Searching for PTT in the QCX mini manual gets no hits.? It seems that you need to use a TRS plug, not just a TS plug.? The Ring seems to go from 0 to 5v on key down and follows keying.? Have I got it right? No QCX mini schematic? 73 Don K2BIO
The just-out Rev 3 manual has a good explanation on page 80. Notice the change that has come with Rev 3. It is an improvement and a simple rewiring will make early models consistent.
PTT output
The PTT output is at the ring of the 5V/PTT connector jack. This signal is 0V when the QCX-mini is in Receive mode, and +5V when the QCX-mini is in Transmit mode. If you are connecting the QCX-mini to the companion 50W PA kit, then this signal has to be connected to the 50W PA kit to cause it to switch to Transmit mode. A standard 3.5mm stereo audio cable can be used (having a 3.5mm stereo jack plug on each end).
Note that the pinout of the 5V/PTT connector is not the same as the Rev1/2 QCX+ PCBs. In the QCX+, ring is +5V and tip is PTT. This has the disadvantage that plugging in a cable while the QCX+ is powered, can short the +5V to ground. Another disadvantage is that standard 3.5mm stereo audio cables can¡¯t be used. For this reason, complete compatibility was broken in this instance. If you wish to use a 50W PA kit with either QCX+ or QCX-mini, the QCX+ manual contains details of the very simple modification needed to swap the tip and ring connections in the QCX+.
You can download a PDF here
¡ªMike Perry, WA4MP
On Oct 30, 2021, at 3:42 pm, CW Morse <RadioPrinceGeorge@...> wrote:
Searching for PTT in the QCX mini manual gets no hits. It seems that you need to use a TRS plug, not just a TS plug. The Ring seems to go from 0 to 5v on key down and follows keying. Have I got it right?
All QCX-mini PCB revisions have the same PTT output jack connections with the positive-going PTT signal on the "ring". This is the same as on the 50W PA and a simple standard common stereo audio cable may be used (Dollarstore, Poundland, whatever).?
The explanatory text at page 80 of the manual is also not new and is found also in the manual for PCB Rev 1 and 2 QCX-mini.?
The only kit that had PTT tip and ring swapped, was QCX+ PCB Rev 1 and 2. Rather than live with my design error I chose to correct it in QCX+ PCB Rev 3 and all PCB revisions of QCX-mini.
Therefore other than QCX+ Rev 1 and Rev 2, all other QCX+ and all QCX-mini are the same as the 50W PA.?
-------- Original message -------- From: "Mike Perry, WA4MP" <editor@...> Date: Sat, Oct 30, 2021, 11:54 PM To: [email protected] Subject: Re: [QRPLabs] How does PTT work in QCX mini?
The just-out Rev 3 manual has a good explanation on page 80. Notice the change that has come with Rev 3. It is an improvement and a simple rewiring will make early models consistent.
> PTT output > > The PTT output is at the ring of the 5V/PTT connector jack. This signal is 0V when the QCX-mini is in Receive mode, and +5V when the QCX-mini is in Transmit mode. If you are connecting the QCX-mini to the companion 50W PA kit, then this signal has to be connected to the 50W PA kit to cause it to switch to Transmit mode. A standard 3.5mm stereo audio cable can be used (having a 3.5mm stereo jack plug on each end). > > Note that the pinout of the 5V/PTT connector is not the same as the Rev1/2 QCX+ PCBs. In the QCX+, ring is +5V and tip is PTT. This has the disadvantage that plugging in a cable while the QCX+ is powered, can short the +5V to ground. Another disadvantage is that standard 3.5mm stereo audio cables can¡¯t be used. For this reason, complete compatibility was broken in this instance. If you wish to use a 50W PA kit with either QCX+ or QCX-mini, the QCX+ manual contains details of the very simple modification needed to swap the tip and ring connections in the QCX+.
You can download a PDF here http://qrp-labs.com/qcxmini
¡ªMike Perry, WA4MP
> On Oct 30, 2021, at 3:42 pm, CW Morse <RadioPrinceGeorge@...> wrote: > > Searching for PTT in the QCX mini manual gets no hits.? It seems that you need to use a TRS plug, not just a TS plug.? The Ring seems to go from 0 to 5v on key down and follows keying.? Have I got it right?
Mike Perry, WA4MP