--- Begin Message ---
- Subject: phased antennas (was: Help with a couple UNIDs)
- From: Mark Connelly <markwa1ion@xxxxxxx>
- Date: Mon, 22 Dec 2014 22:37:16 -0500
- Delivered-to: irca@xxxxxxxxxxxxxxxx
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This discussion reminds me of the progression of car-DX antennas I've
deployed at seaside DXpeditions over the years:
(1) Early '70s: the car's vertical
Omnidirectional; broadband
(2) Mid/late '70s: vertical through FET regenerative tuner
Still omni but huge gain boost; narrow band
(3) Late '70s / early '80s: ferrite loop (Varactor tuned, controller in
car)
Figure-of-8 pattern, rotatable; narrow band
(4) '80s: tuned or broadband vertical phased against tuned loop (=
SIMILAR TO BRIAN'S SET-UP)
Choice of omni or rotatable cardioid or rotatable figure-of-8; narrow
band
(5) '90s: broadband whip phased against broadband loop
Choice of omni or rotatable cardioid or rotatable figure-of-8; nulls
hold up over about 400 kHz of bandwidth
(6) post-2000: terminated (Flag-type) broadband loop
Configurable as cardioid or figure-of-8; broadband null
See http://www.qsl.net/wa1ion/loop/car_roof_loop.htm
The typical 25 dB null of the terminated broadband loop can be deepened
by phasing against an active whip but at a cost of null bandwidth.
Arrays such as used by Neil Kazaross, Dallas Lankford, W8JI / DX
Engineering et al. are the ultimate power tool for wide nulling. Those
require a substantial amount of land.
Mark Connelly, WA1ION
South Yarmouth, Cape Cod, MA
<<
Neil,
I seem to get a fairly stable rotatable cardioid pattern. This is most
obvious when I have two stations nearly opposite one another and can
rotate
the loop 180 degrees to go from a peak on one to a peak on the other,
then
can flip the "invert" switch on the phaser to go right back to the first
station.
I hadn't really tested the broadband aspect of the phaser null up until
now, but I did this evening. Indeed, the null holds up reasonably well
between 680 KNBR and 810 KGO. But, I have to say that I wasn't getting
the
greatest of nulls with either of these. I'm not sure if that had to do
with conditions or what else. In any case, with a tuned loop and a
tuned
vertical, I have to twiddle knobs to go from one to another. I need to
test this some more.
I have found that for strong signals, the Q is a bit too sharp on the
pre-selector so I get some leakage through the null from several kHz on
either side of the carrier, especially on lower frequencies. The
pre-selector is noticeably sharper than my loop.
Brian
On Sun, Dec 21, 2014 at 8:47 AM, neilkaz <neilkaz@xxxxxxxxxxxxx> wrote:
OK that setup should work well and be quite versatile. Are you
getting a
true cardioid pattern or at least something close that can be
adjusted and
aimed as you rotate the loop, perhaps required some retweaking?
How broadbanded is the back null? ie lets say you null out KNBR to
your
NW, is KCBS in a deep null with the same phaser setting? What about
KGO? Is
a little phase and amplitude balance tweaking needed or a lot to
switch
from best null of KNBR to a decent null of KGO?
Glad to hear that you don't have a big noise issue on your
recordings. 73
KAZ
-----Original Message-----
>From: Brian Rachford <azswdxing@xxxxxxxxx>
>Sent: Dec 21, 2014 8:54 AM
>To: Mailing list for the International Radio Club of America <
irca@xxxxxxxxxxxxxxxx>
>Subject: Re: [IRCA] Help with a couple UNIDs
>
>Wow, that was really good! With your tip, I was finally able to
pick out
>"Escucha, eckes-eh-hay-elay" at the beginning and "Navajoa, Sonora,
Mexico"
>near the end of the clip. That's certainly not what I heard at
first, but
>I can agree with that now. I hadn't thought too much about hearing
issues,
>but I know that I'm a little weak on voices and pretty good with
music.
>
>Oh yeah, I'm using a Quantum Phaser with a 6-foot tuned loop and a
23-foot
>vertical. The latter is run through an MFJ amplified pre-selector.
This
>is a new setup that is working well.
>
>Thanks,
>
>Brian
>
>
>On Sat, Dec 20, 2014 at 10:33 PM, neilkaz <neilkaz@xxxxxxxxxxxxx>
wrote:
>
>> 1270 is 100% for sure XEGL Navajoa per call ID's and Navajoa and
Navajoa
>> Sonora Mexico ments.
>>
>> My ears while very good with spoken word (especially male) are
very bad
>> with singing (almost hopeless if female) (was certified 2/3 tone
deaf
when
>> 5 years old) and I copy nothing on 1450 that is calls.
>>
>> What are you phasing that loop against? What loop? What phaser?
>>
>> 73 KAZ
>>
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