[aprssig] Receiver overload issues with Kenwood TH-D72

Ray Wells vk2tv at exemail.com.au
Fri Feb 8 16:38:20 EST 2013

On 09/02/13 03:05, Andrew P. wrote:
> 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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I think that if you use a dummy load on both radios your problem will 
vanish. By using antennas on the radios you would have had RF getting 
into everything.

Ray vk2tv

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