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: <ewkeh...@aol.com> To: <time-nuts@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.me...@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" <mag...@rubidium.dyndns.org> > To: "Discussion of precise time and frequency measurement" > <time-nuts@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@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@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@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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
