In article
,
Joe Analssandrini wrote:

Dear "Telamon,"

It really is true - Ibiquity bought a large number of Wellbrook ALA
1530 antennas (I'm not sure in which of the various incarnations of
the '1530 they were) as they found that this one was the most reliable
and consistent antenna for them to use when testing AM IBOC. (Please
note that I am NO fan of "digital" MW or SW [AM] in ANY form!) Their
order was so large that Andy Ikin was forced to delay individual
orders that came in after the Ibiquity order; he is only one person
and there are still only 24 hours in a day! I understand that it took
him several months to catch up.

This does not surprise me that Ibiquity bought these antennas. I just
don't go along with RHF's off base assertion. I'm sure it was the small
size where it could be easily mounted at a good height, the antennas
gain, and rejection of local noise that compelled them to purchase these
antennas because as we all know the digital signals are low power.

I cannot comment on the performance of any of the ALA 1530 range,
having never owned one nor have I even personally known anyone who
does; I can only comment on the performance of the Wellbrook ALA 330S
(the shortwave-primarily model) of which I do own two (one used with
my Grundig Satellit 800 and the other with my AR7030 Plus). It is
overall the best antenna I personally have ever used in fifty years of
shortwave listening. (Though I am sure that I have not used as many as
you - or many others here - have, I have had a 300-foot wire, a 100-
foot wire, several active antennas, and several whip-type antennas,
both active and passive, over the years.)

I would just like to mention another advantage of the Wellbrook
(small) loop antennas over the (large loop) antenna you suggested (I
think you may have touched on this in a later post) and that is the
fact that a small loop will be most sensitive to the magnetic portion
of the radio signal and will reject the electrical portion. This, of
course, is the exact opposite of what a large loop will do. In other
words, the small (amplified and well-shielded) loop will reject local
electrical noise as well as atmospheric noise (especially in the
summertime) whereas the large loop, like any large wire antenna, will
pick up these extraneous interferences. In a community in which people
live close together, such as my own situation, a large passive loop
antenna just would not do. Only a small loop will perform in a
satisfactory method assuming it is well-designed and well-made.

I can't argue with you about the fact that the smaller loops have better
local noise rejection over the larger loops but once any distant signal
or noise propagates as a far field the energy is divided between the
electric and magnetic fields. The electrically small loop will pickup
the atmospheric noise just as well as the larger loop. However, you may
hear less atmospheric noise on the small loop because the amplifier is
bandwidth limited, which will further limit the noise.

Rotating a loop is also important in a situation such as mine in order
to null out any especially pernicious noise; the Wellbrook ALA 330S
has a very sharp null. (The null point is exactly the opposite of a
large loop - 90° away - but I'm sure you already knew that.) Having
two Wellbrooks for one receiver at 90° positioning would not be
satisfactory (even if that option were affordable!) though it probably
is fine for large loops, which are not quite as directional.

I would hope to get the small loop up high enough to avoid the local
noise and not have to rotate it. If that didn't work out then the rotor
would be tried next.

If it hadn't been for the Wellbrook AA 330S and its rotatability and
its rejection of local electrical noise, I would have had to abandon
the hobby!

We all have our cross to bear when it comes to local noise. What is
important is you found a working solution.

P.S. The small, amplified, Sony AN-LP1 Active Antenna, though not even
in the same ballpark as the Wellbrook ALA 330S, nonetheless is the
best affordable loop antenna I have found for use with portable
shortwave radios, the Eton E1, Grundig Satellit 800, Drake SW-8, and
several Lowe portables excepted. The AN-LP1 provides a good,
relatively quiet, signal and does not cause overloading on most good
compact portable shortwave receivers. While rotating it is cumbersome
at best, it can be done if necessary. It's great for taking on trips
as well.

Well, even a small loop with minimal amplification is better than a whip
antenna unless you are at the park running on batteries.

--
Telamon
Ventura, California