[hpsdr] Comments on setting up PureSignal

[Helmut Oeller]

Hi Brian,

 

The ADC clipping level is typically + 5 dBm and in the given configuration
with a 20 dB fixed gain preamp the limit for the total array is -15 dBm.
With the 31dB maximum step attenuation in front the RX input limit is 16
dBm, far below the device ratings of the DAT-31. 

Assuming an external 1kW-amp (+60 dBm) and a 30 dB coupling loss of the RF
sampler you need an additional pad with at least 14 dB attenuation. If you
run the system under that these extreme conditions (without the possibility
to adjust slight deviations in the frequency response of the  RF coupler) it
should be verified that NO additional distortion is generated in the DAT or
preamp in the entire frequency range.

All testers, who used a RF tight Hermes RX port, had not issues with the PS
performance. No further comments regarding stray coupling, hi.

 

73, Helmut, DC6NY

 

 

Von: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Brian Lloyd
Gesendet: Mittwoch, 26. Februar 2014 18:07
An: Bill Diaz
Cc: hpsdr at lists.openhpsdr.org
Betreff: Re: [hpsdr] Comments on setting up PureSignal

 

On Wed, Feb 26, 2014 at 10:49 AM, Bill Diaz <william.diaz at comcast.net>
wrote:

***** High Performance Software Defined Radio Discussion List *****

 

Brian,
    Based on extensive testing by Mukesh, KE3VG, with a ClearRF sampler,
good results were achieved on 20 and 40 meters when the external sample
level was 6db higher than the observed internal crosstalk level on that
band.  This may not be practical on the higher bands due to the higher
crosstalk at higher frequencies.

 

Well, I stand by what I wrote. Every radio/amp/coupler/frequency combination
will be different. Each person is going to have to adjust their setup to
match their equipment. I wanted to lay out the PROCESS by which maximum
performance can be achieved. I didn't address the issues of filter selection
or other parameters. Someone who knows those effects better than I should do
that. Regardless, what I posted is correct and useful.

 

As a final point, no one seems to be addressing the issue of reducing stray
coupling inside the ANAN 100. That alone would provide the biggest
improvement and make all the other settings less critical.

 

-- 

Brian Lloyd, WB6RQN/J79BPL      Das Bild wurde vom Absender entfernt.
706 Flightline Drive
Spring Branch, TX 78070
brian at lloyd.com
+1.916.877.5067

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