[time-nuts] Active LORAN antenna

Brooke Clarke brooke at pacific.net
Fri Aug 26 21:46:08 UTC 2011

Hi Poul:

You're correct.
The noise floor for the AMRAD unit is caused by line conducted noise, 
not the background noise coming from the whip.
The DA-100 seems to have filtered out the line noise so you do see the 
I live in a jungle (forrest?) so there's not as much noise as in a city.

Have Fun,

Brooke Clarke

Poul-Henning Kamp wrote:
> In message<4E580972.6080103 at pacific.net>, Brooke Clarke writes:
>> It looks like the noise floor is maybe 10 dB higher than the AMRAD
>> http://www.prc68.com/I/Images/AMRAD_BT.GIF
>> or 30 dB higher than the McKay Dymec active antenna.
>> http://www.prc68.com/I/Images/Da100nf.GIF
> 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...

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