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Re: LF: CW on 477.5 kHz and first MF impressions and my new MF RX...

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Subject: Re: LF: CW on 477.5 kHz and first MF impressions and my new MF RX...
From: Stefan Schäfer <[email protected]>
Date: Sun, 17 Jun 2012 01:04:00 +0200
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MF,

Some notes on my first day on that band.

My impression from the first day on that band is that the QSB is much much higher than on LF! BTW DJ2LF became much stronger after some time, also audible.

After working PA3ABK and getting a real impression what that band is promising regarding QSOs, i've just worked G3KEV who was very strong here, starting 439 and later 579 or more. I have no S meter, so its just a guess. But the normal S meters also show a guess :-)
The HF reports, RST 599...  In not even 1 of 1000 HF CW QSOs i got a T report that differs from 9. And S... With or without a preamp or attenuator? The only real information is R! Unfortunately most amateurs give R=5 even if you have to repeat the call several times...

My little homemade MF receive is not even 1 day old and now i've got the proof that it seems to be very sensitive! Arround 500 kHz the signals are 30 dB down compared to 472...479 kHz, due to the internal filters. Anyway there was very good copy of the stations in that range. Looks like the high selective filters are not necessary there on MF. No problems like on LF with DCF and HGA and DLF... Soon i will publish the schematic for this RX, after some further minor changes.

So far the receiver is a DC receiver using the SBL-3 as the mixer. The LO is xtal 1.8432 MHz/4 (done by a CD4013), i.e. 460,8 kHz. Actually it is 461 kHz since my xtal is very old it seems. So the band is converted to arround 11...18 kHz and can completely be shown in a spectrogram on a PC. But what i want is a receiver that needs no PC in addition, so i need another mixer and a VFO that converts the signals in the base band, i.e. to 750 Hz or so. Also i would like to have a AGC and a noiseblanker. I've already some ideas how to realise that...

Very nice and promising band!!

73, Stefan/DK7FC

Am 17.06.2012 00:23, schrieb Tracey Gardner:
 
I had a poor copy on DJ2LF here due to the QRN, had that not been around he would have been quite readable.
 
73s Tracey G5VU
----- Original Message -----
Sent: Saturday, June 16, 2012 11:05 PM
Subject: Re: LF: CW on 477.5 kHz

Thank you Jan for the QSO, Chris and all the others for the many reports my email.

Yes, it was a historic moment for me! The first amateur radio station i ever heared on MF (except 160m of course). The QSO was like on HF, without any problems! I can well imagine that this is a CW band where real time QSOs can take place. And this night is in summer and with high QRN, so winther must be wonderful.
No contest stress like on HF and still a special place below 1 MHz :-) 137 kHz is the real challenge of course but its very nice to have a real QSO band now!

I will go on to improve some things here and will see how the active ferrite antenna performs on MF, maybe cancelling out the QRN...

The QSB was interesting and it clearly shows up that the ground range distance is much lower. I got audible copy from the UK but nothing at DJ2LF in 175km distance...
Will continue to listen and prepare my remote link to key the PA here while sitting in the forest and receiving there :-)

73, Stefan/DK7FC


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