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Re: LF: TXing WSPR on 630m on a Raspberry Pi, Stefan in QRPPPP...

To: [email protected]
Subject: Re: LF: TXing WSPR on 630m on a Raspberry Pi, Stefan in QRPPPP...
From: DK7FC <[email protected]>
Date: Mon, 23 Mar 2015 21:12:14 +0100
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Hi Mauro,

Yes, for a TX power below 20 dBm i do not care to much about spectrum so i just spent a simple pi filter. For higher power levels i would use a higher order filter, like my PA does anyway. I can see the in-band-spectrum on my local receiver at (RX still on the table here for testing) with > 50 dB SNR. Here, the spectrum looks very clean.
73, Stefan

Am 23.03.2015 19:20, schrieb IK1WVQ Mauro:
Hi Stefan,
I use the RASPY from 2 years to produce WSPR and QRSS (I wrote a software to do this).
Consider what the RF is produced by the internal fractional-divider
"modulated" by a DMA sequence, to increase the resolution of the
The result is a NOT SO CLEAN spectrum !!! take a lock with a spectrum
analyzer !!
When used with lo power this is not a problem (my "PA" in HF is a
74AC541 all paralleled.. 450mW @ 30meters)
My QRSS software can use only the fractional divider, without DMA ..
The spectrum is VERY clean, but it is impossible to generate the WSPR tone .. only QRSS, CW and OPERA ...
73 de Mauro IK1WVQ

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