[TenTec] Jupiter Current Draw / Digital Modes

[Dr. Gerald N. Johnson, electrical engineer]

Voice NEVER draws as much average current as a continuous tone. Its the
NATURE of SSB. ALl there is from SSB is AUDIO. "Weak audio?" Compared to
WHAT? There's no carrier to compare to. Its NOT AM where there's such a
carrier. In radio propagation there are times of weak signals
interspersed in longer times of strong signals. Its called FADING. Has
nothing to do with the radio, but can have something to do with the
antenna and a great deal to do with the propagation path.

The best tool to judge transmitter drive is an oscilloscope. Meters are
the WORST tools. SSB RF output is by nature peaky, and you have to set
up the exciter so the PA isn't overdriven on peaks. When you reach that
condition, there is little you can do to improve the peak to average
ratio in most radios. Sometimes the speech process may improve the peak
to average ratio at the cost of audio distortion.

I don't know the ALC characteristics of the Jupiter but I suspect over
driving it with either audio or tone can back the power down excessively
because of clipping the audio A/D going into the DSP. I heard that type
of problem when a neighbor was testing his new 6N2 on SSB. Too much
audio stopped increasing the output and definitely hurt the audio
quality.

73, Jerry, K0CQ
-- 
Entire content copyright Dr. Gerald N. Johnson. Reproduction by
permission only.