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". 

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