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

[WB6BNQ]

Hi Marco,

That looks like a really nice receiver.  It is a little numb as far as
sensitivity goes, but there are reasons for such.  At those low frequencies
atmospheric noise will certainly be quite high.  So, one way to to handle it is
to put the signal preamp out at the antenna, usually a magnetically shielded loop
similar to the loop used with the Hewlett Packard 60 KHz receiver loop antenna.
The loop also acts as an extremely narrow filter.

I wonder if the manufacturer still exists ?  If so maybe they could be of help as
they may still have parts and hopefully their active loop antenna that went with
that receiver.

Otherwise, you would have to build your own antenna.  I highly suggest looking at
designs on the WEB, as others have suggested, concerning magnetically shielded
loops as they help with rejecting local noises.

Good luck with your project !

Bill....WB6BNQ


"Marco A. Ferra" wrote:

> 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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