[Elecraft] [K3] K3 FSK power transients

[Julian, G4ILO]

Joe Subich, W4TV-4 wrote:
> 
> With the 8 pole filter I see 2 watts difference on the N8LP 
> LP-100 wattmeter.  However, in AFSK A or DATA A modes for 
> PSK I see as much as 15 watts (0.7 dB) difference (maximum 
> to minimum) as the tone frequency varies from 200 Hz to 2800 
> Hz in DATA A (FC=1500 Hz) or 1000 Hz to 3500 Hz in AFSK 
> (FC=2210 Hz). 
> 
If the fall-off is only at the edges I wouldn't be unhappy with this. Last
time I checked, a few months ago when the power control in data mode was
finally made to work properly, I found that the power output was pretty well
flat between about 400 to 2400Hz, once the audio level has been adjusted for
4 bars of ALC as instructed. Personally I wouldn't operate with a sound card
program outside of that range, anyway.

If you are transmitting some sort of wide FSK mode then I suppose you will
see differences because the ALC can only keep the power level average. I
guess this is where having the option to set TX EQ in data mode could come
in useful, though whether the adjustment currently permitted is fine enough
to cancel out filter ripple is another matter. I wouldn't have thought any
other radio would do any better, though. With many radios you have to keep
the drive below the ALC threshold so you are completely at the mercy of the
sound card frequency response and the TX filter ripple.

-----
Julian, G4ILO. K2 #392  K3 #222.
* G4ILO's Shack - http://www.g4ilo.com
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