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Yes, that would certainly work, but I needed to be able to turn off the power completely by remote control (this was so that I could switch to using an SDR receiver instead of the QDX over the USB

More later. Multi-year class reunion inside my old high school today Dublin High School, VA ( Dukes ) Class of '70 here. Lettered in varsity track- can only walk fast these days. 73, Bill, N4QA

Sorry again, quicky fingers on a mobile phone... Hi. Just wanted to conclude that's why I prefer an active 0 Ohm PTT (inactive = open circuit) instead of an active +5V PTT (inactive = 0V).? QDX is

... just to add... The reason for the 100R parallel to 470R is actually the PTT input in the 50W PA, which is over 470R and a red LED in series tied to the GND.? This way those +5V from the QDX is no

Hi, This is what I have done to get the reliable PTT trigering of a 50W PA from the QDX.? The reason is that the QCX's PTT is a direct logic output with either 0V or +5V level whereas the QDX PTT is

I would add using a dummy load to reduce RFI as an issue. 73 Evan AC9TU

Will, Note that the QCX+ rev 1 has the PTT signal on the TIP, and the others, including the QDX, have the PTT on the RING of the 3.5mm jack.? If you are using the same cable as a rev 1 QCX+, then it

Hi Wil. It sounds like something might be loading down the 5 volts. You should find a way to measure that voltage while transmitting with the QDX PTT connected to the amplifier. I recall reading a

Hi Peter, Sorry, what I meant was to use only one Grove MOSFET board, to supply 12V to the QDX when it's on. When that one MOSFET board is off, the QDX is powered by the string of diodes. Put them in

Too keep is short, QDX Rev 3 with the 1.04 firmware is providing 5 volts to the ring of the PTT cable, but not triggering the QRP Labs’ 50w Amp. ? What should I be checking? more details: - ?QDX

Hi Other WIllie, Sorry, I misunderstood, thought it was working on 30M, but on closer reading it turns out it was only for a brief moment, my mistake. OK, now we're into shotgunning the problem: As

Willie.? Yes, you can absolutely operate the switches in series, with the second switch just short circuiting the diode droppers. In that case, you would need to short circuit D3 in both of the Grove

Congrats on getting your QDX back on the air, Alexander! I use the following SWR bridge and tuning indicator with mine so that the max SWR 'shown' to the QDX will be 1:2... A fun and easy kit build

Bill, Did you check using the terminal program as Evan suggested? This would confirm a PC problem (or not). Operation manual section 4.1 PuTTy is available for Windows. 73 Alan G4ZFQ

Hi ya same name ! That's right ! - no rf feedback. I'm confident that my Bird dummy load prevents rf feedback. Also, still getting 2 repetitive blinky LED flashes which, according to the ops manual

Ken Is X6 the answer? The LPF signals are brought out, I thought to do just this sort of thing. 73 Alan G4ZFQ

I know you said there's "no RF Feeedback", but this is classic symptoms of RFI, which can be disconcerting on QDX as even brief transmissions into a mismatched load (which usually causes RFI) can blow

Alexander, Good news! Just want to mention, the diode will drop 0.7V across it in this application. This is the reason the FET is used since it has a lower voltage drop across it. This is will

On second thought, opening QDX probably won't help. Today, I'm on 30m and pwr out is 5 watts with 12 vdc at 750 ma. Power supply steady - no trips nor dips- just short xmsns ! Sure is a mystery !

Hello Al and Evan, thank you both so much for your kind replies and detailed explanations, Q7 was the right guess! Wit Q7 as a search string I greped through the archive and found the other failures