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

EWKehren at aol.com EWKehren at aol.com
Wed Oct 21 02:49:25 UTC 2009


Good morning Marco
In the past I had best luck with a loop antenna using a copper tube (one  
end insulated) using as many turns as I was able to run through it and tuning 
it  to frequency. One can also use a multi conductor cable and spice the 
ends in  such a way that it becomes a multi turn loop. I used a two stage pre 
amp split  in two parts one in the antenna so that there was no AC/DC 
decoupling, the coax  did the RF and power.
Bert Kehren WB5MZJ
 
 
In a message dated 10/20/2009 10:27:41 P.M. Eastern Daylight Time,  
wb6bnq at cox.net writes:

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
>
>  _______________________________________________
> time-nuts mailing list  -- time-nuts at febo.com
> To unsubscribe, go to  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the  instructions  there.


_______________________________________________
time-nuts  mailing list -- time-nuts at febo.com
To unsubscribe, go to  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the  instructions there.





More information about the Time-nuts_lists.febo.com mailing list