Final temperature

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  • Question
  • Updated 1 week ago
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  • (Edited)
I often run maximum power in Digital mode (FT8). Can this harm the final from my Flex 6500?
My DDutil temperature readings are 60 degrees celcius when i run maximum power.
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Geert Balsma PA3CPS

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Posted 2 years ago

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Bob Gerzoff, WK2Y

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Is the fan going into high speed?  
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Geert Balsma PA3CPS

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I don't no. My Flex is located in another room. But i can test that.  
(Edited)
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Mark WS7M

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don't take this as "the word" but I think the flex is pretty well protected if temp gets too high I believe things are shutdown.  Hopefully someone more knowledgeable will weigh in.

But to be sure I power limited my radio to 75 watts in the radio setup.

I also typically use my amp.  I set my flex to like 3 watts which drives my SPE 1K to about 175 watts.  

With my lousy antenna this probably works out to an ERP of like 50 watts (sigh)
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Ken - NM9P, Elmer

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I run my 6500 at close to full power, (about 80 watts to make sure my signal is always clean) and with the 15 seconds on / 15 seconds off duty cycle, the rig hardly knows it is transmitting. I have not had the fan go to high speed,

On JT-65/JT-9, it is another story. It often hear the fan switch up to high after several QSO's in a row in those modes. Though the temp never seems to get excessively high.

Btw... your rack mount looks very clean, neat, and tidy.
As long as you have adequate ventilation.....

Ken - NM9P
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Bob G W1GLV

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Why so much power, I''ve made plenty of contacts around the world at 15 watts maximum.
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Kevin Darrah

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It's nice when someone runs some power so I don't have to try and copy piss weak stations on a regular basis...
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Ken - NM9P, Elmer

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Ft8 only copies reliable down to about -20 dB. If you are only -23 and go from 15 to 60 Watts, that is a 6 dB increase, taking you to -17 dB. The difference between a good contact and not being heard at all.
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Mark WS7M

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I use as little as possible.  I have run my amp with 1 watt out from the Flex.  That gives me about 40 watts created at the amp.  I have a pretty lousy antenna and I would figure with coax loss and antenna inefficiency that I am radiating (with 35 w from the amp) about 20 watts.

I usually start there.  If I am not heard I bump up 1 watt on the flex. At 2 watts I get 80 from the amp.  Again I figure ERP is about 50 perhaps. I keep working it up as I need to.

I find when I have the amp running about 80 W that I can get to almost anything on FT-8.  There are a few nodes on my antenna that I just can't overcome.

But keep in mind that JT65 and the other modes in that software are "weak signal" modes.  Not "low power" modes.  While it is always a great idea to use as little as possible there is nothing wrong with adding power to get the contact done.
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Chris DL5NAM

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..and lower signal from TRX into a amp will bring a cleaner signal out. ( here 3 Watt in gives me 2k out )
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NX6D Dave

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This question comes up regularly. The answer from Flex has always been 'no'. Processors in the radio watch voltages and temps and other parameters carefully and will shut down the radio if damage would be done by continuing.
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NX6D Dave

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The cooling fans going to high speed are an indication that the monitoring systems are working. 
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KC2QMA_John

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To my knowledge the 63/65/6700 are 100% duty cycle or close to it. The P.A is designed to be able to cool under full load. That being said if you were to place the radio in a very hot room or in direct sunlight once the PA exceeds the maximum allowed temperature the radio will go into protect mode until it returns to safe temperature.

The new radios have an even better cooling system because of it’s lager heat sinks and lager fans.!
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Tim - W4TME, Customer Experience Manager

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Official Response
60C is 10 degrees under the threshold where the fan starts rotating at high speed.  You're fine.