[Milsurplus] MAB vs BC-611

[Mike Morrow]

Hue wrote of the BC-611 RF output:

> i believe the manuals right - it's a few milliwatts, not 100's of milliwatts.

The manuals I've seen say ".035 watts" output, but I contend that it should be "0.35 watts" output.  The PA tube plate, when using an A-battery with reduced voltage of 90 vdc, should according to the manual have about 70 vdc on the plate and draw 7 mA when the tank coil is properly dipped for minimum current.  That would be about 0.49 watts input.  If a fresh A-battery (103.5 vdc) were used, the plate voltage would likely be about 83 vdc, so 7 mA plate current would cause 0.58 watts input.  The PA appears to be a fairly garden-variety class-C amp, which should have perhaps 70 percent or better efficiency.  So a reasonable power output expectation would range from about 0.34 to 0.41 watts.  A power output of only 0.035 watts would mean that the PA efficiency was only about 7 percent!

I am talking only of PA stage RF output.  PA power of 0.4 watts at 4 mc into that short vertical antenna with non-existent ground plane must have a resulted in an abysmally low effective radiated power.

IIRC, the MAB/DAV was rated for 0.2 watts PA RF output.

73,
Mike / KK5F