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

Thu, 27 Jun 2002 11:00:05 -0500

Thanks for your response and experience Larry.  I will probably play it safe
and go with just the pw1 meter's reading, at least until can determine the
accuracy of the Bird.  I can live with 850 out instead of 1000 if that is
the case and probably will never know the difference.  Just am uncomfortable
with these type of little mysteries.  It is good to know though that I am
not alone in what I am seeing.  Your second comment about minimum exciter
output to achieve full amp output is very interesting and I will most
certainly check that out too. Thanks again. Bill, K3YC
----- Original Message -----
From: "Larry Gauthier" <[email protected]>
To: <[email protected]>
Sent: Thursday, June 27, 2002 8:02 AM
Subject: Re: [Icom] Icom Pro II and PW-1 (Do I have a problem here!)

| Bill,
|
| I don't think you have a problem... aside from what looks like wide
| tolerances for wattmeter calibrations.
|
| My PW-1 disagrees with my wattmeter by about +10% at the high end of the
| scale - which is to say that when my wattmeter reads 1000 watts the PW-1
| reads about 1100; and by about -10% at the low and of the scale -
wattmeter
| says 100 watts, PW-1 reads about 90. I adjusted my PW-1 based on the
| wattmeter reading 1KW and the PW-1's ALC meter at the set point. [why do I
| trust my wattmeter more than the PW-1 meter? -- because it allows me to
get
| more power out! ;-]]
|
| The interesting reading is when you reduce the drive power from the
| transceiver (an IC-746 in my case) to see at which point the ALC clamps
the
| amp's output power. [Reduce drive power to minimum, then slowly advance
| drive until output reaches max (the 1000 watt point). Put the amp in
| standby, and measure output power from your transceiver.]  For me, it only
| takes about 55 watts of drive to hit 1 KW out from the PW-1... which means
I
| can run my transceiver much leaner (and cleaner I hope) and still deliver
| max out from the amp.
|
| Probably the only modes where you would need to worry about 1000 versus
1250
| watts is one of the solid carrier modes like RTTY or PSK -- and I never
| operate those modes at full output anyway. So, at least for me it would
not
| be an issue.
|
| -larry
| K8UT
| ----- Original Message -----
| From: "Bill Tarkington" <[email protected]>
| To: <[email protected]>
| Sent: Thursday, June 27, 2002 12:07 AM
| 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
needl
| e
| > 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
| >
| > ----
| > Your Moderator: Dick Flanagan W6OLD, [email protected]
| > Icom FAQ: http://www.qsl.net/icom/
|
| ----
| Your Moderator: Dick Flanagan W6OLD, [email protected]
| Icom FAQ: http://www.qsl.net/icom/