Try to get a DA-100 with a socket for the FET along with some spare FETs.
The FETs are very hard to get but a sub will work if strong local
signals are absent.
On 08/26/2011 02:46 PM, Brooke Clarke wrote:
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
background.
I live in a jungle (forrest?) so there's not as much noise as in a city.
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/
Poul-Henning Kamp wrote:
In message<4e580972.6080...@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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Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430
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