DR1200T.5

     A Modification for the DR1200T to prevent lamp burnouts:
				Part 4 of 4 Parts
        From Jim, KD6QVO, Santa Clara, CA, and Lou, KE6EOI, Milpitas, CA. 

     8. Checking the display contacts. Reinstall the display (do not screw 
        to the chassis yet) and power up the radio again. Rotate the 
        frequency knob to insure all the display segments work. If there is 
        a problem, try bending the tabs so they apply more force on the 
        rubber connector. Last resort is to remove the display again, and
        stretch the rubber connector once more.

     9. Now you are home free! Install the switch, notch the case and 
        reassemble.

     After performing this delicate operation, and reviewing the lamp specs. 
     a simpler alternative to the switch would be to use 18V lamps. Here are 
     two equations that predict lamp life and intensity VS operating voltage: 
     Life multiplier = rated volt divided by applied volts to the 12th power. 
     Intensity = applied volt divided by rated volts to the 3.5 power. From 
     this equation 18v will give 20x life at a 41 percent reduction in 
     intensity. 12.5v operation with 14v lamps = 3x life increase, but 
     reduces the transmitter power 10 percent. I operated the 14V lamps at 
     11V to simulate 18V lamps at 13.5v and found the intensity satisfactory. 
     The P/N for 18V lamps is Chicago Miniature CM 7220 or JKL 7220. They 
     should be available from a local electronic distributors or mail order 
     distributors such as Allied in Fort Worth 1-800-433-5700 or Newark in 
     Chicago 1-312-784-5100. I doubt it if radio shack will stock them. 

     We hope the above information will help you.  Address any comments or
     suggestions to me, Jim, KD6QVO.