Hello Tim,
So just to clarify some things: The ICS boards do have two logic inputs per port, a COS input and a CTCSS input which each get their own GPIO pin. The core SVXLink software doesn’t currently have support for a separate CTCSS input, so that is unsupported at this time. CTCSS should be set in the radio which will in most cases would not activate the COS/COR line out of the radio unless both a carrier is detected and the proper CTCSS tone is detected by the radio. While software CTCSS is somewhat supported by ORP, it is still recommended to set this in the radio as it is more complicated to make sure that you are getting unfiltered audio out of the radio where the controller may not be able to hear the CTCSS to do a software decode if it has been filtered out with a high pass audio filter in the radio.

For your QTY KT-8900R radio, while I am not familiar with that specifically, you may be able to hack it. One option could be pulling voltage off of the RX led, but you need to ensure that the LED behaves as desired…meaning that it doesn’t light up when a carrier is detected but the proper CTCSS tone set in the radio is not detected. There are often mods people make to cheap radios for Allstar nodes and APRS. Maybe this one would be of use: https://4x5mg.net/2017/02/12/using-qyt-kt8900-allstar-node/

There are also other cheap radios that you can get your hands on that are better for repeater use. For example the Motorola GM-300, these are older wide band radios that can had for cheap that are much superior to the Chinese radios for repeater setups. They have programable 16 pin outputs on the back that can contain a COS line, etc. Programming them is a challenge as you need a specific dos environment to do so. You may have hams in your area that know how to do this.

Hope this helps!

Hello Tim,
I am not sure I follow what is and is not working. If you are getting ID out of the board then that means you should be getting audio from the controller into TX. Make sure you adjust the levels if needed in the ALSA mixer for your application. Also the ICS boards have multi-turn pots to adjust input and output levels. Dan @ ICS has some videos on adjusting these over on his YouTube Channel.

I recommend isolating the radio(s) and the controller. You could make a simple breakout cable into the controller. Have an LED for your PTT line, a push button pull-down circuit to simulate COS input, feed a tone generator (could be computer/phone based) into the RX side, and hook the TX audio into powered computer speakers.

It is unclear from your original post if you are using 1 radio or 2. If you are using a single radio and operating in simplex mode, the simplex mode behave a bit differently than the repeater/full duplex mode. If you are using two radios and are using simplex mode, make sure that you have proper RF isolation. If you get stray RF into the RX radio or even the cables or Pi…weird stuff can happen. For my test rig, I have a Motorola GR1225 repeater with a tuned duplexer, but I still tend to run it into a dummy load. That not only ensures that I am not blasting the surrounding area with unneeded RF while testing, but also eliminates any RF issues.