40M QCX problem uponpower up
I finished my 40M QCX today which I built into a QRP Labs enclosure.? Upon power up the display works fine and I did get the rig set to 40 meters in the menu but it is putting out a very loud continuous audio tone which I assume is the built in alignment oscillator tone.? However the tone starts upon power up, not when I enter the alignment menu.? When I go into the alignment menu for BPF I hear another tone which I'm guessing is the real alignment tone.
Any ideas on what is happening? Anyone else have this happen?
73,Bill NZ0T
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Got that! Thirty-three days later. I also got a package from AMSAT-NA 29 days after they mailed it 1st Class USPS from Maryland, USA. Post XMAS our US Postal System appears to have crashed. Except for Amazon deliveries, which are only a few days late..,
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Re: Power output questions
Phil, sounds about right. The best I could get from my QCX 20M version is about 2.1 watts.
Joel
N6ALT
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Re: No Tx Power..using troubleshooting guide
#qcx
Hi Alan,
I am back in business :-))).? The problem was a shorted Q6.? I think I had the problem when I hooked up the GPS, and may have not had a dummy load on it. (I did have to replace one or two of the BS170s, as I recall) But the board is putting out 3.95W with a new MPS751.? I verified by using the on board test equipment (and Tx current).? Seeing that 3.95W reading on the LCD was a very beautiful sight indeed.? :-))))
Thank you so much for all? your help and helping me use the very good troubleshooting guide.? ?I appreciate it very much.?
73 Kent KC9LIF
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Hi Mario,
Thank's for the information.
I always think twice before I suggest replacing a part where you
cant prove it's faulty by some means,
but I think? you may be at that point.
(You are 101% sure!)
The power supply is stable and noise free?
No switching or 'Buck' convertors anywhere?
(A recent innovation is a drop in replacement for the 'old' linear
78 series of voltage regulators that now employ? DC/DC switching
technology,
which I would avoid using in this application)
Regardless can you just temporary power the unit from another stable
5v supply?
Also if not already present, can I suggest a >4700uF capacitor be
placed on or close to the 0v & 5v input pins of the U3 PCB.
I ask because, the display while in the fault condition
doesn't have a classic look of just an address / data line failing,
more like the driver IC on the LCD module.
However it cant be, You state this is now the second display that
exhibits this identical fault....
Have you, or know of anyone local who also has a second U3 to
exchange first the LCD module and see if the fault carries over?
Have you ever tried reusing the 'faulty' LCD in another project, I
don't suppose you also have interests for instance arduino's etc?
(Just to see if the LCD displays are permanently damaged or just
being instructed to display the incorrect display?)
Failing that it's looking like the next step is to change IC1 MCU
after all? this drives the LCD....
regards Alan
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Hi Alan.
here some picture/video to show the display.
Answer to your questions:
I changed exactly the same LCD-module, wich runs certain days
perfect, but then the same behavior,
and still the US3 works perfect on all bands!
I am using a clear (measured) 5.06V PS.?
I checked the ?contacts between PCB-display OK.
The display-problem is permanent. The whole unit is in the
original screened enclosure.
I measured the voltage ?at the LCD-pins with 5V.
Thanks for your help
Mario
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Re: QCX high current first start up;
Alan,
4.9K after D3. Disconnecting L4 does not do the trick.
John, This is puzzling, 2 amps will not pass through much without instantly blowing it. 4.9K means it is not directly shorted but going through a component. Are IC5, 6, 7, 8, 9, 10 the correct way round? 73 Alan G4ZFQ
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Re: Testing replaced transistors
Hi Jess,
Glad your QCX is working.
Cheap transistors etc from china are a gamble if they are up to
specification and even if they are actually the device they are?
labelled as.
When something is TOO good to be true, it probably is....
But those component testers have their place.
They are a good buy, I used one daily and always correctly
identified devices as go / no-go.
Quicker and less likely to make measurement errors than using a DVM.
Just remember if measuring large value electrolytic's to discharge
them first, before testing.? =-O
Not a mute point at all.
They're a useful addition in the toolbox for any home constructor.
Regards Alan
On 05/02/2018 03:13, Jess Gypin wrote:
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Kind of moot point but...
I bought one of the cheap RLC 328 testers on Ebay. Not
hoping for much I stuck in some caps and coils. Measured them
to within 1-2% of the value. Hummmm...Tested diodes and
transistors and FETS. Tested them all correctly. So I stuck in
the transistors that I took out when Q6 was shorted. It tested
as two low resistance resistors. Tested the BS170 finals. They
tested as two low value resistors as well. SO they were blown.
Stuck in one of the good ones and they tested as good. So, not
sure if that is worth anything but at least I did not change
good parts. My QCX 40 should be here soon on its way back from
Hans and I am looking forward to finally using it on the air.
My QCX 20 shipped a couple of days ago so I hope that I have
better luck building that one. At least I have a LOT more
experience with trouble shooting and knowing how the circuit
works! :)
Jess AE0CW
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Re: QCX high current first start up;
Alan,
4.9K after D3. Disconnecting L4 does not do the trick.
(I found a cap not soldered one side, but fixing this did nothing of course.)
John K1ym
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On Feb 5, 2018, at 6:28 AM, Alan G4ZFQ <alan4alan@...> wrote:
Thanks Alan. You are probably right. I tried that. The 12v line is not a dead short. It measures ~5K. Something is drawing current. The 7405 is putting out 5v. John,
5K After D3 polarity protector?
If so then it could be something other than a whisker. The 7805 will not take 2A.
Is it possible that it went into TX mode without a dummy load? If this is possible try disconnecting one end of L4 and briefly see if the high current condition is still present.
If this should stop the high current condition then Q1, 2, 3, and Q6 would need to be replaced.
73 Alan G4ZFQ
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Hi, sorry, I just saw that this thread had been updated.
Yes, the box design is from Thingiverse. If you need the stl file for ? QCX 20m ? I can make one, no problem.
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.eep and .hex file qustion
Chris Wilson 05 February 2018
The current U3S firmware is 3.12a nd comprises just a hex file, no
.eep file. If I load V3.12a hex file onto a new Atmega chip it will
not have any of my settings. To copy a file *WITH* my settings do I
just read a ready set up chip as a different .hex file and load that
onto a new chip? I am confused about the use of the .eep file info.
Is that the correct way to write a new chip with 3.12a *AND* my
current set up stuff?
Thanks.
--
2E0ILY
Best regards,
Chris mailto:chris@...
--
Best regards, Chris Wilson (2E0ILY)
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Re: #qcx Portable operation
#qcx
Hi Olaf,
I did not check the Tx on a spectrumanalyser (yet) , but I did check the tone on another receiver. Tuning up and down showed nothing different.?On Rx there is no difference in received noise level when compared to a good linear powersupply. I did however put ferrite rings on both the input and the output leads as a common mode filter. The QCX is in a metal Hammond enclosure with an LC filter at the power input to make sure it is all clean, while the boostconverter is outside the enclosure at the battery.
73 Martien PA4H
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Re: #qcx Portable operation
#qcx
On Mon, Feb 5, 2018 at 12:30 am, MartienPA4H wrote:
Had no extra noise from this unit but I did put some ferrite rings on the leads just to be sure.
Hi Martien, running 1..3? high capacity Lithium cells in combination with? a? up converter seems to be quit attractive? ..? good to hear that you have no extra noise noted.? ? Wonder if you also check the transmit signal for extra 'AM' Sidebands that might be caused by the? switching? ripple? ? Did anyone try to use the? up converter only for TX? , maybe with variable output voltage as a simple? way to control the TX output for example for more save antenna tuning/test ? ? Running 4? Lithium Cells? in a 2 + 2 pack may be also a idea.. ? so you can run the batts in series for 'High Power' and in parallel for 'tuning'? and charging? even with very low cost chargers.? ? ? 73 de Olaf /DL5YBZ
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After assembling everything we`ve now trouble with 3 kits. The system starts correct, the GPS-modul works fine and the heart is pulsing in the display. The system switches to TX ?(WSPR) and we can hear the transmission in the separate receiver. The TX QRG is correct but we get no report at wspr.org Steve, You are sure the frequency is exactly correct? The default GPS configuration takes a long time to adjust it. On what bands? Little-used bands may not have a spotter within range. 73 Alan G4ZFQ
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Re: QCX high current first start up;
Thanks Alan. You are probably right. I tried that. The 12v line is not a dead short. It measures ~5K. Something is drawing current. The 7405 is putting out 5v.
John, 5K After D3 polarity protector? If so then it could be something other than a whisker. The 7805 will not take 2A. Is it possible that it went into TX mode without a dummy load? If this is possible try disconnecting one end of L4 and briefly see if the high current condition is still present. If this should stop the high current condition then Q1, 2, 3, and Q6 would need to be replaced. 73 Alan G4ZFQ
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Re: QCX high current first start up;
Thanks Alan. You are probably right. I tried that. The 12v line is not a dead short. It measures ~5K. Something is drawing current. The 7405 is putting out 5v.
John k1ym
Sent from my iPhone X
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On Feb 5, 2018, at 2:57 AM, Alan G4ZFQ <alan4alan@...> wrote: I am getting current drain of over 2 amps when I connect 12 v. I see that is not correct.
I noticed I had touched Q3 with my soldering iron during construction and it was slightly melted. I removed it but that was not the problem.
Anything else I can try? John,
It seems likely that an ohmmeter will find a short circuit to ground on the 12V line.
Maybe a whisker of solder, look carefully.
73 Alan G4ZFQ
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Re: #qcx Portable operation
#qcx
Guys,
Thanks for the suggestions. I don¡¯t intend to operate from batteries whilst charging, I¡¯ll just make up a couple of battery packs for portable use, when one gets tired I¡¯ll swap them over.?
I¡¯ll keep the group informed about developments.
73 from Hungary,
Steve G0XAR
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Re: #qcx Portable operation
#qcx
I have also used a similar module with some success.? I published a small inline enclosure here..?
73,
Dave
On Monday, 5 February 2018, 8:30, MartienPA4H <m.rijssemus2@...> wrote:
Hi Steve,?
I use a low cost?Lithium Ion pack. Now these batteries are usually not 13,8V, more like 12,2V and when you transmit even a little less.
That has a negative effect on your output (mine dropped down to about 2,5 Watt). So I used one of these real inexpensive LM2577 step up converters (3,95 euro....).
I aligned it to 13,8V and?4 Watt output. Beauty is that the voltage will stay 13,8V even if the battery is going down a bit. Had no extra noise from this unit but I did put some ferrite rings on the leads just to be sure.
I used this one , but you can find them all over the web???
Please check with your airline what you are allowed to pack. I found out that most airlines limit a Lithuim pack to 100Wh
73's
Martien PA4H
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Re: #qcx Portable operation
#qcx
Hi Steve,?
I use a low cost?Lithium Ion pack. Now these batteries are usually not 13,8V, more like 12,2V and when you transmit even a little less.
That has a negative effect on your output (mine dropped down to about 2,5 Watt). So I used one of these real inexpensive LM2577 step up converters (3,95 euro....).
I aligned it to 13,8V and?4 Watt output. Beauty is that the voltage will stay 13,8V even if the battery is going down a bit. Had no extra noise from this unit but I did put some ferrite rings on the leads just to be sure.
I used this one , but you can find them all over the web???
Please check with your airline what you are allowed to pack. I found out that most airlines limit a Lithuim pack to 100Wh
73's
Martien PA4H
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Re: QCX high current first start up;
I am getting current drain of over 2 amps when I connect 12 v. I see that is not correct.
I noticed I had touched Q3 with my soldering iron during construction and it was slightly melted. I removed it but that was not the problem.
Anything else I can try? John, It seems likely that an ohmmeter will find a short circuit to ground on the 12V line. Maybe a whisker of solder, look carefully. 73 Alan G4ZFQ
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The files are available to anyone.
I printed the short version in black and it is nice case.
I am using CR-10S printer.
Dave
KI7DPP
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Joel Caulkins/N6ALT
Retired Doc
Alan de G1FXB
MartienPA4H
Dave Somers KI7DPP