HF OPERATORS
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EVALUATION and APPLICATION
OF
INEXPENSIVE LIGHTNING
SURGE PROTECTORS
for Antennas and Radio Systems
by
John White
VA7JW
va7jw@shaw.ca
11 Nov 2013 Rev 2
NSARC HF Operators
1
Some Lightning Facts
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Average duration 50 microseconds
Average speed of Lightning stroke 20,000 mph
Average Temperature 30,000 degrees C
Average Length 3 km
Average Energy 300,000,000 joules
Average Power 10,000,000,000,000 watts (10 terawatts)
Average number of strokes per flash, 4
50% of the time, strike current > 10,000 amperes
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 To understand lightning more fully, read,
http://www.nsarc.ca/hf/lightning.pdf
11 Nov 2013 Rev 2
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B.C. Strike Data
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 Supplied courtesy Ian Simpson VE7IS
 Probability of strike in lower mainland is low
11 Nov 2013 Rev 2
NSARC HF Operators
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What are the Chances?
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 Even if probability is low, some locations will be more prone to
a strike than others
 VA7JW is higher up, on a hill, with towers,
and no “cone of protection” i.e. no high
trees nearby
 “Cone of protection” is a myth anyway
 Have had a near miss. Wake –up call
 Direct strike to hemlock tree ~ 500ft away
 Lower down hill than property, let alone tower
 Takes only one hit to create a disaster – that’s the Concern
11 Nov 2013 Rev 2
NSARC HF Operators
4
The Problem
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 A “copper” highway connects our outdoor antenna systems to
our indoor radios and the operator
 Conduction of high electrical energy into the household
 Very high risk of personal injury, household damage and radio
equipment if struck
 Question is – To Protection or not bother to protect ?
 Personal injury at top of concerns
 Cost of modest protection does not have to be high
11 Nov 2013 Rev 2
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5
Nearby Strikes
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 A Direct Strike is a major threat and will cause extensive damage
 Personal survival, housing and equipment still at risk
 A Nearby Strike will have much less effect but can induce
significant voltage and current causing equipment failure
 At 300m (100ft), coax run of 30m
(100 ft) may have up to 15 kV
induced
 Equipment at risk
11 Nov 2013 Rev 2
NSARC HF Operators
6
The Plan
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Prevent Destructive Voltage and Current
from entering the shack
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 Utilize lightning arrestor devices together with an effective grounding
system to conduct lightning currents directly to earth
 Clamp surge voltages to manageable levels
 Diverge surge currents to earth ground
 Every wire – coax, rotor, control, power would have a lightning arrestor
 Arrestors must be installed OUTSIDE the dwelling such that currents
and voltages CAN NOT ENTER the dwelling
 Lightning is unpredictable – No Guarantees how well this will work …
11 Nov 2013 Rev 2
NSARC HF Operators
7
Generic Lightning
Arrestors
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1. Spark Gaps
 RF in-line coaxial
2. Gas Tubes
 RF in-line coaxial and rotor, control and power wiring
3. MOV, Metal Oxide Variable voltage resistor
 Power and Control wiring - wire to ground
 Capable of shunting large currents, kA range, for microseconds
 Clamping voltages to low non-destructive levels i.e. < 600v
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1. The Spark Gap
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 A spark gap device clamps voltage
and diverts current to earth
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 Consists of air gapped points
 Connect a spark gap device on
feed lines / wiring gapped to earth
 Excessive voltage on the line will fire the gap
 Excessive current will be shunted from line to ground
 Voltages will be clamped to manageable levels due to low arc
impedance
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Coaxial Spark Gap
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 The ubiquitous in-line coaxial spark gap lightning arrestor
Ground lug
 Commonly found on Supplier
websites (many sources on web)
 Found prices range from $2 to $20 for apparently the same
device! Typical $5
 No manufacturers were identified and no spec’s anywhere
 The price is “right” but what protection is offered?
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How Does it Work ?
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 Inserts directly in–line with coaxial cable
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 Construction of the body and center conductor retains
approximate coaxial cable characteristic impedance (50 ohm)
 The body has a ground lug for wiring to earth for the purpose of
diverting surge currents
 A screw on the body is gapped to the center conductor forming
the protective spark gap
 High voltages will fire the gap diverting high currents to the
body ground while maintaining a low clamping voltage
 Time to Investigate
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11
Introducing the “A28”
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 Supplier part numbers typically, but not always, have the A28
designation in their part numbers
 Workman Electronic Products occurs frequently in the product
descriptions as well
 No reply to my enquires to
Workman, or others, as to
performance or specifications
or country of origin
 Does one want to use an unrated lightning arrestor as part of
the surge protection plan ?
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Time to Investigate
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 How is the spark gap arranged?
 Factory set or adjustable, and how?
 What is the breakdown / firing voltage characteristic?
 What is SWR with frequency 1- 30 MHz or beyond?
 What is Insertion Loss ?
11 Nov 2013 Rev 2
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Buy Some for Evaluation
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 There are 3 variations of the same device!
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 “Type” designations are authors nomenclature, not suppliers
 Type 0 – body ground screw only, no adjustable spark gap screw
 Type 1 – body ground screw & 1 adjustable spark gap screw
 Type 2 – body ground screw & 2 adjustable spark gap screws
 Type 2 no longer available
 on-hand by author
 probably 20 years old
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Type 0 from HamCQ, $5
Type 1 from FTL Distributing, $5, p/n A28
Type 2 not available
Type 0
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NSARC HF Operators
Type 1
Type 2
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Need to Look Inside
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 Opened up side of the body to expose interior construction
 Type 0 has NO spark gap mechanism
 Type 1 has 1 adjustable spark gap
 Type 2 has 2 adjustable spark gaps
Spark Gap Screws
Type 0
11 Nov 2013 Rev 2
Type 1
NSARC HF Operators
Type 2
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Type 0 – No Spark Gap
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 No spark gap. Assume spacing from center conductor to body
IS the gap and adjusted to protect coax center conductor
 Gap on female end of connector is 1.9 mm whereas there is a 3
mm gap between center conductor and body ? ? ?
 Guess which one flashes over first?
 Flashover is calculated to be ~ 3 kV/mm for 3 x 1.9 = 5.7 kV
1.9 mm gap
11 Nov 2013 Rev 2
3 mm chamber gap
NSARC HF Operators
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Type 1 – 1 Spark Gap
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 There is an adjustable spark gap. End of screw is FLAT – should be
pointed to enhance initiation of flashover.
 Factory set gap tight against the external nut is ~ 1.25 mm
 Flashover voltage estimated at 3.75 kV
 The gap on female end is 2 mm, same as chamber
 The center conductor leaves a lot to be desired as the two piece
construction is bent and the adjustable gap is compromised
2 mm gap
11 Nov 2013 Rev 2
2 mm chamber gap
NSARC HF Operators
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Type 2 – 2 Spark Gaps
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 Two adjustable gaps using screws with pointed ends
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 Center conductor is one piece with a stepped diameter
 The step is coincident with the two gap screws
 Two sharp edges (screw and step) concentrate electric field and
enhance & define the flashover position
 The factory screw settings are unknown but when screwed down tight,
just touch the center conductor.
2 gaps
11 Nov 2013 Rev 2
Stepped chamber gap
NSARC HF Operators
2.25 mm gap
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Lightning Generator
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 Can’t generate kA of current but can generate sufficient HV to
fire protectors, observe flashover and measure voltages
 Use an old spark coil - charge it up and then discharge it into
lightning protector. Repeat about 3 times per second
 Use a Variac on input to adjust applied voltage to set output
HV*
* HV means High Voltage
115 VAC
115 VAC
Variac
Variable AC
Input voltage
12VDC
Power Supply
for coil
primary,
variable
~ 16 VDC / 0.3 A
Wall Transformer
to power pulsing
circuit
PULSED
High Voltage
Spark Generator
Hi Voltage Wiring
Arrestor
Under
Test
(AUT)
R1
10 Megohm
R2
10 kohm
Z in
10 Meg /15 pF
10 x
Probe
Tektronix 465
Scope
Copper PCB Ground Plane
11 Nov 2013 Rev 2
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Test Jig
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 Test jig made up on a copper clad PWB
 SO-239 soldered to board to hold the A28 arrestor
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 center pin and insulator removed
 HV lead from generator plugs into A28 F connector end
 10 meg* - 10k resistor 1000:1 voltage divider chain divides down
the applied HV to a level safe for the ‘scope to observe the
waveform, i.e. 1 kV in > 1 volt out
* quantity 10, 1 meg resistors
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Test Setup
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Pulsing Circuit driving
relay on coil primary
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12VDC Power
Supply for coil
‘Scope
Automotive
Spark Coil
Variac to adjust
115VAC input voltage
which adjusts 12VDC
to spark coil, which sets
the HV output levels
Test Jig
11 Nov 2013 Rev 2
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Type 0 Performance
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 As expected, flashover observed on connector 1 .9 mm spacing
 Firings in chamber are rare due to 3 mm spacing
 Connector flashover is due in part to the sharp edges on female
connector. Poorly formed.
11 Nov 2013 Rev 2
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22
Type 1 Performance
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 Gap set to 1.25 mm. Some firing seen in chamber
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 Flashover occurs on connector at 2 mm spacing
 Again, the connector flashover seems due to sharp edges on
female connector
11 Nov 2013 Rev 2
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Type 2 Performance
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 Gap set to 1 mm.
 Firings observed in chamber.
 One gap will fire before the other as the gaps are not precisely
equal
 Female connector receptacle is better formed
 Performs as one would expect!
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Waveform Measurements
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 Tektronix 465 ‘scope used to capture voltage waveform across
the device under test as devices were pulsed with HV
 Waveforms captured by tedious experimentation with camera
settings, lighting and scope trigger points (no storage scope!)
 Object was to determine
 1. at what voltage does firing or flashover initiate
 2. how quickly does it initiate
 3. what is the clamping voltage when the gap fires
 All Types 0, 1, & 2 exhibited the same characteristic waveforms
11 Nov 2013 Rev 2
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Pre-Flashover Waveform
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 Variac adjusted to apply just less than firing voltage, ~ 6 kV
 Ringing is observed as spark coil has not “dumped” its stored
energy and so that energy is dissipated coil primary circuits
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Flashover Waveform
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Variac voltage raised until firing or flashover occurs
Gap fires virtually instantly; estimated arc voltage ~ 200 V
Arc lasts for ~ 140 usec until coil energy is dissipated.
Ringing observed as residual energy dissipates after gap
quenches.
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Expanded Waveform
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 Expanded view of flashover ignition
 Shows instantaneous rise time
 ~ 1 usec settling time to gap voltage drop
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A28 Observations
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 Spark gap fires << 1 usec. Very fast protection
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 Gap voltage is estimated to clamp to ~ 200V in 1 usec
 As a first line of defense, the air spark gap method may well
divert significant energy, quickly
 No indication of the amount of current that can be sustained
and for how long
 Suppressor can divert large currents on the braid if mounted at
tower base ground level. Gap will divert center conductor
currents to ground as well.
11 Nov 2013 Rev 2
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Which to Use?
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 Type 0 - no adjustable gap.
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 provided body is well grounded, it will divert surge currents
 flashover occurs on connector – do we care? – it clamps.
 Type 1 – one adjustable gap
 provided body is well grounded, it will divert surge currents
 gap can be adjusted to flashover before connector end
 Gap adjustment procedure next slide
 Type 2 – two adjustable gaps
Dx Engineering product
 no longer available but best designed / made
 would use this if one could find a vendor
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Adjusting the Gap
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Procedure
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note – breakdown voltage for air, 3 kV / mm
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Discard the supplied gap screw. Save the nut or supply a new Stainless nut
Use a 4 x 10 mm metric machine stainless screw to replace the supplied screw
File, or grind with a Dremel © tool, a 4 sided point, 45 degree angle is good
Thread the nut on the screw up to the head, just snug
Thread this assembly into the vacated screw gap hole
Connect an ohmmeter between the center conductor and the casing
Screw the screw in until it shorts to the internal center conductor
The “thread rate” on the 10 mm screw is about 0.7 mm per turn (1 revolution)
Back off the screw min 1 to ~ 1-1/2 turns. This provides ~0.7 to 1.5 mm gap
Would not recommend less as ambient thermal change may compromise gap
Lock the screw down by tightening the nut against the case. Careful not to
disturb the setting
Use non-permanent LOCTITE © on the joint to weather seal and hold the gap
11 Nov 2013 Rev 2
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2. The Gas Tube
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 Controlled Spark Gap device
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 Two electrodes at each end
of a sealed chamber
 Chamber is filled with a gas
 Unlike the A28 Spark Gap, which utilizes uncontrolled ambient
air, the strike voltage is carefully controlled and breakdown
voltage can be specified as well as maximum currents
 Typically used across coaxial RF lines. Often used to clamp
power & control wiring as well
11 Nov 2013 Rev 2
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Gas Tube Characteristics
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 Gas tubes are tested against “standard” lightning specs
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 For coaxial cable lightning surge suppression
Example for a Typical Strike
Rise Time t1 ~ 8 seconds
Crest ~ 25 kA
Fall time t2 ~ 50 seconds
to half of crest value
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Coaxial Gas Tube
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 A Spark Gap device embedded in a coaxial housing which can
be inserted in-line like the A28 device
 Many to choose from
 (similar ratings 1 kW / to > 1 GHz)
MFJ-272
$30
Alpha Delta
$70
L-Com
$15
Poly Phasor
$65
Jet Stream
$55
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Typical Features
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 In-Line with ground lug or ground panel mounting body
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 Connector options
 typically PL style, male and female combinations
 N style male and female options, not all suppliers
 Performance
 Frequency 1 MHz to 1 GHz or greater, SWR < 1.5:1
 Insertion losses typically 0.1 dB
 Power rating, anywhere from 400 W to > kW
 Gas Tube
 Typically replaceable. Optional voltages available depending on
transmit power handling requirements
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Authors Selection
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L-Com Product AL-UFUFB-6
Excellent, detailed specifications
DC – 3GHz / SWR < 1.3:1
Insertion Loss < 0.4 dB to 3 GHz
Excellent variety of connectors (both PL and N)
Supplied with 600V gas tube. Other voltages available
PL style $15 US / N style $25 Replacement gas tubes, $5 ea
Stock, Ships UPS (this is expensive, $45, if ordering low quantities)
UHF-Female to UHF-Female Bulkhead 0-3 GHz 600V Lightning Protector - AL-UFUFB-6
 For local supply, Burnaby Radio carries the Jetstream Product Line
11 Nov 2013 Rev 2
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Testing
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 How does the in-line Gas Tube arrestor perform as compared to
the spark gap arrestor?
 Use same test jigs, HV Pulse generator and ‘scope
11 Nov 2013 Rev 2
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37
Pre-Flashover Waveform
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 Removed gas tube to ensure body of device did not flash over
at connectors – as good as best A28 spark gap device
 Applied same pre-flashover voltage of ~ 6 kV
 Same ringing characteristic as previously observed
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Flashover Waveform
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600 V gas tube installed
Instantaneous clamping, no overshoot
Clamping voltage is about 10V
Ringing is minimal as energy is very quickly and completely
suppressed
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Expanded Waveform
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 Expanded view of flashover ignition
 Instantaneous rise to 600V and clamps <<< 1 usec
 Dissipates energy extremely quick & “rings down”
11 Nov 2013 Rev 2
NSARC HF Operators
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Observations
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 Superior performance to the A28 Spark Gap
 No connector flashovers
 Clamp time estimated in nanosec’s; not measureable
 Clamp voltage very low, estimated 10 V
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Comparison A28 / L-com
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 SWR
Used AIM-4170 Vector Impedance Meter
 Insertion Loss
 Clamping Characteristics
Tectronix 465 ‘scope
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Axial Leaded Gas Tube
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 Same construction and specs as used
with the coaxial gas tube arrestor
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 Selected 150V to protect low voltage
< 30 V wired cable (not coax)
 Surge rating 20 kA 8 x 20 usec, once
 Firing voltages in the 75 to 600 V range
 Digikey Part number 2027-15-BLF-ND
 100 pieces, $85
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3. The MOV
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 Metal Oxide Varistor is a voltage dependent resistor
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 Looks like a Disc Ceramic Capacitor but it is not
 At low voltages it is open circuit (megohms)
 At some specified higher voltage
the resistance falls to a low value (a few ohms or less)
 Large currents can flow and the voltage is clamped to the rated
voltage of the varistor, i.e. for example100V
 Not polarity sensitive. Can be used to clamp AC or DC circuits
 Not suitable for RF
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MOV Characteristics
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 Refer to the blue line characteristic (Zinc Oxide ZnO type)
 Graph; Sudden drop in
resistance, high rate of rise in
current as MOV clamps to ~ 300v
 Ideally suited to rotor, power and
control cables
 MOV’s available from 20 to 2000 V
 Used Panasonic 100 volt / 6.5kA
 Digikey part number P7272-ND
 100 pieces, $50
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VA7JW Protection Plan
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 Install Primary Protection at the Tower Base to directly divert as much
Energy as immediately possible to Earth
 A28 type 1 Spark Gaps on HF coax & non-critical VHF
 600 V coaxial gas tubes VHF/UHF
 Wires use 150 V gas tubes
(VSWR issues)
 Install Secondary Protection at Cable Entrance to House / Shack to
divert residual surge currents / clamp voltages even lower
 HF 600V gas tube suppressors (lower voltage tubes will fire on 1.5 kW)
 VHF/UHF 230V gas tube
 Wires use 100 V MOV devices
 All Towers, Cable Service Entrance, BC Hydro entrance bonded #6 AWG
together with multiple earthed points (ground rods)
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Ground Rise
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 Strike current = 10,000 A
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ANTENNA
 Tower system 1,000V
 Voltage across ground rod = 100 V
0.1 ohms
Feed line
& Tower
 Voltage at top of ground rod = 100,000 V
 Side flashing may occur
 Current flowing in earth develops high voltage
gradients vs distance = GROUND RISE
0.01 ohms
Rod
10 -100 ohms
Earth
 This 100 kV will diminish exponentially with
distance from the ground point
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Cow victim of earth gradient electrocution
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Ground Rise & Grounding
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• • • • - • - - • •• - • ••• • - •
 Amount of ground rise, the gradients, the distance “out” where
harmful levels may exist, which directions, these are all
unpredictable due to circumstance of soils, terrain, etc
 Voltage gradients between system components are unpredictable
 Best one can do is tie system ground to earth ground at frequent
points to try and have system levels closely tied to the ground
rise.
 Objective is to minimize potential differences between ground
rise and antenna, and radio systems, and operator
11 Nov 2013 Rev 2
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48
System Diagram
- • - • - - • - - ••
• • • • - • - - • •• - • ••• • - •
 Primary at tower bases &Secondary protection at house entry
 Bonded ground system tying all major components together





Tower bases (all 4) direct to earth
Cable service entrance
Hydro service entrance
Copper cold water pipe
Equipment ground connected
HF ANTENNAS
Rotor
Control
5 Coax’s
VHF/UHF
ANTENNAS
Power
3 Coax’s
House
Secondary
Protection
Panel
BC
Hydro
AC Safety Ground
Primary
Protection
Panel
VHF/UHF Cable Bundle
Ham
Shack
VHF/UHF TOWER
HF TOWER
2 Rotors
Primary
Protection
Panel
HF Cable Bundle
Copper Water Pipe ground
All structures are grounded together
 Frequent use of ground rods
11 Nov 2013 Rev 2
NSARC HF Operators
49
Ground Wire Sizing
- • - • - - • - - ••
• •••
-
•
- - • •• - •
•••
•
-•
 What Gauge wire is needed to carry a strike current ?
 Wire Melt, called FUSING as in blowing a fuse, is the issue

#6 copper is Canadian
Electrical Code
requirement

For 70 sec, fusing
current ~ 500 kA

For 8 x 20uS strike at
10 kA, appears as
though #6 will survive
11 Nov 2013 Rev 2
NSARC HF Operators
50
Primary Suppressor
Coax at Tower Base
- • - • - - • - - ••
-
• •••
- - • •• - •
•
•••
•
-•
Dimensional scale drawings made to ensure fit of all suppressor systems prior to fabrication.
Center
Line
10-½”
PL CONNECTORS
NOTES
rox (zinc) Anti Seize compound to mounting threads & nuts
otection device threads with NO-AL-OX through Aluminum bracket
connections, First layer Scotch 88 black tape; second layer
on Tape; third (outside) layer Scotch 88 black tape.
PL
PL
PL
PL
PL
PL
Ar
Ar
Ar
PL
PL
Bulkhead
1.1"
PL
PL
Seal to top of protection devices to keep water from
ough bracket to lower connection
cal threads coated with Penetrox (zinc) Anti-Seize
PL
N
PL
PL
N
PL
Supressor
1"
1"
2"
Ar
Note 3
2"
Spark Gap suppressors on
2” x2” aluminum angle bar
at base of VHF / UHF tower
Ar
PL
N
PL
N
PL
PL Male
1-¼”
1/4" x 5/8" Hex Bolt
Flat / Lock / Nut
9.15"
Note 3
Tray Bottom
“PL” COAXIAL BRACKET
Height of PL and N brackets will be
different from each other as
protruding ends will conflict
¼” x 2" x2" AL Angle
13.25"
2"
3"
0.6" nom
1.65
HOLE COLOR CODES
3"
1"
1.65
1"
1-¼”
0.6" nom
5/16" dia hole for ¼” U Bolt
2"
0.25"
5/8 “dia hole for coaxial feed thru’s
Center
Line
1.1"
Drill 5/16"
4 places
1.25"
Note 1 Coaxial mtg holes to be centered on bracket
Note 2 In-board U Bolt holes measured in-situ to center bracket
on tower legs. Outboard holes are then placed 1.65" from
inboard holes
4.4"
This hole
unequipped
8.8" (as measured on tower)
Drill 5/8" 4 places
Use step drill
“PL” COAXIAL CABLE BRACKET
Scale 1" = 3"
11 Nov 2013 Rev 2
22 July 2012
NSARC HF Operators
VA7JW
51
Primary Suppressor
12 Wire at Tower Base
- • - • - - • - - ••
• •••
-
- - • •• - •
•
•••
•
-•
Dimensional drawings made to ensure fit of all suppressor systems prior to fabrication. i.e
1
Scribe line on back of enclosure
1.7"
5
1.1"
20 mm
Drill 9/64"
6
5
3
4
1
Scribe line on back of enclosure
2
1.1"
7
6
Scribe line on back of enclosure
20 mm
Nut
Apply RTV to seal both
strain reliefs to enclosure
150v
2
Mounting Hole 5-5/8"
center to center
150v
150v
150v
150v
Drill next two holes 9/64" using TB as template
9
Repeat 6, 7, & 8 for second TB
4
150v
Drill 11/64" using grounding strip as template
# 8 solder lug for drain wire 2 places)
Ground bar to be centered
On CL between mounting ears
Drill 11/16" with
Step Drill, 2 places
150v
150v
8
3
Drill 11/64"
150v
150v
150v
150v
150v
Apply Coax Seal to cable both entries
150v
12
11
9
10
8
1.1"
7
Nut
Drain hole
½”
1-½”
3/4"
Drain Holes 2 places
Drill 3/16" on DOWNSIDE
Debur holes in side and out
Note 1
1-½”
2.63"
2"
Note 1. Refer to specific tower mounting orientation of NEMA enclosures AND
location of cable strain reliefs. They are custom placed per location.
#8-32 x 7/8"
Pan Head Phillips
Note 2. Ensure that wire lead from gas tube is inserted into the clamping tube of the
TB. Wire can sometimes be inserted between clamping tube and nylon housing and
will NOT be clamped at all
# 8 Internal Tooth Lock Washer
Nut
1-1/4"
2"
Nut
Clamping
tube
Apply RTV to bottom of plate to seal against
weather. Do not contaminate screw threads
Space between tube and TB housing
Wire can be inserted in any one of 4
possible corner spaces outside of the tube
INSPECT
Note 3. Inject NO-AL-OX with syringe & 18 Gauge needle in to all tubes,
screws and spaces of T.B. All metallic parts are ferric and will otherwise rust.
Tower Panel 0.125" OR
Service Entrance Panel 0.125"
#8-32 x 5/8"
Pan Head Phillips
# 8 Split ring Lock Washer
# 8 Standard Nut
# 8 hardware
Apply clear RTV to
screw head
11 Nov 2013 Rev 2
NSARC HF Operators
12 WIRE GAS TUBE ARRESTOR
2" x 5" x 5" NEMA ENCLOSURE
Scale: Full Size 1" = 1"
22 July 2012
VA7JW
52
Primary on Tower Bases
- • - • - - • - - ••
HF TOWER
• •••
-
•
A28 Spark Gap
Suppressor Bar
- - • •• - •
•••
•
-•
Gas Tube
Suppressor
Enclosures
3 places – Rotors,
& Power
A28 Spark Gap &
Gas Tube
Suppressor Bars
2 places
Gas Tube Suppressor
Enclosures
2 places – Rotor & SteppIR
VHF / UHF TOWER
11 Nov 2013 Rev 2
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Secondary Suppressor
House Entry
- • - • - - • - - ••
-
• •••
8 wire MOV
AZ Rotor
- - • •• - •
•
•
-•
VA-4
4
varistor
5
varistor
6
6 Wh
varistor
7
7 Bk
8
8 Yl
1
varistor
2
varistor
4
varistor
5 Or
5 Gn
5
varistor
6 Yl
6
varistor
7 Or
7
varistor
8 Bn
8
8 wire MOV
HF Rotor
8
5
2
7
4 Rd
6
varistor
4 Bn
4
3
3
3 Bl
1
varistor
varistor
varistor
VA-1
varistor
3 Gn
varistor
3
varistor
varistor
varistor
2 Bk
2
varistor
2 Rd
varistor
varistor
1 Wh
1
varistor
1 Bl
varistor
HF Rotor
8 wire MOV
Elevation Rotor
EL Rotor
VA-2
•••
1 2 3 4 5 6 7 8
Bl Rd Gn Bn Or Wh Bk Yl
varistor
AZ Rotor
VA-5
varistor
2
1 Bk
2 Bn
varistor
4 Or
5
5 Yl
6
6 Gn
7
varistor
varistor
varistor
9
9 Gy
10
10 Wh
12 Iv
Shield Solder Lug
4 Or
4
5 Yl
5
6 Gn
6
7
8
9 Gy
9
10 Wh
10
11 Pk
11
12 Iv
12
varistor
varistor
varistor
varistor
varistor
varistor
varistor
varistor
varistor
tube
tube
tube
0.625
0.625
0.625
0.625
0.625
gnd
gnd
gnd
gnd
gnd
GT-12
tube
0.625
0.625
0.625
gnd
gnd
GT-13
HF Vertical
GT-16
VHF -UHF
Vertical
12 wire MOV
SteppIR Control
varistor
tube
GT-4
440 MHz
gnd
GT-2
144/2400 MHz
11 Nov 2013 Rev 2
3
tube
HF Switch
GT-14
Spare
varistor
3 Rd
Shield Solder Lug
tube
tube
2
8 Vi
11 Pk
12
varistor
varistor
2 Bn
7 Bl
8 Vi
11
varistor
1
7 Bl
8
varistor
HF Roto
4
SteppIR
varistor
3 Rd
Power & Control
Power & Control
varistor
3
1 Bk
SteppIR
12 wire MOV
VHF/UHF Power
and Control
varistor
AZ Rotor
r
1
o
EL R
tor
VA-3
varistor
tube
GT-9
Discone
tube
0.625
0.625
gnd
gnd
GT-6
1200MHz
GT-10
APRS
GT-11
Marine
tube
0.625
Coax’s: HF Yagi, HF Vertical,
VHF/ UHF Vertical, 144 MHz,
440 MHz 1.2 GHz, Discone,
Marine, APRS & 2 spares
gnd
GT-8
Spare
Earth Ground
NSARC HF Operators
54
Service Entrance
Outside View
- • - • - - • - - ••
• •••
-
•
- - • •• - •
•••
•
-•
16” x 16” Electrical Panel with Door on the right, not shown
8 wire
5 Sets of Varistor Suppressors
2 sets of 12 wire (control & power)
3 sets of 8 wire (rotors)
12 wire
2 rows of Gas Tube Suppressors
Lower Voltage than Primary
11 coax altogether
11 Nov 2013 Rev 2
NSARC HF Operators
55
Service Entrance
Outside Mounted View
- • - • - - • - - ••
• •••
-
•
- - • •• - •
•••
•
-•
Cabling from
VHF/UHF Tower
Grounding
Cabling from
HF Tower
Cabling from
VHF/UHF Tower
11 Nov 2013 Rev 2
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Service Entrance
Interior View
- • - • - - • - - ••
• •••
-
- - • •• - •
•
•••
•
-•
Note: All protectors
are on OUTSIDE of
Service Entrance
Cabling to Station
11 Nov 2013 Rev 2
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Operating Results
- • - • - - • - - ••
• •••
-
•
- - • •• - •
•••
•
-•
 Good – no issues through hot summer, wet, freezing winter
 Suppressors had had no measurable affect on performance
of the coax’, 1 through 450 MHz
 VSWR’s good & stable
 No measurable affect on any of the rotor, SteppIR control or
power systems.
 Have not been hit by lightning so ultimate performance TBD
11 Nov 2013 Rev 2
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Summary
- • - • - - • - - ••
• •••
 Personal Injury – not an option
-
•
- - • •• - •
•••
•
-•
 Small installations 1 or 2 coax’ s, few wires
 install coaxial arrestors at house entry
 Buy or make a wire arrestor assembly
 Make a entrance panel at house wall and ground
 Larger installations- (VA7JW = 11 coax’s, 5 rotor / power / control lines)
 Buy & make - materials cost estimated $1000
 avg. $62 per service includes primary & secondary protection
 Labor time? - many hours to design and fabricate (but that was fun)
 Loss of equipment due to lightning > $10,000


My drawings are available (PDF’s no charge) if anyone is interested
Visit KF7P Metalworks for metal products related to lightning
11 Nov 2013 Rev 2
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More Information
- • - • - - • - - ••
• •••
-
•
- - • •• - •
•••
•
-•
 About Lightning
 http://www.nsarc.ca/hf/lightning.pdf
 Details about the surge suppressors in this presentation
 http://www.nsarc.ca/tech_archive/Articles/Notes_on_Coaxial_Suppresso
r_30sep2013.pdf
 This Slide Show
 http://www.nsarc.ca/hf/surge_prot_rev2.pdf
11 Nov 2013 Rev 2
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60
Cost – 12 Wire Cable,
Primary MOV Suppressor
- • - • - - • - - ••
• •••- •
 NEMA rated electrical Enclosure






- - • •• - •
12 wire with 12 gas tubes
Cable fittings (2)
Ground bar in center (1)
Terminal blocks (2)
Various S.S machine screw hardware
Misc., RTV, NoAlOx
•••
•
-•
$16
$10
$10
$1
$6
$5
$2
 Total ~ $50 ea + effort.
 Commercial product ~ $95 ea

Shipping, duties, brokerage, taxes etc extra
11 Nov 2013 Rev 2
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61
Cost – Coaxial Cable
Suppressors
- • - • - - • - - ••
• •••
-
•
- - • •• - •

Type 1 Coaxial Spark Gap
$5 ea

UHF-UHF Coaxial Gas Tube
$15 ea

N – N type Coaxial gas Tube
$26 ea

PL-259 Male coax connectors
$3 ea

N style 2 piece coax connector
$5.50
•••
•
-•
 Cabinet, metal plates, angles, U bolts,
screws, ground wire, clamps, …..
~ $500

Requires on-line shopping around to get best pricing

Exchange, shipping, brokerage, duties, taxes not included
11 Nov 2013 Rev 2
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62