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Re: QMX: Kit build trouble, a short between A & B for Step 17 of Section 2.9
According to the assembly manual it says "Finally, there should be NO connection between A and B. Hold one probe on any A point and the other probe on a B point. That should read infinite resistance
By Chris AG6CK · #108749 ·
Re: QMX working FB then shorted out. Ideas?
Well, Steven I owe you on this one. You called it right to the component. The short was on the 5V rail and the component was D108. That is sure a tiny little diode. Going to be fun to put a new one
By Cliff · #108748 ·
Re: QMX - smoke - another C107/Q108 failure
It's possible I measured the wrong thing? ?I measured it from what I thought was pin 3 of the 3v3 SMPS board. ?The middle pin on the top. Jonathan KN6LFB
By Jonathan Burchmore · #108747 ·
Re: BS170 Fail
Hi Wayne, To answer question 3… there is a better transistor for replacing the BS170’s - TN0606. The data sheet can be found
By Tony Scaminaci · #108746 ·
Re: QMX - smoke - another C107/Q108 failure
It looks like about 38 seconds or so, if I'm measuring this right. Jonathan KN6LFB
By Jonathan Burchmore · #108744 ·
Re: QMX - smoke - another C107/Q108 failure
Here's a tighter view: And zoomed in on the linear regulator portion. ?Vertical scale in both is 500mV/division with a -1.5V offset. Here's a similar trace with channel two showing LIN_REG_EN.
By Jonathan Burchmore · #108743 ·
Re: QMX substitute for Q103
I don't see why it should not work with the AOD21357. Specs are very similar to the AOD403 and both are well over dimensioned for this purpose. I would try it if I were in your shoes. Experience is
By aa0jr Jakob <aa0jr@...> · #108741 ·
Re: #QMX holy smoke released again, C107 and D108 destroyed #qmx
IF IT FITS and you want to use a premium cap, I would use the Kyocera TPSE477K010R0050 for $2.58 at Digikey, qty 1. It is 470uF 10% tolerance 50 milliohm ESR, Not cheap, but this series is surge
By Steven Dick, K1RF · #108740 ·
Re: BS170 Fail
Or put an absorptive bridge between the QxX and switch it in for tuning, then out to operate. Also don't let the tuner auto tune when it detects a change in SWR. -- 73, Dan? NM3A
By Daniel Walter · #108739 ·
Re: QMX - smoke - another C107/Q108 failure
The 1N4148 diode in series with the linear 3.3V output is a necessary evil to prevent backward current flow once the 3.3V SMPS rail comes up. However, it destabilizes the linear 3.3V rail as noted by
By Tony Scaminaci · #108738 ·
WSJT-X results
-- 73 Karl KI4ZUQ
By Karl · #108737 ·
Re: QRP antenna tuner?
Looks good Karl, does it work good for you? I have one sitting in a box in Florida waiting for my return to assemble it. 4S has some good kits and they have a great organization too. I activated my
By KK4ITX John · #108735 ·
Re: QMX - smoke - another C107/Q108 failure
Jonathan, After turning the power OFF and having the 3.3V VDD drop to 0V, how long does the 5V VCC stay at xxV ? 73 Kees K5BCQ
By Kees T · #108734 ·
Re: QMX - smoke - another C107/Q108 failure
Hello Hans and Jonathan, The plots require some questions to be answered in my mind. 1) What is happening to 3.3V between t=80ms and t=200ms after Power ON ? Need more detail on the actual voltage
By Kees T · #108733 ·
CAT port returns ` ` ` on QCXmini
Just curious if anyone has seen this and might know what's going on.? Using Putty on the CAT port of a QCX-Mini, the QCX returns a (`) with each character typed.? ?For example, if I type FA; and
By Jerry Moyer · #108732 ·
Re: QDX rev 5 Troubleshooting
First, it is considered good form always to post your name and call at the end of a post.? Then, others can direct their posts to the correct person.? Also, when posting in response, direct the post
By Evan Hand · #108731 ·
Re: BS170 Fail
Wayne, Thanks for the reply! Read over other posts here about use of auto-tuners and the Q-Line. In some cases they'll show a momentary high VSWR to your rig. The PA in QCX-QDX-QMX doesn't like too
By Al Holt · #108730 ·
Re: QRP antenna tuner?
Picture of a 4sqrp tuner... -- 73 Karl KI4ZUQ
By Karl · #108729 ·
Re: QMX working FB then shorted out. Ideas?
Steven, Thanks so much for the response. I'll get to it and respond when I know more. I've a lot to learn here. 73, Cliff, AE5ZA
By Cliff · #108728 ·
Re: QDX rev 5 Troubleshooting
Thanks again John and Nick, Managed to get some more PD time. I disconnected the cat on D3 and D6 to see if that told me anything but I don’t think it it did, results below, look like the only
By laycockc+GIO@... · #108727 ·