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« Last post by ha3flt on 2025-09-06, 16:41:44 »
Hi,
After gaining experience in using one remote system and now building another one, I thought I knew the RRC boxes quite well, but it wasn't true, hi.
These are the USB RTS and USB DTR functions. They operate deterministically, I can turn them on and off from a terminal program during testing. However, they aren't independent of each other. (I use the same virtual COM port for the CAT communication and the hansdhake lines, but I tried setting them up differently with no success.)
The DTR (CW keying) works just fine. The virtual high level on the virtual COM port activates the CW keying, and produces an output on the radio. Low level: back to receiving. (The radio automatically switches between TX/RX, PTT is not needed.)
The RTS line behaves differently, and there is absolutely no mention of this behavior in the documentation. As it turned out, this is the second completely independent remote system that works this way (everything, including the control and radio RRC pairs, is completely different.)
Specifically: it appears that the inner PTT line (measured on the jumper inside the radio RRC box) does not change to high or low, if the USB DTR is _not_ on the logic high level. However, when the PTT is pressed on the microphone connected to the same control RRC box, the PTT on the radio side is instantly turned on.
Unfortunately, we are having trouble with this second remote setup because its transceiver cannot be switched to transmit by the CW keying line in USB Mode as it could with the PTT line. This radio sends the carrier signal also in USB, just as it does in CW mode, so using the PTT, the RTS line is a must.
This is the only way the PTT can be activated by the USB RTS:
1. “USB DTR” on - this is the CW keying line, keying starts
2. “USB RTS” on - now, only at this point, the PTT line in the radio RRC box is activated
3. “USB DTR” off - now the CW keying is off, the radio can be used for USB, etc.
...
4. “USB DTR” on - CW keying starts
5. “USB RTS” off - now, only at this point, the PTT line in the radio RRC box is deactivated
6. “USB DTR” off - now the CW keying is off, the radio can be used for USB, etc.
Without USB DTR, the PTT line won't follow the USB RTS. I haven't found any settings in the RRC boxes that might affect this.
So, what could be the problem? Is it the USB-serial chip inside the RRC or the firmware? Am I the only one with this seemingly deep problem? Do people use the USB line to connect their PCs to the control RRC box at all?
One possible solution is to use a USB--RS-232 adapter solely for the DTR and RTS lines as a second virtual COM port. Having a 4-port HUB built in the control RRC box, this solution is anyhing but elegant. Furthermore, I would need to build two open collector switches to place between the serial adapter and the RRC's PTT and CW lines, hi.
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