[Hallicrafters] SR-400 power out

[Jim Liles]

Hi Tom,
The SR-400 is good for about 200 watts out and the SR-400A 275.  175 is not shabby for 6HF5's.  The most common problem with the SR- 400, 400A, and 2000 is low drive which can be corrected with proper alignment.  The drive is adequate if the plate current increases then drops off as the transmit rf gain is increased.  All three radio's are sensitive to alignment because they force the CW and tune carrier through the crystal filter at the -30DB point of the skirt.  Whistle it up in sideband mode and if you can get ALC at the 6 position of AF gain, the power out is as good as the tubes are capable.
Kindest regards Jim K9AXN