[aprssig] Receiver overload issues with Kenwood TH-D72

Andrew P. andrewemt at hotmail.com
Fri Feb 8 10:05:38 CST 2013


Greetings, all.

I was conducting some software tests that required passing data between two stations to ensure the data would be transmitted and received correctly. So, I had my transmitting station (Alinco DR-135T mobile and Byonics TinyTrak 4) and receiving station (Kenwood TH-D72 HT) sitting on the bench, both tuned to the same idle simplex frequency (I picked a quiet frequency not used for anything in my area), with the Kenwood HT about 1 meter from the Alinco's antenna. When I transmitted packets from the Alinco to the Kenwood, I could see the transmit indicator on both the TinyTrak and the DR-135T, but the TH-D72 would only occasionally squawk and acknowledge receipt of the packet (about 15% success rate). Transmitting in the reverse direction had an even lower success rate (zero packet detections at the receiver).

Could it be I was overloading the radios' front ends by being too close to the other radio's antenna? I made sure to use the factory "rubber duck" antenna on the Kenwood to minimize gain, and even turned the HT on its side to ruin polarization, but that didn't help.

Any suggestions (other than getting help because my arms aren't long enough to reach both rigs further apart)? I'm considering replacing the Alinco's antenna with a dummy load and depending on leakage to conduct the test, but I'm not sure if that will help.

Andrew Pavlin, KA2DDO
Sent from my Verizon Wireless BlackBerry


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