[ICOM] PRO III and shut down

[hamop]

Thanks. Bruce, I have a LATE PROIII, about December of 2010 with the newer 
finals from the original IIIs.   I just now went to a dummy load and had 100 
watts output but after transmitting  dits and dashes for just about 15 
seconds, a rather quick loss of ALC and power to 5 watts. So, no amp issues 
and grounds good and using 1:1 dummy load. This has never happen before. 
Even have used RTTY at 100 watts quite often with 150 countries worked since 
last November. And some of that was rather constant calling a DX station. CW 
DX calling for hours and no problems. But as of today ( and I did call a DX 
station for 10 minutes today before this happened ) since problem happened, 
just a few seconds of XMIT and have to turn PS125 AND PRO for 5 mintues or 
more and then get 15 seconds of OK transmit power. Again, receiver is fine 
and ALC is great during that time.
TU for comments ..
San K5YY

-----Original Message----- 
From: Bruce
Sent: Monday, July 02, 2012 5:20 PM
To: 'ICOM Reflector'
Subject: Re: [ICOM] PRO III and shut down

Does it happen on ALL bands? Could be drivers ready to go and causing a
intermittent short, the drivers, 2SC1972's were very
finicky with their bias..factory at one time was setting the bias current to
high.

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of hamop
Sent: Monday, July 02, 2012 3:16 PM
To: ICOM Reflector
Subject: Re: [ICOM] PRO III and shut down

Ken, it happens with the amp off, and everything is the SAME as it has been
for 2 + years now and never a problem. Same good ground etc.  Just tried the

PRO III again and after just keying down about 10-15 seconds, the PRO went
off. I am not running the amp, only 100 watts output. And, I have to turn
off the PS125 also, if just turn off the PRO III for several minutes and
back on > no output. If I turn off the PS AND PRO III for same minutes, all
comes back to 100w. So it is not just turning off the PRO that is necessary.

But, when back on line, I can maybe transmit a few seconds before shutdown
to 5-6 watts, no ALC etc.  Thanks for information.
San K5YY

-----Original Message----- 
From: Ken Sands
Sent: Monday, July 02, 2012 5:07 PM
To: ICOM Reflector
Subject: Re: [ICOM] PRO III and shut down

Make sure ALL your (HEAVY) grounds go to a (HEAVY) common point and then to
a cold water pipe ground or other GOOD ground system..
It seems you are feeding RF back from the linear to the Pro 3.

My 2 cents,
Ken K8TFD

On Mon, Jul 2, 2012 at 5:59 PM, hamop <k5yy at cox.net> wrote:

>     Hello all ... need some assistance. Never had this situation happen
> before. Today while operating on 20m CW I noted no output, well maybe 5
> watts, and I thought maybe the PS125 had blown an internal fuse for some
> reason. I was running about 50 watts to a Titan amplifier at the time, my
> main setup for 3 years now. Well, rather than tear into the PS125, I put a
> PS85 in line and again a full 100 watts immediately. So thought the PS125
> had truly blown a fuse. Well, after another shutdown to about 5 watts I
> thought the PS85 had also blown a fuse.
>    As one last effort, after about 5 minutes, I returned on the PS125 and
> PRO III and a full 100 watts output again. I found out that if I turned on
> the rig and did NOT hook the PTT line to the Titan, all seemed to be OK
> with no "shut down".  But, even keying the amp with an EXTERNAL foot
> switch
> and trying to drive the amp, bang ... again just 5 watts out, but it
> returned to 100 watts after another 5-6 minutes.  Is the PRO III or PS125
> and PS85 ( unusual for both to do it) heating up inside causing the
> shutdown by some quirk feedback from the Titan amp?  Seems like if just
> barefoot straight to the antenna, I can transmit 100 watts as normal with
> NO shutdown. Puzzling to me for sure. Appears since same thing happened to
> the PS 125 and 85 that both should not have developed the same 'shut down'
> issue. That leaves me wondering if my PRO III finals are overheating some
> how?
>   Thanks for any suggestions.  Receive is fine the entire time. If I shut
> down the PS and PRO III for just 3-4 minutes, the output may drop quickly
> with about 20 seconds of CW and the longer units are off , the longer the
> power stays up.
> 73
> San K5YY
>
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
>
----
Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/
To support QSL/QTH.net: http://www.qsl.net/donate.html

----
Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/
To support QSL/QTH.net: http://www.qsl.net/donate.html

----
Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/
To support QSL/QTH.net: http://www.qsl.net/donate.html