Allflex Panel Antenna Tuning Document – July 04
Getting Started.
1.
The antenna / reader kit is comprised of a control box (metal box with ammeter, buzzer, flasher lights etc), plus the antenna (black plastic panel). The control box is
screwed to the antenna with 2 stainless steel screws and the 2 components (box and antenna) are joined by a cable that plugs into the control box.
2.
A good starting point is to assemble the
system and power it up in a free air
environment (an area away from steel,
computers, motors etc). Note. The system
is designed to run off an automotive battery
or a specific 240volt AC power supply.
You should not be testing with anything
other than these power sources. When
testing originally in free air, have all other
electrical equipment switched off totally
and not connected to the antenna.
3.
This free air reading will vary from model
to model. It is usually around 0.4 amps for
large antennas and around 1.20 amps for
medium antennas. The read distance for
cattle tags should be around 900-1100mm
and 650-800mm for sheep tags.
4.
Move the antenna to where it is to be
mounted in the race or crush. As you can
see from the picture above, the antennas can
be mounted directly onto steel pipe work if required; however, you should note that steel work does not form a frame “around” the perimeter of the antenna. Metal that
forms a continuous frame around the antenna will definitely absorb all the transmitted power and you will be unable to tune out this effect. Similarly, the antenna cannot
be mounted onto steel plate, because again, the steel plate will absorb all the energy and this cannot be tuned out. Note – even as shown, the antenna should be mounted on
plywood to protect it from the damage.
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Allflex Panel Antenna Tuning Document – July 04
5.
Note the ammeter reading when you have located the antenna in the new position. If the current has decreased, the antenna has been detuned by steel and needs retuning.
If the ammeter has only moved marginally (say 0.1 for large and 0.3 for medium), or not at all, check the read distance, it is likely that the system does not require any
tuning. In the example above, the steel certainly detunes the antenna but it can be retuned and will work very well.
Tuning
6.
If you decide that the antenna has been detuned and by positioning it in the race, or crush it will need tuning. To do this you will need to open the control box. Inside the
control box you will see the electronic circuit board that drives the antenna – at the end you can see 2 wires (the antenna wires) that join the circuit board. Below that you
will see 2 banks of small green square components. (They are the tuning caps). Beside the tuning caps you will see rows of pins. Some of the pins will have small plastic
shunts joining some of the pins. These shunts are used to join more tuning caps into the circuit. There are spare shunts taped inside the lid of the box.
7.
Before you start, use the record sheets below to record the original factory shunt
positions and current (when the antenna is in free air and mounted in the desired
location). The small sketch below represents the 2 banks of pins as well as
location of the shunts as showing the photograph.
Antenna
connection
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
8.
Record the original factory shunt positions and current drawn in free air and then when located in the race or crush.
Antenna
connection
Free Air Current?
Pins
9.
Current when in position?
Now that we have a starting point we will alter the number of tuning caps in the circuit to try and tune out any effects of
steel etc. Note - when tuning, keep the shunts balanced on each side / row. That is, if you move a shunt on the left row of
pins, position a shunt in the same position on the right row as well. Tuning is done with the power on. What you want to
see is the current peak. When you see the current peak – the antenna is tuned.
10. Given that there are 5 sets of pins, that means that there are 31 different combinations where you can place pins. It is
smart to follow a sequence when tuning so that you alter the tune incrementally rather than randomly.
11. To do this, start by removing all the pins.
12. Then step through each combination and record the current as you go. (Spare shunts are taped under the lid) – However,
we know if you want to take a short cut – experience tells us that large size antennas usually tune between combinations 0
and 6 and mediums between combination 22 and 31. If you wish to save some time you can start around these values
rather than trying every combination.
13. At the end of all combinations, review what combination gave you the peak current – reset the shunts to that combination
and test the read distance. The antenna should be tuned and provide good read distances.
14. Please use the images on the following pages to record the current for each combination.
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Allflex Panel Antenna Tuning Document – July 04
Combination 0
Combination 1
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Pins
Combination 2
Current?
Combination 3
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 4
Current?
Combination 5
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
Combination 6
Combination 7
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 8
Current?
Combination 9
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 10
Current?
Combination 11
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
Combination 12
Combination 13
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 14
Current?
Combination 15
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 16
Current?
Combination 17
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
Combination 18
Combination 19
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 20
Current?
Combination 21
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 22
Current?
Combination 23
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
Combination 24
Combination 25
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 26
Current?
Combination 27
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Combination 28
Current?
Combination 29
Antenna
connection
Antenna
connection
Shunts
Pins
Current?
Shunts
Pins
Current?
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Allflex Panel Antenna Tuning Document – July 04
Combination 30
Combination 31
Antenna
connection
Antenna
connection
Shunts
Current?
Shunts
Current?
15. What combination gave you the maximum current?
the best read distance was achieved?
What current was achieved?
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What was
Allflex Panel Antenna Tuning Document – July 04
Reader PCB Assembly
Ammeter
with 1 Ampere
fullscale range
Red
Blk
6 Volt
Battery
Panel Reader Antenna
Figure 1(a)
largest values
To Exciter
Amplifier Output
Equivalent Circuit
smallest values
Figure 1(c)
Figure 1(b)
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Antenna
Allflex Panel Antenna Tuning Document – July 04
The following table represents the jumper positions and the incremental sequence in which jumpers should be added for tuning:
Largest Capacitor
Value – 1500 pf
1000 pf
470 pf
220 pf
Smallest Capacitor
Value - 100 pf
Current Value
Measured
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Total Tuning
Capacitance
0
100
220
320
470
570
690
790
1000
1100
1220
1320
1470
1570
1690
1790
1500
1600
1720
1820
1970
2070
2190
2290
2500
2600
2720
2820
2970
3070
3190
3290
Combination
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31