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[KX3] RE: Fwd: [MagLoop] 160 meter and 75 meter loop antennas?
Craig F. Simmons
Correction, a magnetic loop is Not Too Small for these bands, there is no set size for a magnetic loop antenna. Just like any other antenna, the size is governed by what frequency is being used. A loop made from 2 inch aluminum with a length of 80 feet, 24.1 feet in circumference is smaller than a Yagi or quad loop for 160 meters and it is 63% efficient. Not too bad I think. Date: Fri, Feb 7, 2014 at 10:13 PM Subject: [KX3] RE: Fwd: [MagLoop] 160 meter and 75 meter loop antennas? To: KX3@...
?
To small for these bands, but has anyone ever built a loop using one of those spring loaded sun shades for your car as the frame? ?The sun shades I am talking about are the ones you have to twist into a collapsed figure eight to store. ?It seems like that would be a very lightweight and compact solution. |
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Re: details about the Alpha loop
From: Craig F. Simmons ; To: ; Subject: Fwd: details about the Alpha loop Sent: Fri, Feb 7, 2014 3:42:25 PM
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Re: RaDAR with an Alpha Loop Antenna
I just got myself an Alpha Loop not too long ago, and find that tuning to till I hear the loudest noise floor is very easy, then I transmit and get DX results on 10 and even 1 watt! I've only found the Alpha Loop Antenna available for sale in one place though, which is here:??Great American Made product! Built to last! |
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Re: RaDAR with an Alpha Loop Antenna
Marcus NX5MK
¿ªÔÆÌåÓýSeveral HAMs are using loop antennas nearly daily (especially Greg N4KGL with AlexLoop) and having great success with them.See his and other posts on the RaDAR group (Rapid Deployment Amateur Radio): I myself just got an Alpha Loop and getting the hang of tuning a loop antenna. First QSO was from Arkansas to England (UK) with 10W SSB. Not bad I¡¯d say :) If you are interested, join in on the fun and operate your loop /P or /PM, post to the group and maybe even participate in the upcoming contest??if you like a challenge. vy 73 de Marcus NX5MK Apparare Scientior Paratus Communicare |
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Re: Pixel Loops
tomdoubts doubting
RF-PRO-1A no longer available - (VERSION-1) of the current RF-PRO-1B slight design changes - a few other component upgrades - enhancements. On Thursday, February 6, 2014 7:25 AM, "kkyahoo@..."
wrote:
?
Can any one tell me what the differences are
between the Pixel Pro-1A and the 1B?
?
Thanks
?
Kevin
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Pixel Loops
Can any one tell me what the differences are between the Pixel Pro-1A and the 1B? ? Thanks ? Kevin |
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Fw: Wow, Re: Pixel-RF-PRO-1B receive magnetic Loop
Wow, Andrew, a happy customer - and former Pixel, although he didn't identify the model, owner!
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You haven't converted me. I see one possible way... I have a similar spot in my walkup tall attic where I could mount your antenna on a five foot mast in a tripod mount, just like my existing Pixel Pro-1A, which would be ~22-25 feet away and whose loop axis would be in parallel. I'll even measure the RG-6 QS I use to insure they are the same length - except for the BNC/F adapters, which I have. I could then A-B the antennas in 'real time' on a mix of receivers, including a Drake R8, Icom R-75, JRC NRD-525, and Lowe HF-150 & 225. Both would be indoors. Unlike Guy's quantitative comparison on an SDR, mine would be a qualitative comparison. All you have to do is send me one of your antennas - gratis. Should it really best my Pixel, I will publish my findings here, as well as my recipe for the crow I would consume in such an event. Let me know if you need my address. John --- In loopantennas@..., Andrew Ikin <andrew.ikin@...> wrote:
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160 and 75 meter Magnectic loop antennas
I was wondering how much work has been done and would like to see some
discussion on Loop antennas for 75 meter and 160 meter band. I for one
have the most trouble with these two bands due things common for most
hams. No tall well spaced trees on my property. No huge type antennas,
or a way to put up long , very high wires. No huge towers to support any
of these either. I would like to reference two web locations that
discuss two type of loop antennas that seem to work very well. I plan on
making a ground mounted loop antenna for use just for 160 meters and 75
meters made out of 2" aluminum conduit with joints being welded
together and a correct size vacuum variable capacitor. see listed links.
? (3" aluminum tubing 15' transmitting magnetic loop) (80 meter 2" aluminum loop antenna) |
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Fw: Wow, Re: Pixel-RF-PRO-1B receive magnetic Loop
Below is a message received from Tim last October.
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Kind regards Andrew ----- Original Message -----
From: "Tim Harding" <sgmtim@...> To: <sales@...> Sent: Wednesday, October 16, 2013 7:03 PM Subject: Wow Hi, |
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Re: Pixel-RF-PRO-1B receive magnetic Loop
¿ªÔÆÌåÓýJohn
wrote on Feb 4,
?
?
"If
you need help in deciding between the Pixel and Wellbrook units, consider this;
BNC connectors, a la the Wellbrook unit, are not weather-rated and are most
often used with RG-58, even premium examples of which do not have 100% shield.
RG-6 Quad Shield and it's connectors have 100% shielding and are more reasonably
priced - and weatherproof. It won't matter re the weather-rated nature if you
use the antenna inside. Still, incomplete shielding in jumper cables can pick up
locally generated QRM. For that matter, the poor internal and case shielding of
your very radio, like my Palstar R30A, can pickup QRM!
I would suggest reviewing eham reviews of the antennas (Under 'Antennas: HF Vertical and Wire'.) for more unbiased opinions - as well as mine (JRT3) in the Pixel heading(4 pages) - and Guy's (4NRADIO) in both the Pixel and Wellbrook listings (2 pages). He references his comparison, available from the Wellbrook site, and gives the Pixel it's lowest rating of 3/5, the couple of 4/5 ratings highlighting the need for a rotor. The longer running Wellbrook does have fewer reviewers - and many herald the excellent customer service - but they are all 5/5 (The Pixel gets a 4.8/5!), and apparently doen't need the customer service as much. In all seriousness, they are likely very close in performance - and a poor choice cannot be made. John" ?
?
?
Hello
John,
?
Most
coaxial connectors are not "weather rated"; they require the user to do this,
either by using special tape or in Wellbrook's case using a PVC boot filled with
Vaseline;?this?makes for easy connexion and dis-connexion.
?
100%
shielded cable will have little effect on QRN because of the common mode pick-up
with unbalanced cable.? If you have an issue with common mode pick-up then
the use of common mode chokes and? 1:1 isolation transformer at the Rx can
help.
?
Also
you need to consider that the system NF is set by the loop antenna amplifier. It
highly unlikely that feeder noise pick-up would degrade the antenna, unless this
run is very long.
?
Btw,
Guys Atkins a couple years back noticed a noise issue with quad screen cable. We
didn't get to the bottom of it, but I surmised that the problem may be to do
with the use of dis-similar metals ( copper/aluminium ) for the screen i.e. any
moisture could cause electrolytic reaction resulting in noise
voltages.
?
Kind
regards
?
Andrew
? |
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Re: test
Kjell W. Strom
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Re: Pixel-RF-PRO-1B receive magnetic Loop
¿ªÔÆÌåÓýChris Trask wrote on Feb 4.
?
?
"In
my design (in the group files section) I chose a 12V supply rail as it was best
suited for direct operation from 12V batteries, such as Gel Cells, which would
take care of any concerns of power supply induced noise. The biasing of the two
stages was selected to give a decent power consumption vs. performance. At HF
frequencies the NF performance is secondary to IMD performance due to
terrestrial and galactic background noise and the presence of numerous
high-power broadcast stations.
The performance of my amplifier exceeds that of Pixel and Wellbrook, having a 2.42dB NF at 10MHz. To get better IMD performance than I attained would require a 2W or more power amplifier, which would at least double the power consumption. Using an older transistor such as the 2N3553 or a newer device such as the NE46134 in the output stage and boosting the biasing current to 100mA or so would do it. Chris" ?
?
Hello Chris,
?
Running? Pixel loops from a Wellbrook ALA1530 Antenna
Interface with a 12V dc supply makes little difference unless you are measuring
the IOP3 which only changes by a few dBm.
?
Concerning your last paragragh which you have repeated many
times. I am not aware that any one else in the group has been able to get your
design working. The NF of Pixel and Wellbrook loops is in the region of 2dB; so
I don't see an issue here. Wellbrooks ALA1530S+ Imperium has a much more
impressive IOP3 of +55dBm.
?
?
73
?
Andrew |
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Re: Pixel-RF-PRO-1B receive magnetic Loop
In my design (in the group files section) I chose a 12V supply rail as it was best suited for direct operation from 12V batteries, such as Gel Cells, which would take care of any concerns of power supply induced noise. The biasing of the two stages was selected to give a decent power consumption vs. performance. At HF frequencies the NF performance is secondary to IMD performance due to terrestrial and galactic background noise and the presence of numerous high-power broadcast stations. The performance of my amplifier exceeds that of Pixel and Wellbrook, having a 2.42dB NF at 10MHz. To get better IMD performance than I attained would require a 2W or more power amplifier, which would at least double the power consumption. Using an older transistor such as the 2N3553 or a newer device such as the NE46134 in the output stage and boosting the biasing current to 100mA or so would do it. Chris When the going gets weird, the weird turn pro - Hunter S. Thompson |
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Re: Pixel-RF-PRO-1B receive magnetic Loop
Jack,
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Thank you for your reply. You could have chosen a +10V internal rail - and a 10V regulator - but, no.... Yeah, you probably designed the amp with IM requirements - and high linearity, etc. Phooey! As my 12V 14+ A-Hr backup battery runs 12-13.2V, I guess I'll just have to 'try' it and see. It will be for emergency/loss of power, much less common in my newer home, anyway. Probably time to get out my collection of parts destined for my homebrew remote loops... if I could just find my soldering pencils... I did find my 200W iron... moving isn't fun! Thanks again! John --- In loopantennas@..., Jack Smith <Jack.Smith@...> wrote:
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Re: Pixel-RF-PRO-1B receive magnetic Loop
If you need help in deciding between the Pixel and Wellbrook units, consider this; BNC connectors, a la the Wellbrook unit, are not weather-rated and are most often used with RG-58, even premium examples of which do not have 100% shield. RG-6 Quad Shield and it's connectors have 100% shielding and are more reasonably priced - and weatherproof. It won't matter re the weather-rated nature if you use the antenna inside. Still, incomplete shielding in jumper cables can pick up locally generated QRM. For that matter, the poor internal and case shielding of your very radio, like my Palstar R30A, can pickup QRM!
I would suggest reviewing eham reviews of the antennas (Under 'Antennas: HF Vertical and Wire'.) for more unbiased opinions - as well as mine (JRT3) in the Pixel heading(4 pages) - and Guy's (4NRADIO) in both the Pixel and Wellbrook listings (2 pages). He references his comparison, available from the Wellbrook site, and gives the Pixel it's lowest rating of 3/5, the couple of 4/5 ratings highlighting the need for a rotor. The longer running Wellbrook does have fewer reviewers - and many herald the excellent customer service - but they are all 5/5 (The Pixel gets a 4.8/5!), and apparently doen't need the customer service as much. In all seriousness, they are likely very close in performance - and a poor choice cannot be made. John |
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Re: Pixel-RF-PRO-1B receive magnetic Loop
¿ªÔÆÌåÓýJohn:The loop amplifier has an on-board 13.8V DC regulator. This has an overhead of 2.2V, typical, 2.7V worst case. If you use the worst case for regulator and overhead plus internal voltage drop in components ahead of the regulator, the MINIMUM DC voltage measured at the output jack on the loop amplifier is 16.8V.? As a designer, I have to use the worst case or else risk having some unacceptable level of failure to operate. If the supply voltage is below this value, correct operation cannot be guaranteed. In the best case with 12V, it will sort of work, but none of the specifications will be met.? Maybe that will be OK under some conditions, but the internal voltage regulator will drop out of regulation. The particular regulator used will "try" to maintain the output voltage at 13.8V, but with only 12V on the input, it will obviously fail. When these regulators are operated with lower input voltage than the defined output, they have a 1 to 2V drop, so the loop amp will see 10 or 11V on the internal "regulated" supply rail and as I said all performance data is based on 13.8V, so performance will be degraded. Jack K8ZOA On 2/4/2014 9:36 AM, John wrote:
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Re: Pixel-RF-PRO-1B receive magnetic Loop
Jack,
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Doug Talley of Pixel told me that the amp would work with a dedicated 12V power inserter when I contacted him re the improvements of the 1B loop over my 1A. After sending him pictures of my late 1A and it's amp, he determined it to be the then later variant. I guess my question is simple - will my Pro-1A work with a dedicated 12V negative ground power inserter for 'emergency' - or portable - use? I have appropriately sized diecast cases, connectors, etc, and some 1-10 mH rf chokes rated at several hundred mA, too. I should have taken him up at the time on his free offer - at least I'd no. Perhaps, as the designer of the preamp, Jack, you might comment on the suitability of this. If the bias will be way off - and the gain suffers - perhaps we'll look for a 'Plan B'! John --- In loopantennas@..., Jack Smith <Jack.Smith@...> wrote:
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RES: Pixel-RF-PRO-1B receive magnetic Loop
¿ªÔÆÌåÓýHuuum! What are you comparing in the pdf review is not really the same antenna¡ ? ? De: loopantennas@... [mailto:loopantennas@...] Em nome de Dominique Kremp ? ? Hi folks, ? Just have a look at this review from Guy Atkins: I fully agree with him ! ? Dominique Normandy, France ? ? De?: loopantennas@... [mailto:loopantennas@...] De la part de dstremme@... ?
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