Download 2022-01-21 Comms Telecon Agenda

TA-FL Comms Telecon 202201-21 (draft)
NVIS Comms HF 40m & SARNET Practice
Thursday, January 21, 2022 5:30 PM EST
Agenda
• 40 meter+ communications net testing across Florida
• Assess band conditions
• Pick clear frequencies
• Log sheet – evidence collection
• Discussion Topics
• SHTF protocol for amateur radio comms
• Grounding for transient protection
• Wrap Up
• New topics
• Suggestions
FL State Licensees (2022-01-06)
40 meter bidirectional coverage
established to date:
- Pinellas County (St. Petersburg area)
- Clay County (Jacksonville area)
- Leon County (Tallahassee area)
Compare to TA-FL regions coverage
SHTF COMMS Plan
• Drafting version for our use
• Ref. AmRRON/Radiofreeq plan
published in 2013
• https://radiofreeq.files.wordpress.co
m/2013/11/shtf_frequency_list_2013
e_print.png
• Will include various radio
bands/modes/resources
Grounding and Bonding Intro
• Purpose: expose the amateur radio team to grounding best practices
for protection of equipment from various types of surges
• Discussion will be a shallow drive
• Strategy: Grow your knowledge of protection methods over time, and
implement enhanced protection methods as your assets grow
Grounding Antenna Connections for Transient Suppression
Comments
• Electrical Bonding is the practice of connecting
metallic objects that may be exposed to electrical
faults or induced voltages to the grounding conductor.
• Grounding is the attachment of bonded systems to
the earth.
• Bonding is crucial to maintaining low impedance path
to ground
Example: Vendor - Georgia Copper
•Flexible Copper Grounding Straps
•https://gacopper.com/022-strap.html
•See links on website for excellent references
• Surface preparation
• Anti-oxidant
• Brazing vs mechanical clamping
• Objective: direct lightning energy to earth ground
• Lightning surge protection uses different methodology
than standard 60 Hz safety hazard protection
• Model lightning as 100 kHz high voltage pulses
• Wire, braid straps, solid straps are available for
different purposes. Solid bonding straps perform better
for lightning protection because of low impedance,
skin effect, etc.
• 1.5” copper strap is about $2/foot (100’ roll)
• 3” copper strap is about $3.75/foot (100’ roll)
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8’ ground rod every
16’
Cleaner and antioxidant applied to
mating surfaces
Stainless steel HW
Buried strap
Grounding Antenna Connections for Transient Suppression
Grounding Antenna Connections for Transient Suppression
• The next 4 slides are grounding guidance based on an ARRL
referenced article from engineer CHARLES T RAUCH, JR (W8JI)
• No interpretive liberties taken on the slides
• http://w8ji.com/house_ground_layouts.htm
• Use slides for future reference when pursuing your ultimate
protection solution
Grounding Antenna Connections for Transient Suppression 1
Poor but Commonly Used
•
The most severe and frequent damage is normally not caused by a voltage
difference between each conductor in a multiple wire cable, but from those
conductor groups or bundles to other conductor groups or bundles. Nearly all
severe lightning damage is caused by lightning currents flowing through the
house wiring as common mode current.
•
This first example has severe ground loops. It is a danger for many reasons. It
does not protect for power line neutral faults, equipment failures, or lightning.
•
With a system like this, we should plan on damage when lighting strikes
anywhere near electrical power lines or antennas.
Drawing on Left
•
This system is the most common type of wiring used by Hams and CB'ers. It
has a tower ground rod or rods, an equipment ground rod or water pipe
connection, and an entrance panel ground at the electric meter. It does
not comply with national electrical and fire codes, because it is independent
entrance grounds.
•
The dashed line from the electrical service entrance panel to the radio room
represents the power line leads in the house.
•
The heavier solid line represents all control and feed line cables from the
antennas.
•
This is a very poor setup. Lightning protection, regardless of quality entrance
protection devices that might be installed, will be almost nonexistent. Common
mode lightning currents, the worse kind, will simply loop through equipment to
the powerline. This is true if lightning strikes on or near power, CATV, or Telco
lines, or if lightning strikes on or near your antenna system.
Grounding Antenna Connections for Transient Suppression 2
Better but Not Perfect
•
This system adds a wide, heavy connection (shown as a thick black line outside
house) between the entrance grounds. This connection could go under the house. My
bonding connection, for example, goes directly under my house in the crawl space. I
use 3-4 inch wide copper flashing with no splices or bends under the house. My
bonding connection is kept away from other metallic objects like plumbing,
ductwork, and wiring, even though it routes right under the house.
•
This bonding connection significantly reduces chances of damage from power line
neutral faults and lightning strikes on the power lines or your antennas. This system
meets national fire protection suggestions. (Although it is much better than the
common isolated ground installations, lightning protection can still be improved.)
•
The nearer the radio room entrance panel and ground is to the electrical service
entrance ground, and the lower bonding conductor resistance and impedance is
compared to the impedance and distance of mains wiring to the radio in the house, the
better this system will work! (Remember lightning has considerable higher frequency
energy, treat it like RF.)
•
The dashed line from the entrance panel to the desk again represents all of the power
and telephone lines.
•
The lighter solid line represents feed line and control lines. It goes through a
grounded entrance panel.
•
The heaviest line is the bonding conductor.
•
Any desk ground wire should route parallel and near the operating desk to feed line
and control wire bundle entrance panel to the feed line entrance panel. Do NOT run
the desk ground directly to the station ground rod.
•
Remember while this is much better and meets codes, it is still not the best
configuration. A portion of common mode lightning currents will still flow through
equipment to the mains ground unless the radio equipment is unplugged or
disconnected from all cables and grounds going to the entrance panel, or both.
Grounding Antenna Connections for Transient Suppression 3
Better For Gear but Bonding Missing
• This is another system that significantly improves
protection of the equipment at the operating desk.
Unfortunately it omits the critical ground bonding
necessary for full house protection. It does NOT meet
national code requirements. The mains ground is not
bonded to the station entrance ground.
• EVERYTHING on the desk or connected to the
operating desk in the radio room has to routed from the
room common point entrance to the desk. No exceptions!
• The three lines from the panel to the desk are all of the
power lines, a line representing all of the control lines
and antenna cables, and the ground wire.
• These lines can and should be bundled or closely spaced
if possible.
• The problem? While it forms a protection zone in the
radio room, the path for common mode lightning
currents between the antennas and the power lines is
through house wiring! This can cause a large voltage
difference between electrical wires and other metallic
conductors throughout the house.
Grounding Antenna Connections for Transient Suppression 4
Best by Far
• This system meets all codes. This system is nearly as good as
bringing all antenna system cables and wiring in at the house
utility entrance (which would be perfect).
• EVERYTHING on the desk or connected to the operating desk
in the radio room has to run from the room common point
entrance. No exceptions!
• The closer the radio room cable entrance is to the power mains
entrance, the more effective this system is.
• The two lines from the radio room entrance ground panel to the
desk include all power lines, with the medium size solid line
representing a bundle of all control wires, all antenna cables and
any desk grounding wire. These lines should be bundled or
closely spaced.
• Everything entering the desk area, including Telco and power
connections, must be routed from the radio room entrance panel
common point.
• The value of the optional tower-to-station bonding conductor
connection (longer dashed line) depends on distances. If the
tower or antenna is near the house, it is better to bond it in. If
the tower if more than 50 feet away, it might as well be isolated
on its own ground because the impedance will likely be too high
to be an effective bond.
Types of Surge Arrestors/Transient Suppressors
• Gas Discharge Tube
• High voltage causes gas to
ionize, conducting the
current to ground
• Energy discharge - highest
• Response time - slow to
trigger
• Clamping voltage - 600V
threshold for RF transorb
(typ.)
Types of Surge Arrestors/Transient Suppressors
• Metal Oxide Varistor (MOV)
• Resistance is lower at high
voltages, causing current to
discharge through device to
ground
• Most common
• Many sizes, based on energy
absorption capacity
• Moderate energy discharge
• Moderate trigger speed
• Variable turn-on thresholds
• Found in residential whole house
protectors
• Optionally mount in a service
panel
• Power strips, electronics products
Types of Surge Arrestors/Transient Suppressors
• Zener Diodes
• Threshold voltage causes
avalanche of current to
discharge to ground
• Lowest energy discharge
• Fastest trigger speed
• Variable turn-on thresholds
• Electronics products
Protection of AC line power at receptacle
• Hybrid protectors have >1
type of device, including
inductor and capacitor based
filters
• Multi-stage – see schematic
• Example: Tripp Lite Isobar
Outlet Surge Protector ($70)
• MOVs, toroidal balanced
chokes, ferrite rod-core
inductors, VHF capacitors,
thermal fuse
• https://www.tripplite.com/iso
bar-8-outlet-surge-protector12-ft-cord-3840joules~ISOBAR8ULTRA
New Discussion Topics
• Any member is welcome to brief a topic of interest
• Examples
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HF dipoles in trees, masts, field locations
QRP and field operations
Working with property restrictions (HOA)
Grounding and bonding 
Beacons
Digital modes
NVIS review
EMP and Faraday cages
Portable generators
Cool tools 
Repeaters and use cases (e.g., SARNET, local club repeaters, using GPS/databases)
Programming Retevis RT devices
Handheld Transceivers and VHF/UHF use cases
CW (Morse Code)
Others?