Ron Hardin wrote:
wrote:
I have the ANC-4 (original JPS version), which was a great help with
random wire antennas. It seems to be of no use with my welbrook. I
tried to use the built-in noise antenna on the ANC-4 to make a null
with my Wellbrook and never managed to get that to work. Of course,
the Wellbrook is a very quiet antenna in the first place.
It works fine with mine, using a wellbrook ala1530 and an active whip
(or another wellbrook 1530).
I don't think the built-in noise antenna is likely to work though.
I tossed mine out.
With a wellbrook loop and a whip _located right near it_ (near means
fraction of a wavelength), you get the same pattern as with two
whips separated by a quarter wavelength, but without using any
real estate, laid out in the plane of the loop, ie. a double null
at one endfire and a max at the other endfire, opening up to a V
and sweeping to a double null at the opposite endfire and max at the
other.
Two loops separated by a quarter wavelength are handy for some things,
like nulling in advance a particular station, and then nulling another
altogether with the ANC-4, without having to go to multiple ANC-4's.
There is an odd thing with two loops, though.
For nulling a station by phasing, paradoxically, you should put the
station near the max of the loop, not the null. The phase of the
signal from the loop gets more and more unstable as you approach the
loop's null, and harder and harder to phase out with the ANC-4, is
the reason. It's comparatively easy near the loop's max.
--
Ron Hardin
On the internet, nobody knows you're a jerk.
I've been experimenting some more with the ANC-4 / H-800 combination. I
now have the H-800 situated in a nice spot outdoors, and have noticed
something odd when it comes to eliminating noise. As soon as I turn on
the ANC-4, using the H-800 as the noise antenna, the noise is often
already minimized. For example, the noise level might immediately drop
from S6 to S3, and adjusting the noise gain and noise phase controls
will have little effect (good or bad) on this S3 noise level. This
doesn't happen everytime, but it happens a lot...most of the time.
If I then use a wire as my noise antenna, the noise level might drop
one or two S units as soon as I turn the ANC-4 on, but it takes some
knob twiddling to get the noise level down to the S3 reading that I get
automatically and immediately when using the H-800. And the best result
using the wire is always the *same* as the result I get straight away
using the H-800. Always.
I've puzzled over why this is. I think it must have something to do
with the fact that the H-800 has quite a bit more gain than the wire,
making it a better 'match' for the main antenna...which means a lot of
the work is done for me? This is just a guess.
Similar Threads
Question about the Timewave ANC-4
Threaded Mode
