BASE STATION SETUP Considerations and choices 1. Operating
BASE STATION SETUP Considerations and choices 1. Operating location in the house 2. Antenna considerations 3. Feed line: choices and considerations 4. Feed line & baluns 5. Feed line entry into house 6. Outside grounding, lightning/surge protection 7. Antenna recommendations 8. Antenna poles and mounts 9. Test your antenna; tune it.
Location Considerations Where in the house for your radio desk? Operating location preferably on same side of house as the antenna = shorter feed line. Operating location near a window or other feed line entrance point. Ideally near ground level for ease of grounding. Desk/table space, seating, power, lighting, heating? Free from conflicts with other household activities!
Antenna Considerations The antenna: Wire, vertical, tower-mounted? What bands will you be operating? Purchase or build it yourself? What does your pocket book & your site seem to offer or suggest for an antenna? Potential anchor points? [House, trees, chimney, poles] Obstacles or dangers? Away from electrical noise generators? Vehicular, pedestrian or animal traffic? Trees or falling limbs? Entry points for feed lines into your shack? Can you get help erecting an antenna or will you have to do it by yourself? [Answer: MARC members will help.]
Feed Lines Balanced-line (window / ladder line) or coax cable? Balanced-line: lower signal loss, less expensive than coax but concerns on durability, placement close to metallic structures and must be above ground. Will probably require a balun to transition to coax for entry into the house. Coax cable: stronger, can be run closer to metals, but more expensive, greater loss, requires careful waterproofing. Hanging / Supporting the Wire
Antenna Use high quality UV-resistant rope (Manstrant, Kevlar, etc.) Use marine-grade pulleys sized appropriately for the rope Trees are great, but if you toss a line over a V in the tree, the tree will soon grow over the line and immobilize it. Better to screw a eye-bolt into the tree, then attach a pulley to the eye-bolt and run your antenna haul line through the pulley. If practical, attach a down haul line to antenna center connector. This is a separate line from the line that runs from the connector thru the pulley. Trees move in the wind - use pulleys and weights at the ends of the
antenna lines so your antennas will move with the tree and not snap. Attaching to a Tree Balanced Lines: True Ladder Line vs. Window Line Connecting a Balanced Line to the Antenna Balun ?
Balanced-to-unbalanced (balun): transitions from a balanced-flow (antenna wire) to an unbalanced-flow in a coax feed-line. Should be done at the point where the transition takes place. For coax feed: at the antenna. For a coax-fed wire dipole, a simple 1:1 ratio choke balun up in the air at the feed point. For a ladder-line feed, a balun at the point where the change from ladder-line to coax takes place.
Some tuners have a build-in balun. Simple Air-Choke Balun Antenna A 1:1 choke balun (sometimes called an ugly balun). For 160 to 10 meter HF use: @18-21 feet of coax wound on a PVC pipe. Diameter of PVC does not Really matter as long as you can get the desired 18-21 feet of coax into a fairly compact Configuration. The choke balun will serve to prevent the coax
Itself becoming a radiating part of the antenna system. A field-expedient choke can be made by handcoiling a length of your coax into coils maybe 6-8 In diameter & using electric tape to keep them formed into a coil. Other Baluns Other baluns needed for impedance transformations can be made or purchased. Commercial baluns for 1:1, 4:1, 6:1, 9:1 impedance transformations can be found for
maybe $20-50 on-line. These are usually wound-wire on ferrite torroids, sealed against the weather, and are ready-to-go. These are probably good choices for anyone wanting to skip having to find the core, the wire, the enclosure need to make your own balun. You can make or purchase ferritebead-based 1:1 choke baluns. There are many websites describing various designs. This one is offered on eBay for $30.95.
Feed Line Entrance into House Ladder line or coax feed-in? MFJ- 4602 Feed-through Panel, $65 Red cedar, stainless steel UG-363 Bulkhead connector 6,8,10,12 long; requires 5/8 hole through wall or foundation. $10-20 depending on length.
Cable stand-offs, $8 for 4 Wall Entry Plate Roof Vent Entry 2-plate set MFJ plate on Left replaces one for each side of wall soffit vent shown on Right
Outside Grounding Heavy copper braid is preferred over solid copper wire. Runs as short as possible. Everything is clamped, not soldered or simply twist-attached. 8 ft copper or copper-clad ground rod driven into ground far enough away from your house so the rod is not in the dry or protected area beneath the roof overhang. Your antenna grounding system must be connected to your standard house grounding system so that you have a single house grounding potential.not two separate grounding systems. Use heavy #6 or #8 solid copper wire.
If you have a tower or mast-mounted antenna, you will additionally need to ground that at the tower/mast site per the manufacturers recommendations. LIGHTNING PROTECTORS Alpha-Delta brand lightning Surge protector, about $52 MFJ sells a gas-discharge Type protector for $20 Replacement gas
discharge tube $9 Antenna Choices HF: wire antenna or possibly a vertical HF antenna. Wire requires anchor points and space to set up. VERTICAL requires less ground space but likely necessitates a good commercial antenna, a crew to erect it, adequate guy wires, and very likely laying out a field of radials from the base of the antenna.. VHF/UHF: vertical polarity is usually required for voice. How far will I have to communicate? Directional or
omni-directional? Height is critical: How high can I go ? My Personal Recommendations for First Antennas HF: New Carolina style Windom: between trees, 20-30 ft high, 4:1 balun, 21 feet vertical coax radiating section, 50 ohm coax feed-line to tuner. 40 meter WL Windom = 67 feet; 80 meter WL Windom = 133 feet. OR an 80 meter full-WL horizontal quad- loop strong 20+ feet high between four poles or four trees; 2:1 balun or a WL matching section of 75 ohm coax, then 50 ohm coax feed line to tuner. 80 meter full WL version would need 272 feet of total wire.
OR a simple G5RV antenna: @102 feet flat-top, center-fed dipole with either ladder-line to a 1:1 balun, then coax to tuner OR with a 1:1 balun aloft and then 50 ohm coax into your tuner. VHF/UHF: a commercial, fiberglass-cased ground-plane vertical antenna atop a tall guyed pole, with 50 ohm coax feed-line to the radio. Commercial Dual-Band Ground-plane Antenna My base-station VHF/UHF antenna. Diamond brand X-300A dual band Fiberglass construction,
10 ft tall, max 200 watts. SWRs: 6.5 on 2m; 9.0 on 440 MHz. Cost about $160 These commercial antennas come In a variety of lengths, costs so you can select one that fits your needs & pocket book. 2014 Technician License Course
J-POLE Antenna Another possibility for a VHF or UHF antenna is to either make or buy a J-pole design antenna. There are numerous websites that show how to make J-poles. Poles 4-6 ft locking fiberglass
sections, 1 to 2.5 dia., maybe $100-200 depending on height. MFJ 33 ft, 8 x 4 ft Twist-to-lock sections, Base section 1.75 dia., $80 Military surplus camo net Support poles, fiberglass,
4 ft long, cost maybe $4-5 each You can also find steel or aluminum pole sections 4-6 ft long which fit together to Form a tall mast; all of these will require guying. Poles & Sockets Aluminum or fiberglass painter poles from Lowes, 12 ft telescoping down to 6 ft long. Truck anchor is steel
tube & welded rebar; drive truck tire over it to hold it down. Sockets assembled from steel pipe or PVC pipe and metal rods MORE BASE MOUNTS.. Steel roof-top mount
For lighter weight antennas $17 A base mount like this could be attached to a roof or perhaps ground-mounted to hold a smaller diameter pole for a VHF/ UHF type antenna. MFJ also sells a folding tripod stand with a 6section fiberglass telescoping mast that
extends to 18 feet for $160. Weighs about 15 lb. and collapses down to 6 dia. X 54 inch bundle. Questions? May The Force Be With You Obi-Wan Kenobe, 1971
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