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Author Topic: Dx-70 problem  (Read 2273 times)
K5TEB
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Posts: 45




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« on: November 22, 2011, 05:05:28 PM »

Greetings to y'all,
   I have an Alinco Dx-70 that I am  powering with a deep cycle marine battery.  This afternoon after working a Ja station I noticed that the rear of the rig was not warm but hot.  I disconnected everything quickly.  No smoke or burnt wire smell noticed.  Any ideas as to cause and what I can do to prevent this again?   73 de k5teb ex kd5sbo, Terry.
   PS:  A very Happy Thanksgiving to you all.  TLV
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KB4QAA
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« Reply #1 on: November 22, 2011, 09:39:30 PM »

Were you transmitting on high power?  Talking for a long time?   Or was this typical operations for you?

Many HT's can get pretty hot quickly on high power
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K5TEB
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« Reply #2 on: November 22, 2011, 10:11:02 PM »

QAA,
  Thanks for your reply.  I was transmitting at 100 watts on 15 meters.  I checked and then re- checked my connections for antenna tuner,  rechecked swr.  No loose connections and swr was 1.5 :1.   
   I wonder if a couple of computer fans blowing into the rear of the rig would help.  I have several and a couple of 7aH batteries.  This is a puzzlement.
                                  73 de k5teb,  Terry
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K2DC
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« Reply #3 on: November 22, 2011, 11:59:10 PM »

Terry,

   Just my opinion, butI'm not sure it's a puzzelment at all.  Most HF rigs operate at less than 50% efficiency, meaning every watt transmitted (average power) creates at least a watt of heat.  If the rig was warm but not hot, I don't think I'd be too concerned.  If you'd like to add a fan on the back it would certainly keep things a little cooler.  But without it, I don't think you're doing anything harmfull to the rig.  I'd also bet that this is the first time you felt the back of the rig after a long session.

73,

Don, K2DC
 
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AC4RD
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« Reply #4 on: November 23, 2011, 04:07:42 AM »

For a lot of small modern radios, "warm but not hot" is perfectly normal.  You might keep an eye on it to make sure it doesn't get hot, and a small fan might help, but it's probably 95% likely that this is perfectly normal.   Keep monitoring it, but don't let that get in the way of enjoying the good propagation!  :-) 
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AE4RV
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« Reply #5 on: November 23, 2011, 05:02:29 AM »

"not warm but hot"

Possibly normal but you should ask other owners about their rigs.
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K5TEB
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Posts: 45




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« Reply #6 on: November 23, 2011, 07:22:12 AM »

  Thanks to  all who replied.  I have cobbled together a fan for the rig and keep an eye on the temp.  Thanks again and Happy Thanksgiving.
                               k5teb, Terry
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K8AXW
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« Reply #7 on: November 23, 2011, 08:55:19 AM »

I'm wondering if there is any difference in operating temperature if you would switch to a standard 13.8V power supply?
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K5TEB
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Posts: 45




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« Reply #8 on: November 23, 2011, 02:11:15 PM »

AXW,
  I was wondering the same thing.  I'll order one tonight off the net.  Thanks for the suggestion
                              Tks es 73 de k5teb, Terry.
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KG6BRG
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« Reply #9 on: November 24, 2011, 05:56:41 AM »

What about the dx 70's internal fan, was it running? It should have been going full speed, and after you un-keyed for a time too.  Check the fan for proper operation.  Good luck.  Scott.
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K5TEB
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« Reply #10 on: November 24, 2011, 08:24:56 AM »

Scott,
  Thanks for your reply.   The fan should have been the first thing I checked.  However, old age and brain damage being what it is I never even thought about it.  Will check the fan in a bit and will let you know what I find.   Happy Thanksgiving to all.  k5teb, Terry.
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KG6BRG
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« Reply #11 on: November 24, 2011, 09:16:02 AM »

Just for reference Terry, my dx-70 at 100 watts SSB will run warm to a bit warmer, but the internal fan will run at hi speed while in QSO AND run a bit longer in RX to cool the heat sink. 
In summary, quite warm at 100 watts with fan a full speed. Cools down quickly when QSO is over, fan runs a bit longer.  Cheers, Scott.
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