RE: LF: Belgium on 472 kHz

[Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>]

Hi Stefan,

 

no special RX antenna here. I do use my "lazy-L antenna" (11m high and 23m long) for TX and RX.

But I do use 20 to 40 dB attenuation between antenna and RX to avoid RX overload. The RX is a Kenwood TS440, a rather good RX in regard with IMD. But the attenuator still makes a difference. I think that - on LF en MF - is it good practice to attenuate the antenna signal up to the level where the antenna noise level is about 10dB (or even less) above the RX internal noise level. That way IMD is minimized while one is still sure that no signals are lost.

But it will only work if you are not a S-meter fetishist ;-)

 

Besides that I live in a rural area, apart from my own house all other "noise sources" are at least 70m from the antenna.

 

73, Rik  ON7YD - OR7T

 

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Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan Schäfer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: zaterdag 17 augustus 2013 13:30
To: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Belgium on 472 kHz

Hello Rik, MF,

I can see you can receive me at -11 dB SNR in WSPR-2 on 630m at daytime. So i assume i am weak audible? Distance is 332 km which should be the limit of the groundwave.
Your RX system must be very good. The SNR is 10...12 dB better than at PI4THT although the distance is nearly the same, and both completely over land. JO20IX looks like countryside compared to JO32KF. That seems to make a significant difference regarding man made noise. I have the same problems here :-(
Or do you have a super special RX antenna? BTW last night EI0CF reported that he's using a beverage RX ant. Nice stuff!

I'm still hoping to find the limiting factor for my RX system. Is it the non-optimal equipment or simly the location, i.e. can i improve it at this location or did i already reach the best sensitivity i can get from here. On MF i think i can't get much better, except by using directional antennas, maybe.

73, Stefan/DK7FC


Am 14.08.2013 23:42, schrieb Rik Strobbe:

Hello Stefan,

 

I hope just some days. Meanwhile I can transmit WSPR, WSJT-X etc...

A short WSPR test got me a decode from G3XKR at 630 km. Last winter I got reports from up to 2000 km (on 501 kHz) with the same rig.

 

73, Rik  ON7YD - OR7T

 

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Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan Schäfer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: woensdag 14 augustus 2013 19:31
To: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Belgium on 472 kHz

Hi Rik,

Good news! I hope to meet you on the band soon when the PA is working again. How long will it take to repair it?
Will you try WSPR during that time, using QRP?

Vy 73, Stefan/DK7FC


Am 14.08.2013 18:23, schrieb Rik Strobbe:

Dear all,

 

from today on Belgian holders of a HAREC licence are allowed to use 472-479 kHz with 5 W EIRP on secondary base. No mode limitations.

So far the good news.

Bad news is that I started up the TX (after some months of rest) and after one minute the was a "bang". A short check showed that the PS failed (went from 15V to 22V). The PS was fixed (15V stabilisator replaced), but the 22V also destroyed some IC's that are not on the sheft in my shack. I have to order them and it can take some tome to get QRV with full power (250W).

Fortunately I stille have the 6W transverter working, so I can be QRV with low power (estimated ERP = 20 mW) from now on.

 

73, Rik  ON7YD - OR7T