开云体育

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).

?

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.?

?

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.?

?

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!

The fact thast you've now smoked two radios I would be very concerned about some fault with either the power supply, antenna, swr meter and/or dummy load.

Perhaps, but the two low band QDX's are doing fine with about the same number of hours and using the same antenna, etc. on 20 meters.

Just a hunch...? The BS170s seem to? be the most sensitive, at least to power levels ... maybe heat too. Nothing like FT8 to generate heat.

--

72 de N4REE, Bob Easton - QRP CW forever

I have not heard of a burnt BS170 shorting out and causing high current draw and the radio not booting up. This one no longer has a USB interface - no sound card, no terminal access, nothing.

What really gets me is that I haven't found the source of the smoke. It looks pristine but has a short in the power circuit somewhere.

I bought a pair of used QDX's shortly after I placed the order for this factory built one (LB & HB) and they are both still working great. I don't think it's my station that's killing them.