Configuring QYT KT-8900D with VARA FM

After scouring the net and playing with settings on and off for months, I finally was able to successfully configure my KT-8900D using Digirig on VARA FM, Winlink.

First, preaching to the choir here, but Digirigs rock! I’ve been using them on my HF rigs for some time.

I’ll share my most important finding with this rig first, then some other helpful things.

I’ve been struggling for months to get this to work, squashing minor problems here and there, never sure if I could ever get this thing to work. Finally today, after exhausting every tutorial on audio settings, rig settings etc, I had a hunch… Read the Manual (but look for things that may be impacting my setup… no manual tells you how to config for a particular digital mode on UHF/VHF!). I had two KT-8900D radios set up at my QTH, both with digirigs, the same home brew cable, similar computers. Both would key the radio and I could hear packets on both sides (via a 3rd radio listening) but they just wouldn’t respond to each other. Then I tried this:

Disable both “Squelch Tail Elimination” and “Repeater Squelch Tail Elimination” (menu 53 & 54) on both rigs.

I gave it one more connect try and BOOM it worked!!! Supposedly this feature is common with cheap Chinese radios, and may have thwarted my attempts in the past to get these rigs running. I had focused mostly on audio issues (which are still important) but did not solve my issue.

So since there is no documentation or forum mention of this, I wanted to get it out there, that this was the key to my success in getting this little cheap rig to work. I have much to do to test this out in the field, but this was a promising sign. Would love to hear from others about this rig specifically (those that have successfully used them, not the naysayers of these spatter prone products) or other inexpensive rigs.

My goal here is to use these rigs to inexpensively set up a messaging infrastructure in our county to serve as a backup in emergency response situations. We don’t have the big bucks that others have to build motorola or icom level fail safes, so these Chinese wonders will have to do.

Other things I have found helpful:
-Use a digirig. They are rugged, effective, simple, and cost effective.
-Buy the USB cables from digirig with ferrite cores on them. They prevent RF issues, are a fair price, and high quality.
-Move your antenna away from the computer, they don’t play well, especially if you use BlueTooth accessories.
-Set squelch to zero, feed the audio to the computer so you don’t have to hear it.
-Use a 3rd radio to monitor frequency, spend 25$ on a beofeng for this
-I like the KT-8900D because it’s cheap, small, and has a 3.5mm TRRS audio jack with mic and ptt on the back
-Do all the audio stuff Digirig suggests, then use the “Auto Tune” feature to dial in your settings.
-As mentioned above, disable both Repeater & Squelch Tail Elimination (menu 53, 54)

TRRS pinout that worked for me:
Digirig → KT-8900D
T —> R2
R1 → R1
R2 → T
S —> S

Good luck! Open to feedback



Very nice report.

73 Constrainted

You did Not state, specifically, which ports to plug each cable end into. When using this harness, I have tried using the Radio’s DATA Port to the Digirig’s AUDIO Port, with no results!
Then I tried using the Radio’s REAR Speaker/Mic Port to the Digirig’s AUDIO Port. I was able to receive Audio through the Digirig, into the computer. But then, my Winlink & Vara-FM would NOT key the radio’s PTT switch, for Transmitting. Do you have any tips, ideas, or change of PORTS? Because this still isn’t working.

Thank you for this!!!

I missed this question when you posted it weeks ago. Did you solve the problem with PTT? If not, please post your Device Manager and Vara FM Settings → PTT configuration windows.

73 Constrainted

Dear Constrained, 02-29-24

Its been so long ago, I have just stopped with Winlink for the moment. My DigiRig is working fine, while using my Echolink program. It receives and transmits properly. I think the problem May possibly lie with the Winlink & VaraFM programs? Or it may have been the wiring rig, I was trying to make up for use with my QYT radios?

I have just purchased a new wiring harness, from Amazon that is a pre-built, TRRS to 4-way pig tail adapter. I will attempt another wiring harness soon!

Thanks for responding,

Chris – KE4WRN

I am having success with having it plugged into the spk/mic jack. I have my Digirig inline with a QYT 8900D & an EVOLVE III (jankapotomus) laptop running an APRS digipeater/iGate here at the QTH 24/7. I am using the APBK-Gate software which is just pretty much a simple usage of Direwolf. I also have it working on Winlink Packet & VARA FM. For the packet modem I use SoundModem for windows. I already had the software configurations working with a different radio so all I had trouble with was figuring out the pin out to build a cable turning off Squelch tail eliminators in the radio helped too.

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Did you use the Pin out shown in the first comment? (See Below)
“Digirig → KT-8900D
T —> R2
R1 → R1
R2 → T
S —> S”
Thanks, Chris - KE4WRN

I used the pinout listed in the owners manual. There is another topic on this site discussing this. I commented on there in more detail about the pinout used. There was an original post on that thread that I followed which matched what the owners manual stated. There was another fellow that had to switch the audio wires, but mine matched the original post I believe which also follows what QYT listed in the manual. However, there may not be much quality control on this radio for that particular 3.5mm jack since it will function even if they switch the wiring. Just up to the user to have to figure out if utilizing the port.

- J.D. Fisher
73 de KI5MLR