I answered below:

[]s

>Rafael Vidal Aroca wrote:
>
>
>>    Hi guys, i'm working in a tracker project and strange things are
>>happening. I tested it on a pair of Motorola's Talkabout and i get
>>100% of reception. All the packages i send i can receive.
>>
>>
>
>Ok, it works with low power.
>
>
>
>>   But when i try it on a pair of Motorola's PRO5100 that are bigger
>>radios, most of the signal did not arrive. I lost about 50% of the
>>transmited packets.
>>
>>
>
>Several things come to mind.  One is the audio filtering on the second
>radio.
>
    I tried to disable the 3 configurable filters that the radio has and
nothing. Audio processing filter, "filtered audio" output and flat audio
output too....both with no success.

>  Perhaps the bandwidth is too narrow for the baud rate you are
>attempting to send.
>

    Well, i'm using AX.25 packets at 1200bps, and if the bandwidth is
too low, why sometimes several packets can be sent and sometimes none
get sent?

>Maybe the levels of the signals need to be
>adjusted?  I highly suspect that RF is entering your transmitter thru
>your MIC/hookup cable or even the power leads and garbling the data
>during transmission.  Check the SWR, relocate the transmitting antenna,
>shield the audio connection cable better.  I would start by viewing the
>received data on a scope to see if it's distorted or too low/high in
>amplitude.
>
>

    Well, this seems to be the solution, but everything i try makes no
change in the circuit. Yes, i'm not using cables with shield, but the
motorola's connector to the radio is much like an ide connector of only
20 pins....the audio, ptt, channel control...all enter there...

    Thanks for the pacience

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