Re: 7.5ā€ Loopstick LW antenna not enough inductance?


Steve Ratzlaff
 

Curious, I unsoldered my R33 LF coil and measured it--1546 uH at 100 kHz test frequency--so mine isn't close to 1700 uH either, yet mine will tune down to at least 200 kHz with my PL 380 ULR. Here in USA there are no LWBC stations to be heard so I try for NDBs, which only go down as far as 198 kHz (DIW in North Carolina, a powerful NDB).

So I guess your R33 rod has even less permeability than mine, and the 1432 uH is probably correct. If you can rewind it with more turns, that's what I'd suggest doing. It wouldn't matter if turns on the end were under the rod support, that wouldn't affect the rod's pickup.

73,

Steve AA7U

On 8/22/2019 9:58 AM, igvitk@... wrote:
Hi all! Iā€™m trying to make the 7.5ā€ loopstick LW antenna according to the instructions. I used the Amidon R33-050-750 rod, 100/44 litz wire, made 122 turns of the coil, which is located exactly in the center of the rod and which length is 106,5 mm. However, the output inductance measured by the multimeter is only 1432 uh instead of 1700 uh. The similar result was shown by another multimeter VICY DM4070. I think that is a strong deviation. Can anybody help to resolve this problem?

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