Hi You can spend *way* to much time analyzing these gizmos. The simple approach is (almost) always better:
1) How much room do I have? 2) How high can I get it? 3) What sort of coil form is available cheap? 4) How much inductance is in a few turns? 5) What frequency(s) am I interested in? Simple math will tell you if the inductive reactance is > 50 ohms. If so, you need a transform(er) of some sort. A high-z amp is one way to transform the impedance. Wind it up and give it a try… Bob On Jul 8, 2014, at 6:17 PM, Poul-Henning Kamp <[email protected]> wrote: > In message <[email protected]>, Magnus Danielson writes: >> Hej Poul-Henning, >> >> On 07/08/2014 09:59 PM, Poul-Henning Kamp wrote: >>> In message <[email protected]>, Magnus Danielson writes: >>> >>>> I have a FS700 sitting here, but no antenna. There should be other >>>> signals than LORAN-C/CHAYKA available, such as DCF77, MSF60 and the 162 >>>> kHz signal from outside Paris. It would be pretty straight-forward to >>>> put up a frame and make a number of turns of wire, and put a low-noise >>>> amplifier up in the attic. What existing projects should I look at or >>>> take inspiration from? >>> >>> http://phk.freebsd.dk/loran-c/Antenna/ >> >> What is your loading on the coil? How many turns? Schematic? > > No loading, I wanted flat frequency response. > > No ideas how many turns, it's not critical. > >> Cooking up a low-noise amplifier for these frequencies seems relatively >> simple, but it is always nice to see what others have done. > > I just winged it, I looked at the stuff at VLF.IT then the AD797 > data sheet and when it worked well enough I stopped. > > I have also built a "monopole" antenna, based on the schematic on page 6 > in this article by Chris Trask: > > > http://home.earthlink.net/~christrask/Complementary%20Push-Pull%20Amplifiers.pdf > > The performance is astonishing: it pulls in everything from the > Schumann resonances and ~10kHz russian "Omega-like" naviagation to > 100 MHz FM radio, but also every source of noise you can imagine > in your neighborhood. > > In difference from the loop which needs none, this antenna needs a > really good earthing. > > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > [email protected] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
