>Let's not forget the TS950SDX, which suffers from the same problem.
>
? Only for those who believe that way mo' ALC is way mo' betta
Not so. I'm not an idiot, Rich. I always set the carrier control according
to Kenwood recommendations -- meter deflection within the ALC zone.
Actually, I normally set it as low as possible, just under the point where
the output stops rising. But my 950 spikes with meter deflection anywhere in
the ALC zone, even when set to just start indicating at the bottom of the
zone, as you have recommended. The rig was checked by a factory-authorized
technician, who found the ALC to be correctly adjusted and working to specs.
The only thing that reduces the frequency of the spikes is to increase the
CW waveform rise time. Amazingly enough, the 950 has a menu setting to make
this 2ms, 4ms, 6ms or 8ms. As the rise time is increased, the spike
frequency is reduced, but never eliminated.
In my opinion, it's a design problem: if you look at the transmit timing
curves in the 950 service manual, you can see that after a 15ms delay, CW
output is initiated by a sharply-rising square wave signal called CKY. A
signal to turn on the ALC is initiated at exactly the same time, but rises
and decays more gradually than CKY. In my opinion, this sometimes allows the
output to spike to the max before the ALC has turned on. The timing is
probably very close, one way or the other. By increasing the CW waveform
rise time, the ALC has more time to catch up. Just a theory.
By the way, the spikes are easily observed on an 87A amp, which fault trips
in response. All I have to do is send a steady stream of dits in QSK mode.
Neither an FT-990 nor an FT-1000mp has ever driven that fault.
Once again, I think you've taken incomplete data and extrapolated to an
erroneous general conclusion.
73, Dick, WC1M
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|