[time-nuts] Adret 4101A, the DCF77 and a good antenna
Alan Melia
alan.melia at btinternet.com
Wed Oct 21 23:00:39 UTC 2009
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
> >
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