[time-nuts] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Poul-Henning Kamp
phk at phk.freebsd.dk
Thu Jul 16 12:23:08 EDT 2015
--------
In message <CANX10hBuaHDwaChb+wHLKen4wcwn5_R2UEn9aJZmnvL8AxZe4Q at mail.gmail.com>
, "Dr. David Kirkby (Kirkby Microwave Ltd)" writes:
>but roughly how many turns were there on the coil?
Probably too many, all things considered, but I have *no* idea.
>Do you have a circuit for the amplifier?
It was based on/inspired by a schematic I found on vlf.it
>I must admit to knowing next to nothing about antennas at the Loran 100 kHz
>(+/- a lot) frequency. How does one go about testing the antennas?
Plug it into a spectrum analyzer or oscilloscope.
Use average mode.
Trigger with a pulse generator with a period of:
6731 * 2 * 10µs) = 0.13462 Hz
and you should see the pulses.
If you have a good spectrum analyzer, you can probably do this with
a few meters of wire as antenna.
The result should look something like:
http://phk.freebsd.dk/misc/dscf0275.jpg
>That's the only thing I have got that measures impedance as low as 100 kHz.
100 kHz is practically audio, impedances hardly matter: The reflections
have wavelengths measured in km.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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