[ARC5] Abrams Main Battle Tank Gets Radio Upgrade.

[David Stinson]

"M-1" on 274N antenna relays and on BC-348 receivers 
denotes the addition of a 1-megaOhm 
resistor from the antenna connection to ground.  
It drained-away the static-electric charges on antennas
that so plagued early aircraft radio.  Many elaborate
"Rube Goldberg" devices were tried before finding this 
simple solution.  I have the tech order here somewhere.
I don't remember if it included the SCR-274N receivers.
I thought the ground straps were a post-war change,
but I can't remember for sure and good Lord only knows
were my folder of tech orders is buried.

73 Dave S.