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#qdx
#qdx
I built a QDX rev 5 unit and it worked well - around 4 watts all bands.? Then the BS170 fried with lots of sparks indicating it likely touched the heat sink below (I had the case open and saw the sparks) components around got very hot. After their removal the unit does correctly power up and connect using the console. TheTest Cat option passed with a green and I can connect using Putty to the unit. The current draw is 210ma and I found??audio sweep and RF sweep showed all bands? with a -80 to -100 db - so both receiver an transmitter in trouble.
Any ideas on how to proceed? I? noted some users replaced the IC5 - any point here? Thanks in advance! Mike Heward |
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Re: QDX - No transmit. Bad IC5 out of the box?
#qdx
#troubleshooting
¿ªÔÆÌåÓýWall-warts are notorious for being unregulated.? They typically expect a certain load to lug them down, and if the actual load is less the voltage will be much higher.? A few weeks ago I dug through my collection of 12 volt labeled wall-warts trying to find one that was decent ... most ran about 18 volts or more unloaded, and out of about 8 of them only one was near 12 volts. 73, Dave? AB7E On 2/15/2023 6:46 PM, Paul WB6CXC
(tech-blog: wb6cxc.com) wrote:
I managed to burn up the QDX output stage yesterday.? It had been working fine for days with a 9V bench supply, into a dipole (20 meters) with an SWR around 1.5:1.? Then I reconfigured it, moving the QDX from a PC to the little Quadra computer, and using a wall-wart supply that put out about 12.5V.? It worked great -- until it didn't.? At least one of the output FETs developed a drain-to-gate short, cracking the TO-92 case.? This put 12V on the gate, which means that the gate driver (IC5) saw 12V on the output -- this is a 3.3V part.? Fortunately, IC5 self-destructed before it could put much current (and voltage) onto the boards 3.3V supply, so the receive function and everything else I can test seems good.? I ordered replacements for IC5 and the FETs from DigiKey, so next week I should be able to see if I got away as cheaply as I think I did. |
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Re: QDX - No transmit. Bad IC5 out of the box?
#qdx
#troubleshooting
I managed to burn up the QDX output stage yesterday.? It had been working fine for days with a 9V bench supply, into a dipole (20 meters) with an SWR around 1.5:1.? Then I reconfigured it, moving the QDX from a PC to the little Quadra computer, and using a wall-wart supply that put out about 12.5V.? It worked great -- until it didn't.? At least one of the output FETs developed a drain-to-gate short, cracking the TO-92 case.? This put 12V on the gate, which means that the gate driver (IC5) saw 12V on the output -- this is a 3.3V part.? Fortunately, IC5 self-destructed before it could put much current (and voltage) onto the boards 3.3V supply, so the receive function and everything else I can test seems good.? I ordered replacements for IC5 and the FETs from DigiKey, so next week I should be able to see if I got away as cheaply as I think I did.
Yes, Hans, you told me so! -- Paul Elliott - WB6CXC |
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Re: 4.3 Power output vs supply voltage for QDX-HB ???
#qdx
My QDX was seeing the low TX on 10m, so I took Hans advice and removed 2 turns from L10, and cut back the PIN bias to 5ma on 12m and 11m.? Output now is:
12m - 3.6 W 10m - 4.2 W (vice 2.6 W previously) My question now is, can I apply the same logic to 17/15m?? My current output is: 17m - 2.29 W 15m - 2.77 W By pinching the windings on L3, I could get 17m up to about to 3.5 W, but 15m went down to 1.3 W.? Would removing a turn or two from L8 help? Tom/W5VS |
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Re: QRP 50 W amp Problem on Q3 and Q5
#50w
Hi Timo,
To start with, the first picture has the G and S pad labels reversed.? (assuming that G is the gate and S is the source)? The second picture looks OK. You say that the amp blew on startup.? Was that on first applying power or when setting the bias??? Are you sure you are not feeding more than 5 volts to the PTT jack? The pictures are too blurry to see if there are any whiskers or solder bridges.? I would suggest another detailed inspection for any possible shorts.? You could also try reflowing all of the inductors and transformer solder connections. 73 Evan AC9TU |
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QRP 50 W amp Problem on Q3 and Q5
#50w
HI All,
Picked up a strange to me phenomenon on a 50w amp build today.? I have build 3 50w amps previously that are happily doing there thing and never had any issues with any of them.? Amp 4, however blew Q5 on startup.? I replaced the bs170 (q5) thinking it was just a bad component, but after a few seconds the new one overheated and transformed into a resistor, helping q6 become a resistor as well - not good. After some testing, I removed q5, q3, q6 and q4 and found the issue to be on Q3.? The attached pic's are Q3 from the front and the back of the board.? On q3, Source and Drain are shorted.? For the life of me, I can not see how that could be (except if it should be like that).? None of the other mosfets (q5, 4 and 6) have their S and D's shorted.?? Chaps, any suggestions of what this possible could be?? The board is fully populated bar the few mosfet's that I took out, and I rechecked every component again for correct placement. 73 Timo ZR6TM?? |
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Re: Ultimate LPF board - 12 Volt power
Chuck, there are no other boxes or external power connectors -??I believe I'm doing something completely different than you are.
The 10Watt Linear, switched Low Pass filter and the rest of the transceiver components are all in the same box. It's just always been a nuisance that the QRP Labs modules don't both use the same power specification - especially because almost no new designs use 5 Volt logic. I'm installing a newly designed system control board and would like to clear this up once and for all. M |
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Re: Low Power on QCX 50w Amp
I have the Hardrock 50 amp+tuner, it is a great amp and don't discount Jim Veatch WA2EUJ's great support.??
My kit had no firmware installed on the microprocessor, and rather than have to send it back Jim took the time to give me complete instructions to do the installation and it worked great. Highly recommended. 73, Don N2VGU |
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Re: #ProgRock2 update
#progrock2
Hi Willie QLG2 is a natural choice for providing the accurate 1pps for GPS discipline. But of course any other GPS having 1pps output could also be used.? To be clear, the viscometer remained in the uni tribology lab. But what I found was the interface board which I used to plug into the back of my ZX Spectrum to download the assembled Z80 code into the viscometer. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl -------- Original message -------- From: William Smith <w_smith@...> Date: Wed, Feb 15, 2023, 11:20 PM To: [email protected] Subject: Re: [QRPLabs] #ProgRock2 update
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Re: #ProgRock2 update
#progrock2
¿ªÔÆÌåÓýWow, Hans, you sure keep busy, thanks again for sharing your journey with us.
Is the simplest GPS discipline done with???
Amazing as always! And once again, there's a QRP-Labs product that I don't _need_, but I certainly _want_. ? 73, Willie N1JBJ |
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Re: QCX WARC Party - February 2023
>>I am sure a lot of QCX rigs have never been assembled or did not work and now lie in a remote corner.? For mine fortunately I have a colleque >>here who always fixes them again and has built my multiband QCX. Nevertheless my first QCX for 20 m has some strnge bugs and is out of >>service.
Hi Martin, I have built QCX originals for 40 and 20m and also QCX+ for 40, 30 and 20m and all have worked well. The 40m QCX+ has been a real work horse over the last few years. All are used with QRP-LABS 50w amps. The only odd thing I found was the 20m QCX+. Even when attached to a resonant dipole I had RF feedback which gave strange audio and side tone effects. The dipole had a 1:1 choke at the feed point as well.? I had to do a bit of fiddling with RF chokes on the cables to the 20m QCX+ and then it worked O.K.? Don't know if this is the problem you are seeing. Reg?????????????????????? G4NFR |
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Re: U3S Power Jack
What specs are you looking for?
If you are talking about the U3S board that comes as the kit, then the 4 pins of the header are PA, 5V, Heat Ground (starting nearest Q3) . This give a lot of flexibility to power the electronics (5V) and the amp (PA) sections separately. If you are referring to the U3S case kit, it may have been left unlisted so that QRP-Labs could supply what is available.?? I am pretty sure mine came with 5.5x2.1 jack and connector.? I know I replaced mine with a 5.5x2.1 "locking" connector. I never had a problem with the supplied U3S connector, but have with other equipment when used in the field. I just like to know? that it won't pull out when I move the radio. BTW: If you want to feed the PA with a different voltage separately, then you will need to either use a 3-pin connector, or have voltage regulation inside the case. ? ? ? ? ?I found the 5V PA worked just fine for my setup (WSPR). I hope this is what you were looking fro. ------- Rob KB8RCO |
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#ProgRock2 update
#progrock2
Hi all http://qrp-labs.com/progrock2 ? completed final firmware and testing and I'm pleased to say we'll begin shipping the 110+ ProgRock2 pre-orders tomorrow. Apologies that it is later than my estimated end-January due to several production problems, Chinese New Year and my own 2 week family vacation a couple of weeks ago.? This evening I built a test jig, which ProgRock2 slots into, for flashing the bootloader and firmware, connecting a USB terminal and testing. Searching through my junk box for inspiration, I found an old-school PCB card rack 0.1-inch pitch edge connector, which I last used in 1993 to download Z80 code into my final year physics university degree project http://hanssummers.com/viscometer . Brief nostalgia over this edge connector on a little matrix board interface I'd built for my Sinclair ZX Spectrum code development platform, practically museum piece, was quickly overcome by the need for a convenient way to flash and test 500 ProgRock2 boards ;-)? Hence the test jig (see attached photo). ProgRock2 boards just slot in effortlessly, so neat.? Anyway - programming ProgRock2 has been quite a challenge. The original ProgRock was OK to about 1Hz at 10MHz but several people had requested better on ProgRock2. The chosen low end STM32 processor has 22K available for the ProgRock2 application (10K for the bootloader). No hardware floating point unit. Compiling in anything with floating point made the code too big. So while ? could use the techniques for axxurate frequency that I developed for QDX, it was a lot more difficult... Furthermore QDX doesn't have GPS discipline and it doesn't have absolutely high frequency accuracy on the USB dial frequency, but it DOES have extremely precise tone shift frequencies since firmware 1_06 released in Dec 2022. Anyway after a lot of head scratching and hair pulling I think I have managed it pretty well. I'm lacking extremely precise frequency measurement tools but I know some of you will put it through rigorous tests and I'll look forward to the results.? Theoretically I believe the setting resolution and GPS discipline step is equivalent to about 0.0005 Hz at 10MHz, in other words 0.05 ppb (parts per billion). That's more than 1,000 times better than the previous ProgRock. The 25MHz is the same TCXO used in QDX so it's already very stable. I implemented a configurable dual control loop for the GPS discipline, the secondary loop ensures that the long term frequency error accumulates tends to precisely zero. Configuration is by connecting a terminal emulator via the onboard micro-USB connector. As original ProgRock, you have three digital control outputs allowing selection of 1 of 8 banks of the three Si5351A output frequencies. Quadrature and antiophase clock generation are also supported (clock 1 can be 0¡ã, 90¡ã,180¡ã or 270¡ã phase offset from clock 0). For future firmware updates I'm already thinking of adding CAT control for example. The best thing about ProgRock2 is the firmware update procedure, which will make it easy and free to roll out firmware updates to all owners (USB Flash memory stick emulation, same as on QDX, QLG2, U4B). Documentation will follow on the website in the next day or two. And I do have to entertain myself by using an old HC6 crystal can as an enclsosure for a ProgRock2. Because it's *that* small. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl |
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Re: QCX+ Reciever audio fades out to zero seconds after startup
Was this fault resolved? I have something very similar. It was mostly working ok but I did have a problem that caused me to replace IC8. After this I lost the display with just the backlight working but did notice when I had the headphones plugged in the receiver faded to zero within a second or two.
All the bias voltages are about double (ics 5 to 8) and the voltage starts to rise on them too. The regulator has also started getting pretty hot which it wasn't before. IC1 not giving any o/p on the scope. The only thing that seems to be running is the 27Mhz from Xtal2.? Have checked IC8 for problems but not shorting anywhere that I can see. Have checked with magnified headset but no shorts found. Any suggestions would be gratefully received. Have a scope etc but not much help at the moment. Thanks? Mike G4TSQ |
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Re: Low Power on QCX 50w Amp
George,
You are correct about the WA2EBY amp kits.? The last supplier discontinued the kit (AmateurRadioKits.in).? He may bring it back at some point. The club that I was a member of raves about the HardRock50 amp.? If you are willing to spend the extra money, it appears to be a solid performer.? There is also a built-in ATU that can be added. 73 Evan AC9TU |
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Re: Low Power on QCX 50w Amp
Evan
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Re: Low Power on QCX 50w Amp
George,
I am glad that it helped.? It still seems that the power is lower than expected, though I have only built one of these amps (the other is still in a box for spare parts).? As stated before, I switched to a multiband WA2EBY amp when it became available. You could increase the bias a little more (say 10ma) to see if the power increases again.? This will depend on where you will be using the amp.? For battery power portable operation, it may be better to keep the bias lower to get better efficiency. Have fun with the new toy! 73 Evan AC9TU |
Donald S Brant Jr
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