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Re: LF: RE: Diplexer 137 / 74 kHz

To: <[email protected]>
Subject: Re: LF: RE: Diplexer 137 / 74 kHz
From: "Markus Vester" <[email protected]>
Date: Fri, 25 Oct 2013 10:22:16 +0200
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Hi Victor,
 
+232 dB sounds impressive doesn't it ;-)
 
In reality the level difference is not so large. DCF77 comes in around 8 mV/m at 160 km distance, inducing an unloaded voltage of 8 mV on my antenna. Transforming from 17 ohms and loading would make that 7 mV at 50 ohms (-30 dBm, S9+43). The best signals from CFH were around 40 dB less than DCF77.
 
My LF transmitter was delivering about 55 dBm ("S9+128 dB"), and the level difference to CFH is "only" around 125 dB.
 
Best 73,
Markus (DF6NM)
 

Sent: Friday, October 25, 2013 6:09 AM
Subject: LF: RE: Diplexer 137 / 74 kHz

Very nice job Marcus,21 KV is S9+232dB!
 
73
Victor
-----Oorspronkelijk bericht-----
Van: [email protected] [mailto:[email protected]]Namens Markus Vester
Verzonden: vrijdag 25 oktober 2013 2:47
Aan: [email protected]
Onderwerp: LF: Diplexer 137 / 74 kHz

This thing amazes me:
 
As noted a while ago, I have connected a makeshift diplexer with the LF transmitter and receiver on one port, and an additional 74.55 kHz receiver to the other.  
 
At the time of writing, I am transmitting on 137.62 kHz, about 300 W making 4.2 A and 21 kV at the antenna. Now on the other RX, I can still see DCF77 on 77.5 kHz, and even some of CFH 73.6 kHz from Canada, on the same antenna which is actually radiating! There is some RX overload reducing sensitivity by some 20 dB, but the both signals are still there, and not swamped by noise from the TX or partial discharges.
 
There's a circuit and some pics in df6nm.bplaced.net/LF/74kHz/Diplexer/
 
Best 73,
Markus (DF6NM)
 
PS1 Got a good "X" from Bob around 23 UT. Should better shut up and watch! http://dl.dropboxusercontent.com/u/26404526/df6nm_74kHz.jpg
PS2 Just received a mail from Jay saying that he picked me up in WSPR-15. Should better go about transmitting again ;-) 
 
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