[Icom] Icom Pro II and PW-1 (Do I have a problem here!)

Thu, 27 Jun 2002 04:19:10 -0700

Hi Bill,

The ALC in the PW-1 will hold the exciter output at the level required to
drive the amplifier to the preset power output. If the PW-1 requires 80W of
drive to produce 1kW output. turning the transceiver's RF POWER control up
to full output will make no difference, as tithe ALC line is regulating the
drive level.

As the ALC is the amplifier's first line of defence, it is absolutely
mandatory to set it up correctly. Assuming that your Bird power meter is
accurate to within 5%,another method is to adjust the ALC for a reading of 1
kW (into a dummy load!)

Best 73,
Adam, VA7OJ/AB4OJ
North Vancouver, BC, Canada
http://www.qsl.net/ab4oj/
Note new e-mail address:
mailto:[email protected]

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Bill Tarkington
Sent: June 26, 2002 21:07
To: [email protected]
Subject: [Icom] Icom Pro II and PW-1 (Do I have a problem here!)

Having recently purchased a Pro II, I followed the owner manual instructions
for both the amp and radio to set the ALC level on the amp so as not to
overdrive it and risk FET damage.  Once all proper connections are made,
book says to adjust the exciter (Pro II) output to 100W, then turn ALC
adjustment screw clockwise slowly while key down on either CW/RTTY and at
same time reading the ALC scale on the PW-1 control head until meter needle
is dead on the ALC adjust mark. Once adjusted thusly, key down at 100W from
the exciter and check PW-1 power meter to insure 1KW output.  Did all this
and all looked to be okay.  HOWEVER, I noted that the RF power knob on the
ProII was not fully clockwise (wide open).  Advancing it to full open seemed
to indicate the Pro  II was putting a little something in excess of 100W per
its power meter.  Bottom line is, I do not know what meters to trust here.
Out of curiosity, got out the Bird 43 Watt meter with 1000W slug therein and
did some checking. First used the Bird meter with 100W slug to set barefoot
output on the ProII at precisely 100W and left it there(  little less than
full open). Further testing with the Bird in and out of the circuit with the
PW-1 output seems to indicated the Pro's watt meter is pretty accurate, but
the power meter on the PW-1 is reading low.  If do the ALC adjustment using
the PW-1 power and alc meters per book,Bird says full amp output is 860W,
not 1KW the PW-1 watt meter indicates. If do the ALC adjustment using just
the Bird meters readings while ignoring the PW-1, the ALC goes into the red
some little way, and the output per the Bird is about 1250W.  All this
leaves me wondering which watt meter to trust to obtain the full 1KW output
of the amp. If use the Bird and guess wrong, will 1250W out with ALC being a
little in the red likely cause me some amp damage?  The safe thing to do, of
course, is go with the PW-1.. BUT, I want them to agree more or less with
one another or understand why not.  Incidentally, if it matters, all tests
were done into a  1500W dummy load.  Am I missing something here?  Comments
please. Bill, K3YC

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