Re: LF: DK7FC on 137715

[HB9ASB <hb9asb@gmail.com>]

They always come back, dear Stefan!
Your signal was quite strong here, perfectly audible. And this with only 40W!
I was using my Inverted L, 12m high and 40m long. The same antenna I'm using for 160&80. TX power was 1kW, antenna current not measured. Thank you for the nice QSO

73 de Toni, HB9ASB

2011/3/12 Stefan Schäfer <schaefer@iup.uni-heidelberg.de>

Thank you Nicolas, Tony and Markus!

Yes, today i have resonated my new "office antenna" with a suitable coil.

Some data about the system:

Wire about 90 long and 25m (average) up. The overall losses seem to be 10 Ohm although the coil is just out of 0.75 sq mm loudspeaker cable. The system is exactly resonated and matched to 50 Ohm. So i get 2 A antenna current at about 40 W :-)
Markus dis some field strength measurements and we estimated an antenna efficiency of about 1%.

The todays tests and QSOs were done with 40 W TX power out of a 12V class E PA.

It is all a very loose construction in the shack, just for testing. I will make a better coil. Currently i am using my DDS VFO at 137.715 kHz with a DFCW shift of 1 Hz.

I can remote control the whole TX! So i do not have to stay all the time in the institute but can do QSOs from anywhere where i find a internet connection :-) I just can't change the frequency but i am working on a TX converter and then use SpecLab for TXing. Currently i am using Rik's QRS programm which works excellent!

The resonated antenna is lifting the grabber RX signal by 20 dB without affecting the SNR as it seems. I will check if the TX antenna is rather suitable as a RX antenna as well.

Currently i can see S57A answering on my call. I can see it on OE3GHBs grabber but not on mine :-( Hopefully conds will become better in the late evening...

Tnx to DF6NM for the first and HB9ASB for the second QSO on this antenna! HB9ASB is my first contact on 137 kHz in HB9, mni tnx!! :-)

73, Stefan/DK7FC

PS: Now you are all on VLF and i am coming back to LF. Isn't it funny? :-)



Am 12.03.2011 20:45, schrieb F4DTL@aol.com:

Nice signal here Stefan...

 

F4DTL Nicolas JN18FP
RX : Icom IC7400
Ant: Wellbrook LFL 1010

http://lfistes.erst.azerttyu.net/