Wellbrook loop resistance?

Useful information regarding antennas for SDR products.
octave9
Posts: 59
Joined: Sun Feb 19, 2017 7:54 pm

Wellbrook loop resistance?

Postby octave9 » Sun Mar 05, 2017 7:30 pm

My friend's Wellbrook loop isn't working and we're trying to work out if the whole thing is kaput, or just the power unit. His is the aluminium outdoor one and he reads 815 ohms. Mine is an indoor type and the resistance is much higher at 3.15k and working well. He gets 12v negative on the BNC inner, if the loop isn't connected, which is opposite to mine, and blows a fuse if powered up with the loop connected. The 1N4004 reverse polarity protection diode was o/c.

I saw a few posts about them here and wondered if anyone knows what theirs is, or knows where the info can be found.

Thanks.

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g1hbe
Posts: 216
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire

Re: Wellbrook loop resistance?

Postby g1hbe » Sun Mar 05, 2017 9:05 pm

The inner of the BNC should definitely be positive 12v. Resistance-wise I get 1.4 Mohm, but the reading probably varies depending on what voltage your meter runs from. Looks like your friend's interface unit has had some reverse polarity!

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Andy

octave9
Posts: 59
Joined: Sun Feb 19, 2017 7:54 pm

Re: Wellbrook loop resistance?

Postby octave9 » Mon Mar 06, 2017 7:17 pm

Turns out his needs -ve on the inner PSU connection! Pretty unusual and opposite to mine. It seems to have survived reverse polarity. Thanks.

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