[hpsdr] Atlas based HPSDR PureSignal

[Kjell Karlsen]

Hi Bruce.

I have used the directional coupler on Alex for feedback of the signal to  
Hermes. But of course I do not use the DC! I just take the FWD RF signal  
 from the junction between R2 and D1, then via an attenuator to X1, the  
internal connection to the Alex HPF. This connection and attenuator is  
easily installed on the PCB using a short length of mini coax and some  
0803 SMD components. Abhi has described this for ANAN-100/ 100D. I think  
it is on the Apache Labs site somewhere.

If you use an external PA, then you need an external Directional Coupler  
too.

73, Kjell




På Wed, 29 Jan 2014 12:30:36 +0100, skrev Bruce Beford  
<bruce.beford at myfairpoint.net>:

> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi George.
> No, we cannot use the DC voltage from the SWR bridge on Alex. We need to
> feed back a sample of the actual RF waveform to the receiver ADC on  
> Mercury
> for pre-distortion compensation to work. This will require a separate
> coupler or "sniffer".
> Regards,
> Bruce N1RX
>
>> Hi Phil,
>> actually, in Atlas based systems there is an Alex transmit board with a
>> RF power directional coupler installed. These dc voltages from the
>> coupler provided at the 4-pin connector, could they be used for
>> predistortion? Or do we need an additional coupler when all the
>> modifications you described are done?
>> 72, Georg, dl2kp
>
>
>
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