The 12v QDX HB that I ordered pre-built arrived Monday the 23rd of Dec. It is replacing the rev. 5 QDX HB that I bought pre-built in May '23 that has developed an aversion to heat - it stops TX after it gets warm. I think a SMT component is lifting as nothing seems to be an issue otherwise (Jeff Moore looked at it three times).
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I tested the new one into the dummy load at 11 volts (how I operate these) and confirmed nice power out on all bands with 3.7 watts on 10 meters via "tune". On FT8 into an antenna at an SWR of 1:1.2 I was seeing 3.4 watts out. It worked fine for two hours the first afternoon and another hour the next afternoon when I noticed the power out rose to 4.0 then dropped to 3.8 on one CQ call.
On the next cycle the magic smoke escaped, JTDX offered to reconfigure because the radio had disappeared, and I saw that the QDX was drawing the max of 1 amp at 5 volts from the Drok buck/booster supply.?
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I cannot see what burned nor where the smoke came from. I can smell the smoke stronger on the top of the board than on the bottom this morning. I tested the Drok with the QDX LB and it is working fine. I then connected the smoked QDX HB to the Drok and it again hit the amps limit of 1 and volts dropped to 5.?
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I am rather disappointed in the three hour life of this new QDX and don't know where to start looking for the short/fault - source of the smoke. I submitted a support ticket today, but hope no one is reading them now!
