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~ ~ K9AYK9AY Loops ~ Loops ~
Thanks Gary Breed, K9AY!Thanks Gary Breed, K9AY!
de N4GG
© Harold E. Kennedy, 2008
More than you wanted to More than you wanted to know?know?
What is a K9AY loop?What is a K9AY loop? How well do they work?How well do they work? DemoDemo How to make oneHow to make one Build & test your own matching Build & test your own matching
transformertransformer What’s Important and What Isn’tWhat’s Important and What Isn’t Grounds, Ground, LocationGrounds, Ground, Location Make vs. BuyMake vs. Buy
HistoryHistory ““The K9AY Terminated Loop-A Compact, The K9AY Terminated Loop-A Compact,
Directional Receiving Antenna,”Directional Receiving Antenna,” QSTQST, Sept. , Sept. 19971997
Performance varied: Great, Fair, PoorPerformance varied: Great, Fair, Poor Most had 60 Hz humMost had 60 Hz hum
Hum problem resolved, Hum problem resolved, QST,QST, May, 1998 May, 1998 Binocular matching transformers Binocular matching transformers
replace autotransformers ~ 2001replace autotransformers ~ 2001 Commercial versions begin ~ 2001Commercial versions begin ~ 2001
AYL-4R contains grounding & layout issuesAYL-4R contains grounding & layout issues
A K9AY Loop BenefitsA K9AY Loop Benefits Significant SNR improvement over TX Significant SNR improvement over TX
antennas on 160 & 80antennas on 160 & 80 Okay on 40, useful from 300 KHz to 30MHz Okay on 40, useful from 300 KHz to 30MHz
if you home-brewif you home-brew Steerable null (QRN, QRM, Local Noise)Steerable null (QRN, QRM, Local Noise)
Front lobe VERY broadFront lobe VERY broad Best LF receive performance for the sizeBest LF receive performance for the size
11 λλ Beverage = 550 feet Beverage = 550 feet K9AY = 30 ft long, 25 ft high, single K9AY = 30 ft long, 25 ft high, single
supportsupport
Elevation Pattern - High Elevation Pattern - High Angle NullAngle Null
Azimuth Pattern – Typical Azimuth Pattern – Typical CardioidCardioid
At elevation = 61 Degrees
K9AY – Basic RF DesignK9AY – Basic RF Design
Rg - Ground Impedance - Unavoidable
Rterm9:1 XFMR
CAREFUL Design to minimize inter-winding capacitive coupling
Receives from XFMR end
Directional K9AY LoopDirectional K9AY Loop
Small Size
Termination and feed at the same location
Typical InstallationTypical Installation
Typical Stand-Alone Typical Stand-Alone InstallationInstallation(N4GG’s is in the woods – Tree (N4GG’s is in the woods – Tree limb support)limb support)
Gain, F/B, RDFGain, F/B, RDF
Do I need to understand this Do I need to understand this stuff? stuff? No - Just put one upNo - Just put one up
Very Short Course Follows…….Very Short Course Follows…….
Forward GainForward Gain
Not importantNot important Required Gain:Required Gain:
Enough to overcome common mode Enough to overcome common mode spurious signal incursion and spurious signal incursion and preamp noise floorpreamp noise floor
After that – who cares?After that – who cares? K9AY: -23 dBi @ 1.8 MHzK9AY: -23 dBi @ 1.8 MHz 11λλ Beverage: -11 dBi @ 1.8 MHz Beverage: -11 dBi @ 1.8 MHz
Front-To-BackFront-To-Back
Useful for improving SNR by Useful for improving SNR by applying a null to:applying a null to: QRNQRN QRMQRM Local NoiseLocal Noise
RDF (Receiving Directivity RDF (Receiving Directivity Factor)Factor)
Figure of merit for comparing Figure of merit for comparing receiving antennasreceiving antennas
RDF = Forward gain minus RDF = Forward gain minus hemispherical average gainhemispherical average gain
General idea: General idea: If we are skywave noise limited, then the If we are skywave noise limited, then the
more sky we can null, while we have our more sky we can null, while we have our antenna pointed at the signal, the better antenna pointed at the signal, the better off we are.off we are.
Said differently, less sky = better SNRSaid differently, less sky = better SNR
This is important
3D Antenna Pattern – Single 3D Antenna Pattern – Single VerticalVertical
Source: ON4UN’s Low Band DXing
Typical Transmit Vertical
3D Antenna Pattern3D Antenna Pattern2 Vertical Array Fed in 2 Vertical Array Fed in
QuadratureQuadrature
Source: ON4UN’s Low Band DXing
Similar to K9AY
Performance ComparisonPerformance Comparison@ 1.825 MHz in dB@ 1.825 MHz in dB
AntennaAntenna RDFRDF F/BF/B
Vertical OmniVertical Omni 5.0 0 5.0 0
½ ½ λλ Beverage 6.5 Beverage 6.5 30 @ 18°30 @ 18°
EWE, Flag, Pen’t 7.0 – 7.4EWE, Flag, Pen’t 7.0 – 7.4 Varies Varies widelywidely
K9AY 7.5 – 7.7 K9AY 7.5 – 7.7 28 @ 28 @ 60°60°
1 1 λλ Beverage 10.1 Beverage 10.1 29 @ 18°29 @ 18°Source: N4GG
Demo* – K9AY LoopDemo* – K9AY LoopAt N4GGAt N4GG
*DVD Demo in separate file
Array Solutions AYL-4R Array Solutions AYL-4R
OutsideOutside
NEMA Style NEMA Style PLASTICPLASTIC Box – Lowe’s Box – Lowe’s 4 ft Ground rod or better – Lowe’s, R. 4 ft Ground rod or better – Lowe’s, R.
ShackShack Transformer, termination resistor, SO-Transformer, termination resistor, SO-
239239 For two directions – DPDT Relay and For two directions – DPDT Relay and
85 ft wire loop85 ft wire loop For four directions – two relays & two For four directions – two relays & two
loopsloops Handy tree or Handy tree or non-metallicnon-metallic support support
AYL-4R or Home BrewAYL-4R or Home Brew
AYL-4R or Home BrewAYL-4R or Home Brew
K9AY’s Original Home-K9AY’s Original Home-BrewBrew
N4GG’s Home-BrewN4GG’s Home-BrewLooks Awful – Works Great
Ferrite beads on coax
Ferrite beads on control cable
Occasional Maintenance Occasional Maintenance IssueIssue
Original QST DesignOriginal QST Design
Autotransformer and three grounds tied together introduce common mode signals & noise, AC relay current through the autotransformer introduces
hum
DON’T BUILD THIS!
Constructed ProperlyConstructed ProperlySource: ON4UN LB DXing
AYL-4R Single Ground AYL-4R Single Ground ApproachApproach
AYL-4R Questionable Grounding
AYL-4R Outdoor UnitAYL-4R Outdoor Unit
Terminating R & RelaysNEMA Enclosure
Direction Switching RelaysMatching Transformer
Looks Nice! Grounding not optimum..
Ground loop
Suggested AYL-4R ModsSuggested AYL-4R Mods
Drill a hole herefor control lines
Use this as a drain hole only
Break the ground loopper the instructionmanual
Add ferrite beadsTo break the controlline ground loop
InsideInside
Enclosure, LEDs, Switch, DiodesEnclosure, LEDs, Switch, Diodes Receiver protectorReceiver protector
Antenna can deliver big signals Antenna can deliver big signals – lightening, transmit capture– lightening, transmit capture
Preamp (maybe)Preamp (maybe) Bandpass filter (maybe)Bandpass filter (maybe)
N4GG Home-Brew N4GG Home-Brew Control BoxControl Box
N4GG Home-Brew N4GG Home-Brew Control BoxControl Box
Receiver Protection
RF Path @ N4GGRF Path @ N4GG
To Receiver
InsideOutside
Preamp(Optional)
Limiter(Optional)
BPF(Optional)
Suggestions Only
W3LPL
DXE RPA-1Or W7IUY
ICE 196
What’s ImportantWhat’s Important
Non-conductive support (tree limb Non-conductive support (tree limb is fine)is fine)
Max distance from vertical antennas Max distance from vertical antennas and from resonant antennasand from resonant antennas
Isolated signal return and antenna Isolated signal return and antenna groundsgrounds Control line ground might need Control line ground might need
isolation as wellisolation as well Some form of receiver protectionSome form of receiver protection
What’s UnimportantWhat’s Unimportant
Ground/Ground rod qualityGround/Ground rod quality Loop shapeLoop shape RadialsRadials
Not needed in GeorgiaNot needed in Georgia Can ruin antenna patternCan ruin antenna pattern
Variable Termination ResistanceVariable Termination Resistance Vactrols have multiple problems Vactrols have multiple problems Helps F/B, nil effect on RDFHelps F/B, nil effect on RDF
Impedance ratio = turns ratio squared
Typical Impedance Matching TransformerBinocular – 77 material
Winding the matching Winding the matching transformertransformer
Primary: 4 Turns – Goes On SecondSecondary: 12 Turns – Goes on First - Matches 50 ohms (10 turns for 75 ohms)
Transformer Transformer MeasurementsMeasurements
Flat from 1.7 to 30 MHzFlat from 1.7 to 30 MHzTest R=470 ohms
Tips & TricksTips & Tricks Outdoor unit needs a drain holeOutdoor unit needs a drain hole Isolate the signal return ground (coax Isolate the signal return ground (coax
shield)shield) Buried transmission line may helpBuried transmission line may help
MUST have bury-rated coaxMUST have bury-rated coax Solder ground wire to ground rod with a Solder ground wire to ground rod with a
torch before installationtorch before installation Test matching XFMR before use (home-Test matching XFMR before use (home-
brew)brew) Run the common mode and TX Run the common mode and TX
interaction tests (home-brew or ALY-4R)interaction tests (home-brew or ALY-4R)
Okay its up – Now What?Okay its up – Now What?
Testing!Testing! Listen to AM BC Band in daytimeListen to AM BC Band in daytime
F/B should be terrificF/B should be terrific Listen on 160 and 80 – A LOT!Listen on 160 and 80 – A LOT!
Should be able to null signals and QRNShould be able to null signals and QRN
Common Mode Test – Next SlideCommon Mode Test – Next Slide TX Antenna Interference Test – TX Antenna Interference Test –
Next SlideNext Slide
Key Test # 1 - Common Key Test # 1 - Common ModeModeTest for signal & noise incursionTest for signal & noise incursion
Disconnect loop wires, find strongest Disconnect loop wires, find strongest BC band signal and measureBC band signal and measure
Connect antenna wires and measure Connect antenna wires and measure delta signaldelta signal
N4GG’s measures 40 dBN4GG’s measures 40 dB Home Brew, Isolated Grounds, BeadsHome Brew, Isolated Grounds, Beads
K1ZZI’s measures ~40 dBK1ZZI’s measures ~40 dB AYL-4R, Isolated Grounds, No BeadsAYL-4R, Isolated Grounds, No Beads
K4DLI’s measured ~15 dB until connecting K4DLI’s measured ~15 dB until connecting relay ground to antenna ground, then > 40 relay ground to antenna ground, then > 40 dBdB
Some Grounding experiments may be necessary for optimization
Key Test #2 – TX Antenna Key Test #2 – TX Antenna DetuningDetuning Find a test signal on 160 meters Find a test signal on 160 meters
and carefully measureand carefully measure Connect 160 TX antenna to an Connect 160 TX antenna to an
antenna tunerantenna tuner Run tuner through all possible Run tuner through all possible
settingsetting TX antenna should not affect F/BTX antenna should not affect F/B
Make or Buy?Make or Buy?
AYL-4RAYL-4R $259$259 May require ground May require ground
mods, ferrite beads mods, ferrite beads and rewiring for best and rewiring for best performanceperformance
Includes Preamp and Includes Preamp and BPFBPF Sometimes usefulSometimes useful Sometimes in the waySometimes in the way
Preamp BP: 1.5 – 4 MHzPreamp BP: 1.5 – 4 MHz
Looks Nice – Saves Looks Nice – Saves TimeTime
Home BrewHome Brew Parts ~ $50Parts ~ $50 DXE Preamp $109DXE Preamp $109 ICE Limiter $39ICE Limiter $39 No ground issuesNo ground issues Satisfaction with a Satisfaction with a
job well-donejob well-done Operating Operating
FlexibilityFlexibility 300 KHz – 30 MHz300 KHz – 30 MHz
Summary – K9AY Rx Summary – K9AY Rx AntennaAntennaGood performance in a small space Good performance in a small space
for low costfor low cost
Broadband: 300 KHz to 30 MHzBroadband: 300 KHz to 30 MHz
Optimum for 160M and 80MOptimum for 160M and 80M
Easy to Build, Erect, OperateEasy to Build, Erect, Operate
- Try one! - - Try one! -
Additional MaterialAdditional Material
Performance vs. Performance vs. Termination R Termination R
@ 1.825 MHz AND @ @ 1.825 MHz AND @ Rg=100ΩRg=100Ω RR (Ω) (Ω) RDFRDF (dB) (dB) F/BF/B (dB) (dB)
340 7.65 17 @ 45° 368 7.66 20 @ 48° 397 7.65 22 @ 50° 434 7.64 27 @ 52° 476 7.61 39 @ 54° 530 7.55 31 @ 57°
594 7.47 23 @ 59°
~ +/- 1%
Elevation Pattern vs. R, Elevation Pattern vs. R, Rg=0Rg=0
Which is better ???????
RDF=7.41
RDF=7.51
Elevation Pattern vs. RElevation Pattern vs. RTermTerm, , Rg=0Rg=0
Two 100 ft radials one inch above the ground that are in-line with a loop willdestroy its performance
Nearby resonant structures will degrade performanceCan be cured through detuning those objects
Termination “R” in the Termination “R” in the AYL-4RAYL-4RResistor(s)Resistor(s) R in OhmsR in Ohms680 only 6804700 װ 680 5942400 װ 680 5302400 װ 4700 װ 680 4761200 װ 680 4341200 װ 4700 װ 680 3971200 װ 2400 װ 680 368All 340