----- Original Message -----

Sent: Wednesday, December 25, 2002 10:12 AM

Subject: LF: Loops once more

Hello all ,

Here follows my experience with a big loop:

I have a small loop with 40turns, the turns are spaced 5mm and the side of the loop is 70x70cm. The wire has a diameter of 1mm. The inductance is 1.85mH and the Q is 110. Together with this I use a modified version of the preamp described on page 30 in the LF Experimenters Handbook. The main difference being BF246C (high current FET:s) used instead of 2N3819.

The directivity is as follows: When adjusted to get maximum signal from DCF39 I have about S9+30dB on the S-meter (on a DRAKE TR7) dropping to around S7 when adjusted to get minimum signal from DCF. (I have no means of calibrating the S-meter accurately).

Last summer I tried a bigger loop with 6 turns and a side of 5m. It was mounted with the lowest corner about 50cm above ground and using the same preamp as described above. The wire used was with a cross section of 1,5mm2 and having plastic insulation.

It was then turned to get a peak on DCF39. Changing between the two loops a few times revealed that the big loop was just slightly better than the small loop. The difference was barely detectable on the S-meter. I did not measure the Q, however when adjusting for resonance I found that it was not that "sharp" as that of the small loop so the Q seems to be lower. The inductance was around 1mH. Considering the small difference to the samll loop and the problem of turning it I soon took it down.

Merry Christmas and a Happy New Year

Hello Urban.

Thanks for your reply and the only one so far that has answered my Question properly.

Happy New Year

de Mal/G3KEV

SM5EUF / Urban