"Mark S. Holden" wrote:

starman wrote:


One of the nice features of the Wellbrook is being able to mount it with
a dual axis rotor so you can fine tune the reception angle. It's an
expensive option but that's what I would do to get the most out of it. I
wonder if anyone knows the circuit design for the loop's pre-amp? That's
probably what makes it perform so well.

The Wellbrook preamp is potted to make it tougher for someone to swipe
the design.

That's a challenge I would enjoy. Anyone want to donate their Wellbrook
loop preamp for micro-disection?

I think major reasons it performs so well include the fact loop antennas
are less susceptible to noise, and they were able to design their
antennas as complete systems.

If you'd like to experiment with preamps, I suggest checking ebay or
your local hamfests for preamps made by companies like Avantek, WJ, or
the company known at various times as Norlin, Aiken, ACL, and Applied
Communications. Typically, they'll be low noise designs with plenty of
dynamic range. I often find these at the flea at MIT for anywhere
between $10 and $40.

I also tried an ARR brand preamp, (about $50 new) and it performed well,
but it got taken out by the first lightning strike in the neighborhood.

As for being able to rotate the Wellbrook loops, my understanding is
you're not likely to notice a difference on HF bands.

I thought so too but I've seen of reports to the contrary.


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