Putting up an antenna on your roof can greatly increase your signal strength for both receiving and transmitting plus give more constant results than trying to find that magic spot in your house or yard with your walkie talkie. The height reduces the number of buildings, trees, cars, people, etc., that your signal has to go through to get to the repeater and vice-versa, and may even be line of sight to the repeater. So what do you need to put an antenna on your roof?
Antenna - The Jetstream JTB6 is a rugged antenna that covers the 144-148 VHF and 440-450 MHz UHF Ham bands with 3 dB gain (doubles the power) on VHF and 5.5 dB on UHF. This more than makes up for coax cable loss. It gets it's gain by concentrating the vertical omni directional radiation pattern on the horizon rather than up high in the sky. Mounted in a fiberglass tube, the length is 4' 7" and can take up to 90 mph winds. There are others that are longer and have more gain but higher shipping cost. If you want to also transmit on the 223 MHz band with the Baofeng UV-5R3 or Btech UV-25X4, then get the Comet Tri-band antenna.
Jetstream JTB6 146/446 MHz, $39.95 + $18.14 shipped from R&L Electronics.
Jetstream JTB3B 146/446 MHz, 6ft long, 126.96.36.199 dB gain, $44.95 + shipping.
Comet CX333 Tri-band 146/222/445 MHz, 10' 4" 6.5,7.8/9.0 dB gain, $168.89+
Antenna Mounting Bracket - The bracket clamps to the bottom of the antenna and bolts just below the peak of the roof with supplied wood screws. Use a drill bit to make a pilot hole to minimize splitting the wood with the mounting screws. Place the bracket level and as high up as possible on the peak, then mark and drill the holes. Fasten the bracket and check for level as the antenna needs to be perpendicular to the ground for best omni directional radiation pattern on the horizon. One bracket is fine for this size of antenna, but you can put the second one directly below the first for added wind strength. Run the coax cable up through the antenna mounting sleeve and then connect the coax cable to the antenna. Water inside the coax can ruin it so put two wraps of electrical tape around the connector at the antenna starting on the coax, up the cable connector to the base of the antenna jack and back down again. Slide the sleeve up and fasten with the bolt. Mount the antenna to the bracket. Make a drip loop by bringing the coax back up and under the eves so as not to conduct water down to the wall entry. The cable can be routed under the eves and down next to windows for least visual exposure.
Home Depot $14.06 or Amazon $13.92
Coax Cable - CNT-400 or LMR-400 are special low loss 50 Ohm cable that is almost 1/2" in diameter and connects the antenna on the roof to your radio inside the house. At VHF and especially at UHF frequencies you can lose almost half your RF power per 100 ft with this coax cable. So measure the distance with a string then select the next longer 25 ft incremental length. Ideally to minimize cable loss, the coax is cut to the exact length and connectors are then put on, but that involves soldering and proper assembly. The ready made coax source is Cable Xperts using Andrews Cinta CNT-400 low loss coax.
CNT-400 Coax w/PL259 UHF Male connector both ends, scroll down to CNT-400 to order:
25 ft 400C25 $29.95, 50 ft 400C50 $50.95, 75ft 400C75 $$75.95, 100 ft 400C100 $105.95.
Getting the Coax into the house - Yes, the best way is just to bite the bullet and drill/cut a hole in the wall vs. trying to find a vent under the eves and then go up in the attic to drill a hole in the ceiling above the ham operating position. It is really not that hard. Go to Home Depot and get a 3/8 masonary drill bit and a drywall saw. Find a spot between the studs with a stud finder or take a guess by the old tap method. Make sure no wall sockets are on the inside wall within the width between the two studs. After marking the outline on the outside wall, (inside of the mounting bracket) drill out an upper corner just inside the line all the way through to the inside wall. Cut just outside the line with the drywall saw. Mark and cut the inside wall hole. If you are in to tools, you can also use an Oscillating-Multi-Tool. If you click on the link below for the wall fixture and scroll down, you will find the info and steps to take for the installation, however, the wall fixture opening points outward and down as shown in the photo above, not inward, and put some sealant under the top and sides.
Coax Thru-the-wall Fixture from Amazon $10.79 for a package of 2.
Coil up the excess coax in the house. Once you are satisfied with the placement of your radio, secured the routing of the coax outside the house and checked the operation on the air, shoot a little Spray Foam into the wall fixture on both sides to keep moisture and the creepie crawlies out.
Base Radio - Most base station transceivers are dual band with 25 - 50 Watts out on 146 MHz and 20 - 40 Watts on 446 MHz. The least expensive is to use FM transceivers designed for mobile applications joined with a 13.8 Vdc power supply.
This way, if you are going on driving trip or event with your car, you can unplug it from the 13.8 Vdc base station power supply and plug it into the car DC power. But first, you may want to try out your new roof top antenna connected to your walkie Talkie.
Walkie Talkie - The Baofeng UV-5R antenna has a SMA Female connector. Unscrew the antenna and either screw in a SMA Female to UHF Female adaptor into the radio, or a short flexible adaptor cable to take a lot of mechanical force off the small connector from the large antenna coax. Dress and fasten the coax so that the walkie talkie does not move out of the charger. The charger can be velcro'd to the desk or shelf. To make operating easier, a speaker mic can be plugged in.
SMAf to UHFf adaptor Jetstream JT1040, $2.95 from R&L Electronics.
SMAf to UHFf 3 ft cable Jetstream 4010J3, $12.95.
Speaker/Mic Baofeng SM01, $6.95.
Mobile Transceiver - The Btech UV-25X4 tri-band mobile makes a small - 3.85 (w) x 1.38 (h) x 4.65 (d) in - base station transciever. Output power is 25 Watts on 146 MHz and 20 Watts on the 446 and 223 MHz bands. If you want to transmit in the 223 MHz band, you will need a tri-band antenna, or just stick with 146 and 446 MHz with a dual band antenna. In place of being powered by the car electrical system, a 13.8 Vdc power supply is used. The power supply listed below is ample for the 7 Amps maximum current draw, and it has terminals for charging a back up battery in case of AC power failure. Review - Notes.
Btech UV-25X4 Transceiver $129.89
Jetstream JTPS-14BCM 12A cont. DC power supply, $74.95.
The Btech UV-25X4 has 200 programmable memory channels which can easily be loaded from your computer - see YouTube Video - using the free CHIRP program, or I can do it for you. I usually load the same 127 channels as our walkie talkies to make it easier to use. Your call letters can also be programmed to show at the bottom of the screen. The 4 lines in the display can be programmed independantly. We chose to link 1 to 2 and 3 to 4. This way you can display the name of the repeater and it's frequency. As shown right, the Mt. Wilson Open repeater on 449.700 MHz is on channel 006 and the repeater we use at AC100 for the Chantry to the Finish segment, located on the top of the Telephone company building (Telco) in Pasadena, on 145.180 MHz is on channel 045. You can change channels by rotating the knob on the right or the key pad on the microphone.
There are many mobile transceivers on the market to choose from. If you want more power, the next step is in the 50 Watt 146 MHz and 30-40 Watt 446 MHz band range. The 50 Watt class of transceivers may require a larger 13.8 Vdc 20-30A surge power supply capable of more than 12 Amps continuous output.
Btech UV-50X2, similar features as UV-25X4 but dual band 50 Watts, size 5.7 (w) x 1.85 (h) x 7.5 (d) in,
200 memory channels, Review, $209.89
TYT TH-7800 50 Watts on 146 and 35 Watts on 440 MHz bands, Independant left/right volume
controls, 800 Memory channels, $199.95, with power supply $229.95
TYT TH-9800 Quad band 29/50/146 50 Watts and 40 Watts on 440 MHz, Independent left/right,
volume controls, receives Aircraft band, can do crossband repeat, 809 memories,
requires different antenna to operate on the 29 and 50 MHz bands, $214.95
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