[time-nuts] Adret 4101A, the DCF77 and a good antenna

Alan Melia alan.melia at btinternet.com
Tue Oct 20 23:16:55 UTC 2009


Marco, have you considered that HBG on 75.0kHz might be stronger with you
from Switzerland??. In a lab or other complex quite often with off-air
standards the problem is local noise. I have a friend in Porto who used to
be able to lock to MSF when it was at Rugby a few years ago.......I havent
asked since it moved north to Anthorn but I suspect he uses GPS now. If the
noise is not a problem these receiver will often work well on a resonable
wire antenna which is fairly easy to rig. Or see the PA0RDT MiniWhip design
for a very simple active low frequency antenna. This is used all round the
world for receiving weak amateur signals on 136kHz ....it is broadband up to
about 500kHz, and down to 40kHz Japanese frequency standard transmissions.
It is so small you can experiment to find the best quiet position. At LF the
secret is the higher the better.

Alan G3NYK


----- Original Message -----
From: "Marco A. Ferra" <maferra at gmx.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Tuesday, October 20, 2009 10:27 PM
Subject: [time-nuts] Adret 4101A, the DCF77 and a good antenna


> Hey time-nuts people,
>
> First of all, let me start by saying that I follow the time-nuts mailing
> list for some time and it's a great source for trading experiences.
Perhaps
> you can help me on this one.
>
> We have in our laboratory, in Portugal (near Lisbon), an Adret 4101A
> Frequency Receiver Standard, and we are trying to pickup the DCF77 signal
> from Frankfurt, Germany.  I wasn't sure if the unit was working properly
(it
> seems quite old), but by injecting directly a 10mV 77,5 kHz sinusoidal
> signal in the BNC antenna input I got the "level" and the "locked" green
> leds to lit (it seems good news).
>
> However, I believe that the DCF77 arrives very weakly in Portugal, and I
> thought on constructing a passive or active, but very simple antenna to
> connect to the Adret 4101A.
>
> Do you have any experience on this equipment (we don't have the manual,
just
> a brochure with a few pages [1]), the DCF77 signal itself or an ideia for
a
> antenna that could be very sensitive to this signal?
>
> Kind regards, and thank you in advance,
>
> [1]
>
http://www.adret-electronique.fr/appareils_adret_metrologie/4101a/4101a.pdf
>
>
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