[ICOM] PRO III and shut down

Tue Jul 3 00:17:11 EDT 2012

100w on RTTY could be the problem. It is 100% duty cycle, much over 50W 
is taking a chance with a PROIII on RTTY.
    73 Phil N0KE

Bruce wrote:
> There are other possibilities of what could be wrong..
> The power supplies are shutting down when they experience an excessive
> current demand so some caution is in
> order or you may make things worse ie; burned pcb's.
> The finals could be going or one of them..or even the TX predriver on the RF
> unit and associated circuits around it
> like bad diodes for switching RF causing  an oscillation and causing the
> finals to put out way to much RF and tripping the
> power supply over current protection..
>
> -----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
>>
>> ----
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> ----
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> ----
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> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>
> ----
> 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/
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