I have seen overshoot in the TUNE mode.
-John NI0K
Don Wilhelm <mailto:donw...@embarqmail.com>
Sunday, March 10, 2019 2:40 PM
I am left wondering if some K3 users who are seeing "Overshoot" are
actually seeing what is referred to as "Power Hunting".
That would occur mostly in Voice or DATA modes when the audio level is
not set high enough.
With insufficient audio, the K3 can initially go up to the set power,
and then will quickly settle back to a low power, and then gradually
climb to the full power set by the power knob - that behavior is
seldom seen in CW mode, but can be seen in DATA modes and Voice modes
if the audio levels are not set correctly.
The cure for that behavior is to drive the audio as indicated in the
manual. For voice modes, adjust the MIC Gain to produce 5 to 7 bars
on the ALC meter.
For DATA modes, adjust the audio levels to produce 4 bars solid with
the 5th bar flashing.
If your data mode application has a "POWER" slider, it is not properly
named (complain to Joe Taylor) - it is just another audio level control.
The Elecraft transceivers control power differently than all other
amateur transceivers, so ignore the common internet advice to control
the power with the audio level. Set the audio as indicated in my
website article (same information is in the K3/K3S/KX3/KX2 manual) and
adjust the desired power with the POWER knob.
Other transceivers may be able to use the audio level to control the
output power, but Elecraft transceivers are different, do not "do it
that a-way".
Look at the article on my website www.w3fpr.com. Scroll down the left
column and click to open the document.
BTW: The originator of this thread is now on the right track, I have
exchanged several email messages with him (and I built his transverters).
73,
Don W3FPR
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Jim Brown <mailto:j...@audiosystemsgroup.com>
Sunday, March 10, 2019 2:02 PM
I've had an LP100 in line for several years, always set to read peak
power, and the most overshoot I've seen from either of my two K3s is
less than 1 dB. The K3s are driving a pair of 87As, and I have NEVER
used ALC between rig and amp.
The earliest advice I've seen about this was in the user manual for
the Ten Tec Titan 425, designed around 1979, and using a pair of the
same 3CX8007 triodes used in the 87A. The manual said that ALC output
was provided only for historical reasons, and advised against using it
to control output power.
When you look ONLY at output power, you miss the mess that ALC causes.
To see it, you must look at (or listen to) the transmitted frequency
spectrum. A P3 on a second radio, or an SDR receiver will clearly
reveal the splatter and clicks.
73, Jim K9YC
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John Simmons <mailto:jasimm...@pinewooddata.com>
Sunday, March 10, 2019 1:34 PM
Wes,
Once I got my LP100, I began to see the same behavior with my K3. This
type of output anomaly is a huge reason to use ALC.
73,
-John NI0K
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Wes <mailto:wes_n...@triconet.org>
Sunday, March 10, 2019 9:39 AM
Indeed. Folks who would never think to turn off the AGC in their
receivers get weak-kneed at the thought of AGC (ALC) being used in the
transmit loop. In "Fundamentals of SSB", Collins radio speaks of ALC
(pp.7-10,11) without any negativity, and in fact calls it a form of
speech compression. As in many things, the devil is in the details.
I suspect most of the Elecraft faithful would also be surprised to
know that their beloved K3s use internal ALC as well as digital power
control. This is not perfect, I've observed overshoot, power slowly
increasing to set level and low level power jitter*.
* You need a spectrum analyzer to see this and it's unlikely to be
heard on the air, but it's there.
Wes N7WS
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