Re: LF: 8 dB sensitivity improvement on DK7FC's LF RX/grabber. Activity please

[Warren Ziegler <wd2xgj@gmail.com>]

Stefan,

 

    Excellent work !

Is the T/A window around 137.78 clear?

I can transmit QRSS tonite if you are interested.

 

 

73 Warren

 

On Thu, Jan 1, 2015 at 11:04 AM, DK7FC <73dk7fc@googlemail.com> wrote:

Hi LF,

Happy new year to all over the world!

In the afternoon i have done some maintenance on the LF/MF grabber PC. Deleted about 1 million jpg files (> 100 GB) and adjusted the brightness settings for the grabber displays. It is active again now with mch improved sensitivity. In the afternoon the wideband grabber window show clearly that most of the residual man made noise is now coming from DCF39 and HGA22. 136.5 kHz is clearly the best frequency for CW.

>From the 2 seconds long daily breaks while DLF on 153 kHz switched from 500 kW to 250 kW at 19:59:58 local time i know that there will be a fignificant reduction of my background noise level on LF/137 kHz.

Now it turns out that there is an improvement of 8 dB on LF!!!
On MF there is nearly no change, just a small QRM trace disappeared. Average background noise is the same. LF and MF is using the same active antenna frontend!
On VLF (separate antenna) there is no significant change.

Here is a complation of images showing the differences before and after the closure of DLF/153kHz: https://www.dropbox.com/sh/y6vccbmn9z9v97g/AACTB7MCUVxOfYK0PXtVX1A5a?dl=0#lh:null-01_3_31.DEC_23.30UTC.jpg
Unfortunately i forgot to stop my MF WSPR transmission over the night so there may show some QRM on each 10th minute.

Now, this night i will watch/receive on LF and am asking for LF stations to transmit, especially the far Russian and TA stations. Let's make it an active night while am silent (exceptionally :-) ). In the evening i am trying to make some QSOs...

Let us make a sked for a LF CW test on the weekend, maybe on 10 UTC on 136.5 kHz. Anyone interested, e.g. DK1IS?

73, Stefan/DK7FC

--

73 Warren K2ORS
                WD2XGJ
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