The 3TF7 Solid State Replacement Module
Location and Typical Installation

 
 
 
 
 

With the receiver upside down and the front panel oriented to the left of the photograph, the module can seen located between the existing power transformer and front, sub-panel of the receiver.  The only wiring is the input and output wires which are kept within the transformer compartment by routing them toward the rear of the radio through the small space between the power transformer and aluminum PTO compartment divider.
 
 
 
 
 
 
 


 
 
 

The entire module mounts without any drilling or chassis modification.  It is securely held in place by the 3 captive screws which hold the power supply transformer in place.  The screws are long enough to  both secure the modules bracket and also secure the power transformer.  An excellent electrical ground to the main chassis is also provided by these screws.

The input and output wires can be seen exiting the left side of the module where they are located between the power transformer and aluminum compartment separator.
 
 
 
 

While the user can choose several methods of electrical connection to the receiver including simply plugging the input and output wires into the existing 3TF7 tube socket, the method at the right is preferred.  The wires from the module are routed into the cable harness of the main chassis by working them through the harnesss lacing.  The 2 wires are then terminated inside the plug shell of P-111.  There, there the existing feed to the 3TF7 is simply routed to the replacement module by unsoldering  a single wire and connecting the module wires per the instructions.  This method offers the advantage of keeping module portability intact.

The 3TF7 tube MUST be pulled from its socket to be electrically removed from the circuit.  I chose to simply route an insulated jumper wire from pin #2 to pin #7 of the 3TF7 socket then reinstall the tube shield.  To all but the most observant, no physical difference is noticeable.
 
 
 
 



Page prepared by: Chuck Rippel
 
URL: http://www.R390A.com
Revision: 02 December 24, 2001
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Patent Pending