Previously the station had several modules for taking care of computer interfacing, soundcard interfacing
conrol sharing by computers or radios, and general station configuration control and status display.
All these functions are combined into a single control box. The basis of this is the adaptation of the
N3FTI Automated Transceiver Band Switch board. This board was designed to take BCD signals from a computer
parallel (LPT) port and control the configuration of a multi-band VHF/UHF/MW station. The 14 DPDT relays
were controlled by a BCD decoder. The board was adapted so that control either was manual thru the use of
toggle switches or via RS-232 control signals. In addition, a home-made audio interface using 600-ohm 1:1
transformers provide audio interface between radio mic and speaker or other audio input/outputs. A DEMI
sequencer board is embedded to handle timing and sequence of station components. Switching between two
Radios provides SO2R (single operator; two radio) functioning.
Update for August, 2011:
Amazing how a change in the station simplifies things. I recently sold the FT-847 after 13-years
of reliable use. But in 2010 I made a decision to switch to use of modern Transverters to be used
with the superior performance of the Elecraft K3. This conversion is almost complete pending receipt
of the DEMI L432-28 (est. Nov.) and construction of the DEMI 222-28 transverter kit (est. Dec.).
With only one radio to control the station and its simpler computer interface requirements the control box
has several redundant or un-needed circuits. To illustrate this I modified the first block diagram to
show only the circuitry required for use by the K3. Compare that with the first diagram to the left on
the line of original photos. Also, added new TR-relay interlock control board.
The new diagrams:
Several photos and diagrams provide details: (click image for larger view):
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