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Author Topic: Icom 756 pro 3. remote civ keeps going bad.  (Read 1971 times)
N4ZY
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Posts: 81




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« on: October 15, 2012, 12:22:13 PM »

i have ic 756/3 and i have had to replace the civ output 2 times. i keep checking for a rfi problem but cannot find one. then i am told that it could be static electricity coming in from cable/phone line etc.
any one have ideas how to solve this. getting costly.
                             Jim N4ZY
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W9GB
Member

Posts: 2623




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« Reply #1 on: October 15, 2012, 06:35:39 PM »

Put an Opto Isolator where the Icom connects your Icom CI-V serial network bus.

That simple 2-wire system can easily act as an antenna (just like stereo speaker wires)
for stray RF or Common-mode RF issues from your antenna, that you have not addressed.

DF4OR - Primer on the Icom CI-V serial (network) bus
http://www.plicht.de/ekki/civ/

CIV / CI 5-Communications Interface-V Reference Manual
http://www.icomamerica.com/en/support/kb/article.aspx?ArticleNumber=63AE624429

Greg Ordy, W8WWV - Yet Another ICOM CI-V Interface
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/CIVInterface.htm

The Icom CI-V serial bus was conceived, designed, and first offered in the early 1980s.  
For that time, it was state of art for an inexpensive amateur radio solution,
BUT as K9JM discusses below -- they had no method for message management (collisions).

James A Michener, K9JM
ICOM CI-V Router -- using Arduino
http://www.k9jm.com/CIV_Router/CI-V%20Router.html

Bring new technology to a legacy bus.
http://www.k9jm.com/CIV_Router/Riding%20the%20CI-V%20Bus.pdf
« Last Edit: October 15, 2012, 07:04:22 PM by W9GB » Logged
N4ZY
Member

Posts: 81




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« Reply #2 on: October 16, 2012, 06:45:23 AM »

Jim, thanks for reply. what is taking place i do not know. the output in the 756 pro 3 gets damaged. i am running a westmountain p/p for a interface. . so open for all ideas.
  Jim
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AA4PB
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Posts: 12854




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« Reply #3 on: October 16, 2012, 08:04:02 AM »

Is there any correlation between lightning storms and the failures? Perhaps there is a station grounding issue. The output of the CIV is an open-collector transistor circuit operating at 0/+5V levels so it is not particularly sensitive. I would not expect RFI from the antenna at the 100W level to generate enough energy in the CIV cables to do any damage.

I assume no damage is being done to the CI-V interface in Rigblaster interface. It works at the same voltage levels.
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K8AC
Member

Posts: 1475




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« Reply #4 on: October 16, 2012, 10:20:07 AM »

Not an uncommon problem.  I suggest you look carefully at your grounding scheme and make sure that you have all of the pieces of gear grounded to a common point in the station and that includes your PC and whatever interface you're using.  With the usual lightning storms we get here in the Southeast (I'm in NC), nearby strikes can induce enough voltage in the various lines entering your station that it's easy to end up with a large potential difference between units if they're not properly grounded.  It's also not uncommon for guys to overlook grounding their PC cabinet to the station ground in the shack.  In the older Icom gear, the CPU was protected from surges on the CIV line by a 15 cent transistor which was relatively easy to replace.  Maybe it's more complicated in the Pro 3.

73, Floyd - K8AC
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N4ZY
Member

Posts: 81




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« Reply #5 on: October 21, 2012, 09:19:17 AM »

thanks all. i will re examine my ground system. the computer IS NOT grounded.  JIM
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