[ICOM] PRO III and shut down

[hamop]

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
>
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