using a JR radio as a slave buddy box on 9x?

[ProLine]

I have a er9x/frsky moded TR9x tx that I'm trying to make my JR or dx7 be a buddy box to. The jr puts out a 1.5vpp ppm data stream but the 9x will not respond. I've setup a mix in the 9x and think that's all working. Not having another 9x to try I don't know if it's a level issue, 9x failure, or my programming? I've added the 1k resistor mod to the 9x. Not knowing what the jr should output is also confusing. I've tried several jr radios as well as my dx7, they all output 1.5vpp when loaded and connected to the 9x trainer port.
I see a lot of posts about using (2) 9x's that work, and using a 9x as the slave to another brand radio, but no mention of the 9x as the master and another brand name as the slave that I can find?
Could someone please sort this out and let me know it works, and if it does, what I'm missing here. The 9x outputs 5vpp and maybe I have to amplify/convert the jr to 5vpp to make it work?
Something I will try if all else fails.
Thank you to the one(s) that have the answer that works!
Proline

[disco stu]

Does the 9x work as the buddy itself fine? I've only used the 9x as buddy to JR master, and that was fine once I remembered about pulling out the module. Just wondering if you've made sure the cable etc is all fine

I will have a go with mine when I get a chance