[time-nuts] Active LORAN antenna

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Aug 26 21:16:06 UTC 2011

In message <4E580972.6080103 at pacific.net>, Brooke Clarke writes:

>It looks like the noise floor is maybe 10 dB higher than the AMRAD
>or 30 dB higher than the McKay Dymec active antenna.

If you are basing that claim on the SA plot in my blog-post, you
instantly win the "inappropriate apple-oranges comparison price of
the year"

First there is nothing even remotely close to a natural noise-floor
in the LW broadcast band in the middle of a city here in Denmark,
there is far too much EMI from switchmodes etc etc.

Second, there is a significant impedance mismatch between the antenna
and my SA in that plot.   I backhaul the signal over a balanced
twinax cable (78Z I belive) and crank it up for the LORAN-C receiver
in the matching balun, so the feed impedance is way higher than 50Z

Mind you, I don't dispute that you may be right, I just don't think
you have data to back up your claim...

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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