FW: [Elecraft] Running an ICOM PW-1 Amp with the K3

Thu Dec 25 22:59:03 EST 2008

Hi Tom, Mike, and All,

Yup, I forgot to mention that I synchronize the band switching between the
K3 and the PW1 manually_ sorry about that.  Obviously, it's very important.
The amp might be able to protect itself from a mismatch of bands, or
over-driving for that matter, but I don't want to test it.

It's not too hard for me to remember to change the amp's band switch though,
because these days of no sunspots I operate on 20 meters 90% of the time
anyway.  When I occasionally go to another band, I either run barefoot at
100 watts, or am careful to switch the amp.  Of course, when I go back to 20
meters QRO, I need to remember to turn down the drive from the K3 to 20
watts (or 25 watts maximum, which gives me 800 watts out from the PW1).

I wish I had a way of automating the band switching and control of the K3
drive via alc, but it is over my head to figure out how to hook it up.  If
anyone out there has accomplished that, I'd be glad to hear how they did it.

Again, I'm not recommending anything, but just sharing my own experiences
FWIW.

73,  John

-----Original Message-----
From: Tom Hammond [mailto:n0ss at embarqmail.com]
Sent: Thursday, December 25, 2008 10:59 AM
To: John E. Reiser
Subject: Re: FW: [Elecraft] Running an ICOM PW-1 Amp with the K3

Season's Greetings John:

Y'know, when we were originally beating this around, I failed to ask about
auto-band switching. Since there's no mention of using the CV-I interface,
I'm assuming you're merely manually changing the PW-1 from band to band
rather than attempting to use the K3's serial band output data?

Several of us have been discussing this (band switching) problem directly
amongst ourselves, with not a lot of what we considered to be 'suitable'
solutions... without having to add additional interfacing circuitry.

Any thoughts?

73,

Tom   N0SS

At 09:32 12/25/2008, you wrote:
>Hi Mike, W4UM,
>
>See below.
>
>Merry Christmas!
>
>John, W2GW
>
>
>-----Original Message-----
>From: John E. Reiser [mailto:reiserj at optonline.net]
>Sent: Monday, December 01, 2008 4:20 PM
>To: Tom Hammond; elecraft at mailman.qth.net
>Cc: Jerry Liley K0GUG
>Subject: RE: [Elecraft] Running an ICOM PW-1 Amp with the K3
>
>
>Hi Tom,
>
>I have been driving my Icom PW-1 with my K3 for nine months now without any
>problems.  I use it for CW, SSB and digital modes.
>
>I simply have a coax jumper between ANT1 on the K3 and Input 2 on the PW-1,
>of course.  And PTT is accomplished by means of a shielded cable from Radio
>Shack that has RCA plugs on each end.  I don't use any connection for ALC
>with the K3.  However, I am very careful not to overdrive the amp.
>
>Let me explain.  My "other" radio is an Icom 756 Pro 2.  It gets very
little
>use anymore, but I left it connected to Input 1 on the amp.  Besides a coax
>jumper, the Pro 2 is connected to the amp with a special cable provided by
>Icom.  The cable provides for PTT and ALC.  When one first sets up the amp,
>one is instructed by the manual to calibrate the ALC.  This is accomplished
>by means of a screwdriver adjustable potentiometer on the back of the amp.
>The meter on the front panel of the amp has a switch-selectable ALC scale
>with a red line mark at mid-scale.  The ALC is calibrated by adjusting the
>pot such that the needle does not go past the red mark.
>
>Two identical sets of input jacks and ALC-calibration-pots are provided on
>the amp, for Input 1 and Input 2, respectively.  Before I connected the K3,
>I calibrated the ALC on the Input 2 side using my Pro 2.  My thinking was
>(correctly or not) that as long as I controlled the drive from the K3 so
>that the ALC meter on the amp stayed below the calibrated red mark, all was
>well.
>
>Now, when I use the amp, I set the output of the K3 to 20 watts.  That
gives
>me about 600 watts out, as measured on my LP-100A watt meter.  The ALC
meter
>on the amp stays within the lower (leftmost) third of the scale.  The
>overdrive-protection circuits in the amp have never activated.  The
>difference between 600 and 1000 watts out is negligible at the receiving
>end, of course.
>
>With the Pro 2 I used to set the drive to just give me 1K out, although I
>could have pushed it to 1100 or 1200 on some bands.  It took about 25 to 30
>watts of drive.  Of course, with the ALC connected, the ALC never went past
>the red mark on the meter.
>
>So, bottom line, I am able to use the PW-1 with my K3 but, without ALC, I
>have to be careful.  In writing this note, I'm merely sharing my own
>experience, in case it can help someone.  Others may have a better
solution,
>perhaps using the negative-going ALC mod to the K3.
>
>73,
>
>John, W2GW
>
>
>-----Original Message-----
>From: elecraf at mailman.qth.net
>[mailto:elecraft-bounces at mailman.qth.net]On Behalf Of Tom Hammond
>Sent: Monday, December 01, 2008 11:00 AM
>To: elecraft at mailman.qth.net
>Cc: Jerry Liley K0GUG
>Subject: [Elecraft] Running an ICOM PW-1 Amp with the K3
>
>
>I'm about to loan my K3 to another local ham who currently has an IC-7800
>and PW-1 amplifier.
>
>His IC-7800 has been sent in for service so it's temporarily out of
>the
>picture. However the PW-1 is still in play and this local is gonna want
>to use it with the K3.
>
>Is anyone running a PW-1 with their K3?  If so, please contact me a.s.a.p.
>so I can exchange some info with you.  Specifically I need to know what it
>took to interface the two devices and to get them to function without any
>hiccups.
>
>Appreciated.
>
>73,
>
>Tom Hammond   N0SS
>
>
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