Return to KLUBNL.PL main page

[Top] [All Lists]

Fw: LF: 476.181 kHz from indoor loop

To: <[email protected]>
Subject: Fw: LF: 476.181 kHz from indoor loop
From: "Markus Vester" <[email protected]>
Date: Thu, 25 Jun 2015 01:15:00 +0200
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20150623; t=1435187703; bh=Do88RqjSx5suiEkqatbhYJm7sGmgS4wBVJ6MZhEGK9U=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=eV7kPk6y+tbcs2yzzq4zAoxX5vxlRJw5Y/of+c3jpIBTEBiI7juMWrawZSyPUD9mg ITRFPxrffGcyxDqcBCkeKBOI0yf6HB8NrMpVSSLHx4dOst+EUYV2gCwmK2RPenHGJy eTUVEydryJ9OGaNjrqTqyizIENlHW3w5Bc6zN5Io=
Importance: Normal
Reply-to: [email protected]
Sender: [email protected]
Hi Domenico,
no, not me. The strong signal in is probably IQ2MI from Milano sending QRSS-3.
To help save the planet, I have now reverted to the omnidirectional electrical antenna and a 1.5 W QRP transmitter (ie. the driver of my class-D LF PA). The antenna is currently in the low position 3 m above the roof so radiated power is only around 5 mW. Now sending occasional WSPR-2 sequences on 475.790 kHz.
All the best,

Sent: Wednesday, June 24, 2015 11:02 PM
Subject: LF: 476.181 kHz from indoor loop

Good evening Markus,
please take a look to my Argo screenshots (every 5 minutes)

i'm not shure if this is your signal becouse my rx is not calibrated. Are you sending some psk?

73 and have fun with your loop!

Domenico iz7slz

On Wednesday, 24 June 2015, Markus Vester <[email protected]> wrote:
Hi Mauro,
this is a single turn loop, around 3.5 m wide and 3 m high, now consisting of the braid of a piece of RG-216 coax cable. Required capacitance for 475 kHz is 7.1 nF, made from five 33nF FKP capacitors from the junk box, plus a couple of styroflex for fine tuning. It's fed through a small ferrite toroid, 32 turns primary, 4 secondary. Loop resistance at MF is about 0.57 ohm (Q~83), presumably largely affected by losses from the nearfield environment (reinforced walls, house wiring, etc). Using 35 W RF the loop current is 7.8 A. Some pics of the former LF loop tests (32 A, 250 uW) are at .
The purpose of this experiment is mainly to be able to provide a signal for receiver testing, which (unlike my Marconi) can be left on air during unfavourable weather. But it's really inefficient: An old ENI broadband linear amplifier converts 140 W DC into 35 W of RF, of which only ~ 2 mW are radiated.
Yes it works also for WSPR - a couple of nights ago I did get spotted by DK7FC, F59706 and SP5XSB. During the daytime the range would be much shorter, and the signal is definitely too weak for a decode in Heidelberg.
Best 73,
Markus (DF6NM)

Sent: Wednesday, June 24, 2015 7:30 PM
Subject: Re: LF: 476.181 kHz from indoor loop

very interesting for WSPR tests !

few questions:

- mono-turn or multi-turn ??
- what are you using for match to TX ???

many thanks and
73 de Mauro IK1WVQ

At 12:11 24/06/2015, Markus Vester wrote:
>I am currently running a DFCW-60 beacon on 476.181 kHz, using the
>same 10m^2 indoor transmit loop as previously on LF. With 35 Watts
>of RF input, estimated radiated power is around 2 mW, with lobes
>pointing west and east.
>The daytime groundwave signal is visible in the bottom panel of the
>DK7FC MF grabber. Going by the CCIR plots for 3 mS/m conductivity,
>the groundwave attenuation for this distance would be about 23 dB in
>excess off lossless 1/r propagation, resulting in approximately 0.2
>uV/m in Heidelberg.
>Best 73,
>Markus (DF6NM)

<Prev in Thread] Current Thread [Next in Thread>