Posted by
Don Wilhelm-3 on
Feb 11, 2006; 5:44am
URL: http://elecraft.85.s1.nabble.com/SSB-Power-tp386507p386509.html
Matt,
I would surmise that you are being confused by your external wattmeter. The
XV50 LEDs will flash on voice peaks, but if your wattmeter is showing you
average power, its indication will be much less than the peak power.
This 'confusion' leads many folks to overdrive their equipment on SSB. The
K2 has a good indicator in the ALC LED display. If you see the ALC
indicator lighted at all, you are driving to the proper peak power. This
can be observed easily on an oscilloscope - first observe the amplitude of
your power setting in CW, and then switch to SSB. If the voice peaks come
up to the same amplitude as you observed for the CW signal, you are
achieving that same level of PEP (peak envelope power). The average power
will be considerably less than the PEP power for SSB.
73,
Don W3FPR
> -----Original Message-----
>
> I'm a little confused about measured transmitted power when in SSB vs
> CW.
>
> As an example, I have an XV50 Transverter that is adjusted to produce
> 20 watts RF out when using the K2 'tune' control. This output is
> adjusted by reading 20 watts on an external power meter. The power
> indicator LEDs are then adjusted to read 20 watts as well.
>
> When using SSB, however, the RF out is much, much lower, maxing out at
> 7-8 watts PEP on the external power meter. The indicator LEDs,
> however, indicate 10 - 20 watts of power.
>
> I'm not certain I know how to understand what it is I'm measuring. In
> my mind, I think much the 20 watts RF out of a CW signal is actually
> carrier and of not much use. When in SSB, I want to think that I can
> still put out the 20 watts, only now all concentrated in one sideband.
>
> Why does the power meter fail to show the 20 watts?
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