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| To: | [email protected] |
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| Subject: | Re: LF: 137.7770 kHz |
| From: | Michel Brunel <[email protected]> |
| Date: | Mon, 3 Jun 2013 10:11:47 +0200 |
| In-reply-to: | <[email protected]> |
| References: | <[email protected]> <[email protected]> <9F4D930ED1F64F7C974C9F3570FE5DEA@White> <[email protected]> |
| Reply-to: | [email protected] |
| Sender: | [email protected] |
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Hi Joe, After refurbishing the 137 kHz preamp, I'm back on LF - Rx only - The wideband 455 kHz ceramic filter has been replaced by a 600 Hz mechanical filter, mainly to improve the RX's dynamic.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 > fluctuations. > 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 > utc. > 73 and tnx agn > Joe VO1NA > This electronic communication is governed by the terms and conditions at > http://www.mun.ca/cc/policies/electronic_communications_disclaimer_2012.php --
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