40-m-compact-4-square-antenna-ea5avl-11.pdf

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40m Compact 4-Square Antenna – EA5AVL
The EA5AVL 40M Compact 4-Square Antenna was designed to provide excellent DX communications on the 40m band, utilising
readily available components and be relatively easy to construct. The antenna has been used very successfully over the 2007-
2011 period during the sun spot minimum. DX contacts have been made regularly with EK3 Armenia, 7Z1 Saudi,VK6 Perth, K1 n
Carolina, 5F6 Morroco,UB6 Starolpol,YY6 Venezuela VO1 N. Foundland , ZF2 Cayman Is, PY7 Brazil, UN7 Kazakhstan, VE3
Toronto, CM3 Havana, YC6 Indonesia, AY1 Qatar to mention just a few.
NOTES
1. The cross arms can be oriented to any compass bearing to suit personal needs.
2. The four 1/4
λ
antenna wires are cut for the 7MHz band using the formula
1/4
λ
(feet) =234/F(MHz).
For 7050 KHz this works out to be about 33' 3" feet (10.19m).
+
Total wire require for antennas & counterpoises = 665 feet ( 202m)
3. The four 1/4 wavelength RG213 coax feeds ( VF 0.66) are approx 6.7m ( 21' 11") tip to tip of the PL259
connectors.
4. Four stiff wire capacity hat spokes are fitted, each one being 0.31m (12") long.
5. A 1.22m ( 4' 0") copper earth rod at the mast base earth the relay box & capacitor box.
6. There is one anchoring point for each vertical, this could be a heavy brick or long tent peg – there is little tension in
these wires.
7. The guy ropes are tensioned to support the whole mast.
8.
No antenna matching unit required, no rotator required, immediate direction change, low wind resistance.
Les EA5AVL
Proofread by G3YEU
Graphics by G8ODE April 2011 iss 1.3
40m Compact 4-Square Antenna – EA5AVL
Model By Igor DL2KQ using GAL-ANA Beta version 0.3 Antenna Modelling Program
Proofread by G3YEU
Graphics by G8ODE April 2011 iss 1.3
40m Compact 4-Square Antenna – EA5AVL
Model By Igor DL2KQ using GAL-ANA Beta version 0.3 Antenna Modelling Program
Proofread by G3YEU
Graphics by G8ODE April 2011 iss 1.3
40m Compact 4-Square Antenna – EA5AVL
PERSPEX FEED POINT CONNECTOR PLATE
Antenna wire
approx 33.25 feet
SO 239
Connector
Wingnut used to fine tune the antenna
wire
link
wire
Perspex Sheet
Square
Wing Nut to
connect Radials
4 off Counterpoise
Radials
each 33' 3" long
H
PLAN VIEW OF ANTENNA SITE
North
Perspex feed
point connector plate
1/4 Wavelength
50 Ohm coaxes
Mast top spreader cross arms
4.88m ( 16'0")
West
Antenna
Insulator
5.19m
(17' 0")
5.19m
(17' 0")
East
South antenna wire
& coax feeder
refer to notes above
South
4 off counterpoise
radials each 33' 3" long
Proofread by G3YEU
Graphics by G8ODE April 2011 iss 1.3
40m Compact 4-Square Antenna – EA5AVL
EA5AVL Compact 4-Square 40m Antenna - CONTROL BOX CIRCUITS
Antenna 1
North
Antenna 2
East
Antenna 3
South
Antenna 4
West
REMOTE RELAY
SWITCH BOX
off
1&2 RLA
1&2 RLB
1&2 RLC
on
1&2 RLD
off
on
500PF
COIL
COIL
COIL
COIL
RLA /2
RLB/2
RLC /2
RLD /2
RG213 Coax
DC Control Cable
Select
Antenna 1
Select
Antenna 2
Select
Antenna 3
Select
Antenna 4
on
CAPACITOR
BOX
To
Txer
S1A
S1B
S2A
S2B
S3A
S3B
S4A
S4B
off
SWITCH BOX
Select North
Select East
Select South
Select West
_
+
DC 12v-13.8v
Power Supply
NOTES
1. Both contacts of all switches and relays are wired in parallel to improve reliability of operation.
2. The relays are DPDT changeover with 12v coils, the clamping diodes are 1N1004 (100v 1A) and the capacitors are 0.1 MFD disc
ceramic.
3. Coaxial cables to the antennas are earthed at the relay switch box and are 1/4 wavelength long.
4. The reflector tuning capacitor is an air-spaced variable from a domestic radio, 250+250 pF and both section are wired in parallel.
5. The negative of the power supply is connected to the coax braid connected to the antenna relay box
6 .All switches are heavy duty toggle switches. For correct operation only one antenna is selected , the other 3 act as reflectors
7. The switches and relays are all shown in the OFF or non-operated positions. For correction operation of the antenna only operate
one of the four switches to select the desired beam direction, the other three antennas Will behave like reflectors.
Proofread by G3YEU
Graphics by G8ODE April 2011 iss 1.32

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