AW: LF: new on 137kc

["Michael Peters" <m.peters@peters-placke.de>]

hello markus, hello alan, hello group,

 

 

thanks for info`s about the loran tx on the island of sylt...

 

i have check the distance - is 35 km to the tx...

 

it was not enough time to build a loop and so i hope my bandpass (from rx041 df8zr) can reduce the interference.

 

i will report when i be back from my holiday

 

 

73 michael dk5na

 

 

-----Ursprüngliche Nachricht-----
Von: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]Im Auftrag von MarkusVester@aol.com
Gesendet: Montag, 7. März 2005 23:32
An: rsgb_lf_group@blacksheep.org
Betreff: Re: LF: new on 137kc

Hello Michael,

the coordinates of the Sylt Loran station are 54° 48' 29.975" N, 8° 17' 36.856" E. This is on the southern part of the island, and ranges to Romoe vary from 32 to 46 km. The nominal peak power of the pulses is 250 kW on 100 kHz, so you will have to expect a fieldstrength of 150...100 mV/m. This can produce several volts on a typical amateur-sized Marconi. The problem is mostly that the Loran emissions contain significant spectral energy outside their designated passband (90 - 110 kHz).

- You can try to reduce the interference using a loop receive antenna. The disadvantage is of course that you won't be able to hear any signals from the null directions. You will also have to detune  your transmit antenna during receive to avoid degrading of the loop pattern by mutual coupling.

- To prevent the Loran signal from overloading your receiver frontend, a bandpass filter will probably be mandatory.

- As the pulses are short (< 200 µs), a noise blanker in the receiver can be quite effective. It can however remodulate the Loran repetition rates onto other signals (eg. DCF 39) and create weak spurs which could be confusing in extremely narrowband observations.

I wish you a nice holiday, and success for your first steps on this fascinating band.

73 de Markus, DF6NM