I’m trying to build a new repeater using 2 x Motorola GM 340 series radios, an M0AQC AllStar Fob and a Raspberry Pi 5.
I’ve got it all connected but the repeater is acting like a simplex node. I can transmit on my handheld and the repeater RX radio opens up and plays the audio but the repeater TX radio only goes into TX once I stop transmitting. It gives a tone then drops TX.
I can use the allmon3 web interface to make the TX radio send the time and toggle the tone test so it must be getting audio from the Pi.
I’ve used asl-menu to set the RX audio and noticed that it only shows that RX audio is being detected for around 3 seconds before the level indicator stops showing.
I am not yet familiar with the Motorola GM340’s but have built repeaters and gateways using various Tait radios. The symptoms sound like a problem with the PTT line or COS. So things to try would be inverting the signalling on the radios GPIO pins. e.g. swap active hi to active low for the pins you have set-up for Voice PTT & PL/DPL detect. This is done with the Motorola CPS software. Make one change at a time then re-test. Another mechanism to troubleshoot will be to check the settings on the Interface Tune CLI. So SSH into the Pi, sudo asl-menu. Select 1 Node Settings > Select 1 AllStar Node Setup Menu > 1 Update Node XXXXX > 8 Interface Tune CLI. Try changing ‘I’ Change Carrier From (currenly ‘usb’) to usb invert. Also try toggling ‘H’ Toggle PTT mode. Do you have a good earth path between all the devices. I am not sure if the M0AQC box handles this.
Tom.
P.S. I have a couple of Motorola GM340’s arriving mid-week to build a repeater but I will be interfacing to a CM108.
Thank you both. The M0AQC fob is basically a CM108 with the modifications done. I’ve had it working on a simplex gateway in the past but can’t get this repeater to behave!
I can now get the repeater to TX when sending a “Say Time of Day (local only)” command via allmon3.
If I use the test handheld, I can here the repeater RX open but the transmitter is not active. If I select option V (View COS, CTCSS and PTT Status) from the Interface Tune CLI then I see the following when the repeater is idle:
Receiver/Transmitter Status Display:
COS | CTCSS | COS | PTT
Input | Input | Out | Out
Clear | Off | Clear | Clear
When I TX with the test handheld I see:
Receiver/Transmitter Status Display:
COS | CTCSS | COS | PTT
Input | Input | Out | Out
Keyed | Off | Keyed | Keyed
However, the COS Input and Output only shows as Keyed for around 2 seconds regardless of how long I hold the PTT for and the TX radio does not actually key until I stop transmitting from the handheld. If I keep transmitting on the handheld doe more than 8 seconds, the PTT Out changes to Clear and the TX radio in the repeater does not activate at all.
If I am quick, I can send *70 on the handheld and the repeater will TX the status message if I drop the input from the handheld within a few seconds.
'As well as the duplex = 2 under the ‘node main’ stanza, is there another general declaration near to the top of rpt.conf. Does it also have duplex = 2. However, I still think it is a problem with the signals on either PTT or COS being the wrong way around. Inverted.
Yes, duplex = 2 does appear near the top in rpt.conf.
I have tried setting PTT and Carrier Detect to both High and Low in the radio config and both USB and USBInvert in the AllStar settings. With any other combination I get no better results.
Would I be better off ordering a DMK URI if I want this to work and be reliable?
Test the logic at the radio to see what is required, (apply signal manually)
Then test the logic at the URI to see what it is actually at.
As I said, you may need to do a electrical inversion.
Most PTT’s are 0v inactive and switch to ground when active. Not all.
So, I can’t speak to your radio’s and a test is warranted.
And it may be sinking more current than can be supplied. So a buffer transistor may be required or a electrical inversion of the logic…
I have had to use a diode occasionally on the COS line. Usually a BAT43. But I guess the M0AQC fob should be plug and play. Are there any settings that can be changed on the fob?
The Motorola GM340 needs the PTT grounded to activate TX. I have tested this by shorting the PTT pin to ground and that works fine.
There is a small pot inside the M0AQC device which I would guess is for audio level.
Interestingly, I have just loaded Hamvoip onto a different Pi and connected it to the same interface. The repeater now works like a repeater but it does not sent a ct at the end of a transmission and does not respond to any DTMF commands. It does show as registered on the AllStar dashboard.
The settings in Hamvoip are:
PTT Mode (currently active LOW)
COSFROM Mode (currently "usbinvert")
The TX radio is set to:
Voice PTT Active Low
The RX radio is set to:
Carrier Detect Active Low
The same settings in ASL3 yield the previous results when the repeater acts like a simplex gateway but does seem to receive commands from the network.
A step forward. I’m now using ASL3 and have RF repeat working. No PTT from the network but if I send *70 via a handheld, drop the TX and then TX from the handheld again I can hear the status audio in the background so it seems to be talking with the network and sending/receiving commands but is not activating the TX.
My 2 * Motorola GM340’s should arrive in the next day or so. At that point I will fully engage in the battle. You mention that COS is not reverting back to clear. You could try changing some of the timers to see if they correspond with the delays you are noticing.
One thing to be careful with. Some radios requirements in terms of PTT/COS hi/lo can compromise the AllStar network/hub that you are connected to. e.g. If the radio loses power, the connected but still powered RPi mght think it is receiving an RF signal or that the PTT is being keyed. It could then be responsible for keeping the network/hub link active with no audio. Then the only thing to look forward to is a ban on the node from connecting anytime soon.
I’ve just ordered a RIM-Maxtrac-RM to experiment with which seemed like a good, low cost replacement for the M0AQC box. It will take a while to get to me but may prove to be more reliable.