Mine doesn't seem to work that way. With PWR set to 100, output is 96 W.
So far, so good. Then, when I hit the PTT, output is 12 W. .I then talk,
whistle, etc. When I'm done, but with PTT still on, output reverts to 12
W. That is with 2.044A. Doug must have been writing about a different
version of firmware.
In a message dated 6/12/2010 8:17:05 P.M. GMT Standard Time,
merlebone@charter.net writes:
This is the write-up that Doug Smith did on the Orion AM ALC. It
is taken from a paper he did on the Orion.
Sorry I can't include the diagram but I think you will get the
idea.
----------------------------------------------------------------------------
---------------------------------
A Unique AM ALC
Here is a novel AM ALC system that sports zero carrier shift and
100% maximum modulation, regardless of transmitter gain and
baseband wave shapes. Refer to Fig 6.
A DSP obtains information about peak transmitter output power
from a bridge, as above. Since it already has information about
its peak drive level, it can compute the transmitter's gain. It
is then relatively easy to find the drive level that produces a
carrier of exactly 25% of the set power level.
An audio compressor is employed that sets the maximum baseband
peak level identical to that of the carrier. When modulation is
performed, the result is a 100%-modulated AM wave. The audio
compressor uses a full-wave rectifier. If the baseband voltage
had a higher negative peak than positive, 100% downward
modulation would be reached in compression before 100% upward
modulation could occur.
Carrier amplitude does not change because the transmitter gain
calculation is performed on the peak-detected combination of
Vc+Mt, where Vc is the peak carrier level and Mt is the peak
modulation level. DSP computes the peak drive level based on
carrier plus modulation; it computes the carrier level based on
transmitter gain. Carrier shift, therefore, is avoided entirely--
Doug Smith, KF6DX.
----------------------------------------------------------------------------
---------------------------------------
When you go to a new band on AM, and say the first word or two,
the Orion DSP does the gain calculation talked about above and
sets the carrier to 25% of the power setting on the power knob
(Using the gain calculation of the radio on that band/frequency).
The actual carrier power will then change as the power knob is
changed. I am using the LP-100 Wattmeter to measure the power out
on my Orion running V2.063X. It is easiest to measure the carrier
on the average power setting on the LP-100 and measure the peak
transmit power on the peak settings (Mic gain to zero to measure
carrier). Once the carrier is set for a particular power setting,
it is stable with just slight (Less then 1 watt change) variation
from the main ALC. On 75M AM the output power drives to 103 W
with the carrier at 25.X watts (The power numbers are accurate to
about 3% and were calibrated with NIST traceable calibrated
equipment). I am sure the accuracy of the carrier level varies
some due to the frequency associated measurement error of the
bridge.
Pretty much as the write-up predicts.
73, Merle - W0EWM
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