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
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Chris AG6CK
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#108749
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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
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Cliff
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#108748
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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
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Jonathan Burchmore
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#108747
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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
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Tony Scaminaci
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#108746
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Re: QMX - smoke - another C107/Q108 failure
It looks like about 38 seconds or so, if I'm measuring this right.
Jonathan KN6LFB
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Jonathan Burchmore
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#108744
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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.
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Jonathan Burchmore
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#108743
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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
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aa0jr Jakob <aa0jr@...>
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#108741
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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
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Steven Dick, K1RF
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#108740
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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.
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73, Dan? NM3A
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Daniel Walter
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#108739
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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
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Tony Scaminaci
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#108738
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WSJT-X results
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73
Karl
KI4ZUQ
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Karl
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#108737
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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
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KK4ITX John
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#108735
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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
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Kees T
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#108734
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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
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Kees T
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#108733
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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
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Jerry Moyer
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#108732
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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
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Evan Hand
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#108731
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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
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Al Holt
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#108730
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Re: QRP antenna tuner?
Picture of a 4sqrp tuner...
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73
Karl
KI4ZUQ
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Karl
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#108729
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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
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Cliff
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#108728
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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@...
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#108727
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