Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]
<prev [Date] next>
[Advanced]
 <prev [Thread] next>

R: LF: TXing WSPR/MF on an indoor loop

from [[email protected]] [Permanent Link][Original]
To: <[email protected]>
Subject: R: LF: TXing WSPR/MF on an indoor loop
From: "[email protected]" <[email protected]>
Date: Sat, 26 Jan 2019 08:49:28 +0100 (CET)
Reply-to: [email protected]
Sender: [email protected]
Hi Stefan,

I just checked on WSPRnet and red you got plenty of reports from your QRP activity so my 3 spots are a drop in the sea.. but

3 spots:

TimestampCallMHzSNRDriftGridPwrReporterRGridkmaz
 2019-01-26 03:34  DK7FC  0.475683  -27  0  JN49ik  0.01  IK1HSS  JN35tb  493  190 
 2019-01-26 03:28  DK7FC  0.475683  -25  0  JN49ik  0.01  IK1HSS  JN35tb  493  190 
 2019-01-25 16:10  DK7FC  0.475683  -27  0  JN49ik  0.01  IK1HSS  JN35tb  493  190 
the rx is a direct conversion rx with a simple bandpass input filter.. it is sensitive but lacks of course of image rejection and other features that make a real receiver another thing :-)
The strange point is how the 3 spots are spreaded in the period: 16:10 03:28 03:34..

Some years ago I made some trials on 137 kHz using an (outside) 2 turns loop (5x5m) and it was funny

73, Marco IK1HSS


----Messaggio originale----
Da: [email protected]
Data: 25-gen-2019 15.23
A: <[email protected]>
Ogg: LF: TXing WSPR/MF on an indoor loop

Hi MF,

A few days ago i took some RF litz wire and built a loop that is now
hanging on the wall inside my home, just 1m besides the bed :-) (no XYL
here spoiling the fun). The loop is beaming to about 150/330 deg.

After playing some days on 160m (an unusual high frequency, witch feels
very strange. And the band is full of unknown callsigns!!) i did now
move down to more or less low frequencies, the 630m band!

About 10 nF is needed to series resonate the loop. It has about 2m x 2m
of size. The antenna current is not stable because the WIMA FKP-1
capacitor becomes warm during the 2 minute WSPR sequence. But the
maximum current in the loop is 14 A. That explains why the cap becomes
warm. A small parallel variable capacitor tunes to resonance. It is
tuned so that the upheating capacitor runs into the resonance point in
the middle of the WSPR sequence, then it runs out of the resonance by
upheating further. It can cool down during the following quiet periods..

14A into a 4 square meter loop at 475.7 kHz, how much ERP is that? The
PA consumes about 3.5 A at 13.8V, i.e. about 50 W.

The system will run over the weekend, even during daylight. The signal
generator is a Raspi which will have no internet connectivity from now
on, so let's hope the time offset stays inside the accepted range for
this experiment.

What will the best distance be? So far the band is closed but i'm
optimistic to crack the 1000 km distance with this QRP setup.

73, Stefan



[More with this subject...]
<Prev in Thread] Current Thread [Next in Thread>
Previous by Date:  Re: LF: Re: TXing WSPR/MF on an indoor loop, Markus Vester
Next by Date:  Re: R: LF: TXing WSPR/MF on an indoor loop, DK7FC
Previous by Thread:  Re: LF: Re: TXing WSPR/MF on an indoor loop, Markus Vester
Next by Thread:  Re: R: LF: TXing WSPR/MF on an indoor loop, DK7FC
Indexes:  [Date] [Thread] [Top] [All Lists]