembly was installed
in the lower part of the middle rack.
The Transmitters
We have preserved two of the primary transmitters from this
console. The ET8051 MF Transmitter is a 1962 - 250 watt A2 mode or 200
watt A1 mode telegraph transmitter. This transmitter uses 8 pre-tuned
frequencies ranging from 350 to 515 kc. frequency range.
This is the primary
transmitter used by ships to transmit on any of 8 low frequency channels
The transmitter uses a
pair of 807's that drive a pair of 813 output tubes
Note the large diameter
coil for tuning these low frequencies
The ET8065 HF transmitter is a 1962 300 watt telegraph
transmitter that operates in A2 or A1 mode from 2000 to 24,000 kc. frequency
range. It uses 2-813 power amplifier tubes and is crystal controlled
by a separate crystal oscillator.
This transmitter
operates from 2 to 24MHz. It is crystal controlled but the various
marine bands
are achieved using harmonic frequencies and other tuning technics.
Note the charts showing
settings for obtaining various marine frequencies.
Top view showing the
807's that drive the pair of 813's in the final
No belts on this old
beauty. Band changing is done via "Chain Drive" !
Both transmitters were removed in 2002 from service where it
was operationally tested before removal. There was an emergency
transmitter and two marine receivers that were part of the console that were
previously disposed of before we obtained this equipment. As you
see in the following pictures, the equipment uses super heavy-duty
construction and the power supply/modulator assembly by itself weights about
300 pounds! The power supply was built to operate both transmitters,
but only one at a time. Talk about a true "boat-anchor".
Click for the History of
this ship
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