wrote:

I have this vision of the loop snapping off at the base (standard
mounting) when it's loaded with ice in a high wind. It's not clear to
me
how you would provide more vertical support at the top of the loop
without interfering with it's ability to rotate (with a rotor).

Well, it isn't always mounted on a rotor. I didn't use a rotor because
the antenna's performance seems pretty omnidirectional on the
frequencies that interest me. However, I don't spend a lot of time on
MW either, and anyone who does should definitely use a rotor.

My sense is that the antenna is quite strong and there's nothing on it
to really 'catch' the wind. If you didn't provide additional support, I
doubt that the antenna would ever sustain wind damage. However, if you
had it right in front of you and had an hour or two to think about it,
I'm sure you could improvise some sort of additional support. You'd
probably have fun doing it, too!

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.

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.

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.

"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.

And any competent electronics outfit has already done so, if they were
interested in the design.

I've worked for numerous firms over the years and the number of competitor
products coming through the door for study and evaluation was astounding.

If it hasn't been mentioned already, there was a review in the 2002 Passport
regarding this antenna and the dual axis rotor scheme by Chuck Rippel. It may
have appeared in other additions as well.

dxAce
Michigan
USA

"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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starman wrote:

"Mark S. Holden" wrote:
snip
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.


I suppose if you're serious about chasing DX the cost of a dual axis rotor
system would be small compared to the money you could toss at a radio upgrade.

Personally, I think it would be slick to do a dual axis rotor system with a yagi
for radio astronomy.

Mark S. Holden wrote:
starman wrote:

"Mark S. Holden" wrote:
snip
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.


I suppose if you're serious about chasing DX the cost of a dual axis
rotor
system would be small compared to the money you could toss at a radio
upgrade.

Personally, I think it would be slick to do a dual axis rotor system
with a yagi
for radio astronomy.

I'd say that if you're chasing MW DX the rotor is an absolute 'must
have'; but I wouldn't say this where SW DX is concerned. I was sort of
hoping that the antenna would have directional characteristics above,
say, 4500 khz; but it sure doesn't seem to, at least in my location and
listening conditions. I guess I'll just have to resign myself to an
excellent omnidirectional antenna... .

Steve

"Mark S. Holden" wrote:

Personally, I think it would be slick to do a dual axis rotor system with a yagi
for radio astronomy.

That's the ticket!