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

Alan Melia alan.melia at btinternet.com
Thu Oct 22 16:23:30 UTC 2009


Hi Bert oh well commiserations I don't have that problem. With LF you don't
actually need a clear sight and takeoff. like at higher frequencies. The
wavelength of 60kHz it so big is goes round buildings without any trouble.
(It will actually penetrate seawater to some extent though not as well as
NAA on 24kHz) The loop should work just as well in your back lot. and you
can probably get better spacing from the domestic noise sources??  Also
height is not too important either though they are better at least a few
feet off the ground to reduce the coupling to the lossy ground.

Alan G3NYK


----- Original Message -----
From: <EWKehren at aol.com>
To: <time-nuts at febo.com>
Sent: Thursday, October 22, 2009 4:10 PM
Subject: Re: [time-nuts] Adret 4101A, the DCF77 and a good antenna


> Alan, my problem is it has to look half way decent and be acceptable to
the
>  neighbors, one time I had to take down a HP Loop for 60 KHz. Did not fit
> the  esthetics of the home fronts and only the front faces Boulder. I once
> tried  forming plastic pipe by heating it with a heat gun while wrapping
it
> around an  oil barrel. Still not perfect.
> Bert
>
>
> In a message dated 10/21/2009 8:03:07 P.M. Eastern Daylight Time,
> alan.melia at btinternet.com writes:
>
> Hi Bert  yes it makes a good "former" if you have it.  I bent some stiff
> wire
> (fence wire ?) into a loop of the right size, insulated the ends so it
> didnt
> form a "shorted turn" and tiewrapped the multiway cable to  that.......not
a
> s neat as your method. The point I was making is that the  (Faraday)
> screening doesnt buy you much, if anything, at these very low
frequencies.
> It is a very different story higher up the spectrum.
>
> I  looked at 1in. white water pipe but it is not easy to form into a loop
> :-))  For smaller loops I used hoola hoops from Toys R Us....there is a
> plug
> holding them together which is easily removed then I jouned the ends  with
a
> 1in "T" piece and glued that into a plastic box (lots of hot melt  to
> water-proof it ......I hope!) where I made the connections to form  itinto
a
> mutiturn loop.
>
> Best wishes
> Alan G3NYK
> ----- Original  Message -----
> From: <EWKehren at aol.com>
> To:  <time-nuts at febo.com>
> Sent: Wednesday, October 21, 2009 1:53  PM
> Subject: Re: [time-nuts] Adret 4101A, the DCF77 and a good  antenna
>
>
> > Alan,
> >  I used a copper pipe because it is  the easiest way to make a round
> loop.
> > I have also used PVC but  it always ended up rectangular. If you have a
> > better idea please let  me know, because I am considering to fire up my
> old
> > Tracor 599  receiver that I modified to work up to 80 KHz. Used it a
long
> time  on
> >  60 KHz.
> > Bert Kehren     WB5MZJ
> >
> >
> > In a message dated 10/21/2009 5:19:28 A.M.  Eastern Daylight Time,
> > alan.melia at btinternet.com  writes:
> >
> > Hi  Magnus I was not sure whether the 4101A would  go up that far. I had
> not
> > noticed the news about HBG.  That is  a disappointment,  particularly
with
> > the
> > number of "radio  clocks" around in "domestic" use,  and from the "Land
of
> > Clocks"  too.
> >
> > Someone mentioned a screened loop  in copper pipe.  Screening loops at
> this
> > frequency gives little advantage  and the  extra stray capacitance can
> > degrade
> > the performance. An open  loop  works just as well (and is much easier
to
> > build for a  trial) the problem  usually comes from common mode pick-up
on
> >  the
> > feeder to the receiver. This  is often best combatted by  careful
> balancing,
> > or transformer  isolation.
> >
> >  Alan G3NYK
> >
> > ----- Original Message -----
> > From:   "Magnus Danielson" <magnus at rubidium.dyndns.org>
> > To: "Discussion  of  precise time and frequency measurement"
> >  <time-nuts at febo.com>
> > Sent:  Wednesday, October 21, 2009  1:30 AM
> > Subject: Re: [time-nuts] Adret 4101A,  the DCF77 and a  good antenna
> >
> >
> > > Alan Melia wrote:
> > >  >  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.
> >  >
> > > The TDF 162 kHz is a 2 MW transmitter which is  even  closer...
> > >
> > > A bit tricker to retriev the timing  signal  thought, but this is
> assuming
> > > the signal can be  freely  selected.
> > >
> > > The HBG transmitter is going  off-air (for good) in a  not to distant
> > future.
> >  >
> > > Cheers,
> > >  Magnus
> > >
> > >  _______________________________________________
> > >  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.
> >
> >
> >  _______________________________________________
> > 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.
>
>
> _______________________________________________
> 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