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Author Topic: ICOM IC-7400 low power with 1.4-1.5 SWR  (Read 6893 times)
CT1EWX
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Posts: 14




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« on: October 25, 2012, 02:36:07 AM »

Hi friends.
I have now the radio ICOM IC-7400, firts look the rx is good ( on cw ), better than my Kenwood TS-2000 with the Inrad filter.
but I was surprised because, on TX with 1.4 or 1.5 or more of SWR, the output power is cut to 60-70W no more.
this is normal on this radio model??, or is there a menu to close this situation???.
thanks to all.
Sérgio lopes
CT1EWX

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N4NYY
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Posts: 4913




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« Reply #1 on: October 25, 2012, 06:43:07 AM »

Is that the radio that is the same as the 746?

If that is the case, check it in all modes. It could be a driver failure, or the dreaded IC-151.
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AE4RV
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« Reply #2 on: October 25, 2012, 10:55:16 AM »

It is a 746 pro and it is normal for that rig to start cutting power output when the SWR gets above somewhere between 1.4 or 1.5. Get a tuner if you need to.
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N4NYY
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« Reply #3 on: October 25, 2012, 07:22:54 PM »

It is a 746 pro and it is normal for that rig to start cutting power output when the SWR gets above somewhere between 1.4 or 1.5. Get a tuner if you need to.


Cutting 30 watts at a 1.5?
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AE4RV
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« Reply #4 on: October 26, 2012, 07:33:02 AM »

Yes. Known issue with both pro and non-pro 746. I've owned a 746pro since 2004. The radio is trying to protect it's finals. Some say aggressively so.

Via WB8B QRZ page re: Icom 746: " over sensitive swr power fold back at only ~1.5:1"

http://www.eham.net/ehamforum/smf/index.php?action=printpage;topic=23258.0

On this page: http://forums.qrz.com/archive/index.php/t-311813.html?s=219ad21a2869fc0edeef1dc3d9f452cd
W1QJ states: "My radio Icom 746 has an aggressive swr foldback circuit. It begins to fold back at 1.2 to 1 swr and it reduces power quickly. "

On this page: http://forums.qrz.com/archive/index.php/t-21244.html
KD5NCO states: " I also know that with this rig [746pro] any SWR at 1.5:1 will cause the power (70W) to fold back to about half (35W) and any SWR above 1.6:1 will drop the power like a rock."

Solution: Use a tuner.
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