|Subject:||Re: LF: 137.7770 kHz|
|From:||Michel Brunel <[email protected]>|
|Date:||Mon, 3 Jun 2013 10:11:47 +0200|
|References:||<[email protected]> <[email protected]> <[email protected]> <[email protected]>|
After refurbishing the 137 kHz preamp, I'm back on LF - Rx only -
The wideband 455 kHz ceramic filter has been replaced by a 600 Hz
mechanical filter, mainly to improve the RX's dynamic.
I don't know if it is any better yet ...
The frequency chirp is noticeable on the night capture. Hope you
can get rid of it soon.
The Loran-C lines are best received during the day due to a lower
band noise. They give a precise idea of the overall stability.
73 and HTH
Michel - f5wk
Le dimanche 2 juin 2013 à 16:07:53, Jcraig écrivait :
> Hi Stefan, Markus and Group,
> Thanks for looking Stefan. The ERP was down until the second Decca
> module was switched in at 2330 bringing the output power from 150 to
> 450 watts (3.2 amps to the aerial.) After this the signs appeared on
> the DF6NM grabber.
> Thanks to Markus for the detailed report. The next steps are to reduce
> the 0.02 Hz chirp, frequency offset and phase glitches. I am grateful
> for your finding these and providing a progress report.
> The breadboard comprises an Oscilloquartz 8663 10 MHz DOCXO which feeds an
> AD9851 clocked at 60 MHz. The dds programming and keying is done with
> an arduino. The DOXCO is calibrated against WWV by averaging out the
> diurnal ionospheric doppler shifts over a period of a week.
> I think the offset could be improved by setting the DDS to 13.777 MHz
> and dividing by 100 and the phase glitches/chirps could be reduced by
> using a better power supply for the DOCOXO. Bumps can be seen in the
> spectrum of the DOCXO at 10 MHz which are presumably due to the
> heaters being switched on and off and causing supply voltage
> Thanks also to Vern who is still running his grabber with strong signals
> being copied during the day. I'll leave the TX on until tomorrow ~1000
> 73 and tnx agn
> Joe VO1NA
> This electronic communication is governed by the terms and conditions at
|<Prev in Thread]||Current Thread||[Next in Thread>|