I have already setup multiple ASL nodes with cm108 sound fob. I always use usbinvert pulled down by 2n2222 transistor. Everything was fine until I ordered 10 new cm108 (3usd each) from an online store where I ordered my previous soundcards.
The problem with the new sets of cm108 is that pin 48 keep of being triggered even if I disconnect it to the transistor. I removed everything that is connected to pin 48 and still the allmom dashboard keep on showing local souce being triggered. I tried pulling it up with 5V of the soundcard but the problem still exist.
The problem occured with the new set of cm108 cards.I orderd 10 more cards and the problem still exists. Does anyone here experience the same issue from these cheap CM108 soundcards?
Hi,
I have always included a small diode in line with the COS on my 888 nodes never needed a transistor.
Found this image to show the diode connection.
Hope this may help.
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Yes I also put a diode inline to pin 48. Still getting this issue.
Hi,
Have you looked at the 5v supply with an oscilloscope to see if there are any spikes superimposed?
Also do you have another Raspberry Pi to try?
Try cleaning the sound fob edge connector they are notorious for being tarnished and producing intermittent connection causing all sorts of problems.
Martin
Hello,
I don’t have oscilloscope. I will try switching to usb and not usbinvert then switch a little bit of my circuit. Hoping that it will fix the issue.
Hi! I also ordered these aliexpress fobs and its my first time so it has been really frustrating.
usbinvert causes my tx to also show up as tansmit local source but when I change it to usb it is ok then. Try usb, it should stop that if we have the same fobs. I have modified the fobs with regular components as shown on How to Modify A CM108 Sound Fob For Allstar. - allstar setup.com .
Are you able to receive and transmit? Try using setting carrier to usb instead of invert, or copy my simpleusb settings from UV82 and CM108 wont release PTT - #18 by ap2x
I am facing an issue where my TX doesnt stop after it transmits expected response. Do you get the same problem by using my settings?
My setup is baofeng uv82, cm108 fob, ASL3 on debian
Hi,
These are the settings I use on my constructed Baofeng 888 node.
I have enabled CTCSS in the Baofeng 888.
The diode in COS line I found was needed 1N4148 or similar.
Martin
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Hi. I will try usb instead of invert. It was just weird for me since I already able to build more than 10 node interaface with the same circuit board that I built and it was just fine until this new batches of cm108 arrived. I am able to transmit and receive with the current setup. Its just that transmit local source keep on triggering.
Thank you for your suggestion.
Let me know how it responds and it would be really helpful to me personally if you could share how you modified your cm108 fob as I am unable to pinpoint whats up with mine.
@Postman Did changing to usb work for you? I ended up adding a 0.01uf ceramic capacitor between C and E on my fob to release PTT as that wouldn’t get released after transmission ended.
My node is working as expected now. I only need to find some shielded wires to get rid of hum when it TXs.
my settings are given below;
hi, I guess the new cheap cm108 does not like usbinvert. I changed my setting to usb, made the circuit simple by adding just 10K resistor from pin40 to ground. Then just connect your positive COS in between that resistor and the pin48.
Everything now works fine.
EDIT:
Suddenly the problem went back. Problematic cards.
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The Masters Communications RA-25 boards are well-priced and “just work” rather than trying to fix odd fob problems: RA-25 Radio Adapter Interface Board - by Masters Communications
I appreciate this.
However, 60USD assembled and tested is a little to high for hams like us who lives in the 3rd world country. We have to resort to low cost solutions.
Could you share what changes you made to the fob? If it is similar to mine, maybe I can help you go through the steps I took to identify the problem.
I found that the settings used by most guides didn’t work for me so I had to test various and finally had one working. I connected my fob to a baofeng UV82. I had to add a 10k resistor to my cos line for it to stop spurious keying.
Hi! I just wanted to share what worked for me at the end. You could give it a try and maybe it will work for you too.
I added a 10k resistor as suggested by @N8EI and I also added a 10nF ceramic capacitor (103) and a 65nF ceramic capacitor (it said 104 which should be 100nF but mine measured 65) between C and E legs on the fob (PTT and Ground legs) which fixed the PTT triggering but there was a hum in audio from the node HT.
Then I added a 10nF capacitor in line with the TX wire. I had soldered a wire to the fob and then I soldered one leg of the capacitor to this wire and the other leg to the wire from the node HT.
Now I have crystal clear audio, both RX and TX with the settings I shared above. Give it a try and definitely let me know if it worked for you as well.
There is another option, you can use an AIOC which does the same as a CM108.
The AIOC when flashed with the correct firmware can be used to simulate a CM108 and connect to a Baofeng and no modifications are needed. Depending on who you buy it from it can cost you $30 to $60 USD.
I have a couple working with Allstar with no problem using a Baofeng UV5R but the 888 will work also.
You can also get them by making your order directly from China and 5 of them will cost you about $100 for 5 of them. They literally make the boards for you and send them after the ensemble is done so you are not paying extra for someone who did the same and is charging you to flash the firmware and solder the leads to the board.
This is the AIOC with 2.5 and 3.5 pigtails so it’s away from the radio. People were having problems with the AIOC being plugged directly into the radio and getting interference from the antenna.
