Hey Fellas,
I posted something in another thread dealing with the Radio Tone repeaters, but I just stumbled on this thread and it looks like a good place to discuss my repeater questions too. Sorry for posting similar questions in two threads--I know that's poor etiquette. I'm hoping that chiming in here will get the attention of the recent posters who seem to have Radio Tone repeaters working. (This thread has more-recent activity than the other thread.)
I tried the same exact same repeater setup that kpoe_28 has and it worked fine for nearby communications (within about 25'), but fell apart completely when I moved just a few hundred feet away.
Here is the description of my problem that I sent to the Radio Tone developer, Joe Chung:
"Here is what is happening: I have set up the repeater with two Wouxun KG-UVD2P radios, PTT Mode 2, using the Wouxun cables. Radios are connected to a mobile duplexer which is connected to a dual-band antenna on my home. Using two 5W Yaesu radios in the house and backyard, the repeater works fine, receiving traffic on the RX radio and passing it to the TX radio, which properly transmits the audio. As a matter of fact, it works great around the house. However, if I move just 50 metres from the house, the repeater controller stops passing audio to the TX radio. When I key up the repeater, it does not key up the TX radio and transmit what it is receiving. After I end transmission to the repeater, however, it then keys up the TX radio and transmits a few seconds of silence. This is the case when using a 5W radio. When I am at the same distance from the house and use a 50W mobile radio, the repeater does pick up the signal and transmit slightly better, but even then it is very noisy and drops the signal frequently. I had a friend monitor the repeater input (RX) frequency at the house with another radio, and the incoming signal is very strong and clear. Even with this clear signal the repeater controller does not properly pass the signal to the TX radio and key it up for transmission.
"Have you been able to use [this repeater setup] over normal distances? I would expect it to work with any incoming signal, no matter how strong or weak. Even if the incoming signal is not clear, it should be able to pass that signal on to the TX radio and broadcast whatever the RX radio was receiving. In my case, a handheld radio in my home connected to the dual-band antenna (the same one I had the repeater connected to) receives and transmits crystal clear transmission to/from 5W handheld radios that are as far away as 15km. But that same clear transmission is not being properly handled by the RT-FDR1 K repeater controller.
Joe's Response:
"Your problem is not coming from the controller, is the TX radio RF signal interference the RX radio. If the controller have audio input, it must can pass the audio to the TX radio. I think you need make sure the RX radio audio are normal or not when the TX radio is in TX. If have this problem you need to adjust the SWR of the antenna and the TX radio power, or your RF cable and other device."
So, I think Joe is saying that the receiver is getting slammed by the transmitter, such that the incoming signal is just plain lost while the TX is keyed. In other words, receiver desensitization, or "desense."
Anybody able to comment on, or confirm, Joe's description and my diagnosis of RX desense?
kpoe_28: I have the exact same setup that you have--right down to the mobile duplexer (hard to tell if I have the same brand, of course, but it appears to be the same basic thing...a garden-variety, Chinese mobile duplexer). I've tried several different configurations of antennas and radios (with and without the duplexer), and I still can't get it to work with "user radios" that are more than about 50' away. As soon as the repeater input transmission weakens the slightest bit, the whole repeater craters. Does your setup work with "user radios" transmitting from "regular" distances (1-2 clear miles)? If I have a desense problem it may be my duplexer and/or it's tuning. From whom did you purchase your duplexer, and/or who tuned it? Maybe I'll send mine to your tuner. (Please feel free to contact me directly at: mwieda "at" gmail "dot" com.
Anyway, curious to hear other's thoughts. Much appreciated.
Thanks!
-Mike
