Re: LF: EbNaut tests 137.542 kHz

[Markus Vester <markusvester@aol.com>]

Hi Alex,

your transmitter and PA are fine, only the oscillator would need a bit more stability. A few minutes after the beginning of each transmission, the frequency starts to drift down by about a few milliHz:

16:30   137542.0105 -> 137542.0081  -2.4 mHz
17:00   137542.0117 -> 137542.0083  -3.4 mHz
17:30   137542.0112 -> 137542.0080  -3.2 mHz

I assume that this is a temperature effect, and the heat generated by the PA or power supply takes some time to reach the oscillator's clock crystal. You could try to better thermally separate, insulate or stabilize the oscillator. However a Rubidium or GPS-locked reference would be a perfect solution.

Best 73,
Markus (DF6NM)



-----Ursprüngliche Mitteilung-----
Von: Alex R7NT <r7nt.73@gmail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 31. Jan 2017 9:13
Betreff: Re: LF: EbNaut tests 137.542 kHz

Marcus, TNX for the info!

Unfortunately, I don't have enough level of technical knowledge for correct EbNaut.

I think the problem in my specific PA - D audio PA on LF

I need time to find a solution. I stop all tests with EbNaut until resolving time

73! Alex R7NT  136.73.ru

2017-01-30 16:15 GMT+04:00 Markus Vester <markusvester@aol.com>:

Hi Alex,

your signal was very strong in the evening and well visible in the spectrograms. Unfortunately the curved phase plot shows that the transmitter drift is still too large, so EbNaut cannot reach it's full sensitivity.

Best 73,
Markus



-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 29. Jan 2017 17:58
Betreff: Re: LF: EbNaut tests 137.542 kHz

Hello Alex,

Decoded the 16 UTC message. I tried a few of the earlier messages without success, the path was not open yet it seems...
Frequeny offset abt 10 mHz, no decode when not correcorrected.

73, GL, Stefan

Am 29.01.2017 13:29, schrieb Alex R7NT:

Freq:  137542.00 Hz

Code:  8K19A

Symbol:  2.0 s

Len:  8
Time:  1312.0 s (21m 52.0s)

Start times: every h:00 and h:30  until abt 17:00 UTC

73! Alex R7NT  136.73.ru

01291741_sym_delayed_drift.png
Description: PNG image