I needed an FRS radio, there is a difference between a marine radio and a normal 2-way Programmable radio?
I bought a computer VFH Marine Midland Radio hand and wondered if this is Wile line channels with FRS radios hanfheld normal channels (1 to 1 s for 2, etc.).
A marine radio is for use water * only * (yes, you may get in trouble for trying to use for the land to the contacts of the earth). This is VHF (30 MHz to 300 MHz) and will not communicate with FRS units, which are UHF (300 MHz to 3GH). Most handheld units if FRS, VHF or UHF (no matter whether they are units of ham or FRS) is generally not be usable for more than 3 to 5 miles between handhelds on flat terrain. This is due to the curvature of the earth and that there is no formula that can give a very good "guestimate" as to its scope. This formula is to take the height (in feet) of antennas and double that number. For handhelds, 5 or 6 feet okay. Now take that number and double it. We will use 5.5 feet doubled, which is 11. The square root of that number is the distance in miles to its radio horizon. The square root of 11 is between 3 and 4 (about 3). As long as the radio horizon crosses the horizon of another station, radio can communicate. In this case, another computer handheld radio would have a horizon of 3 to 4 miles. You may be able to communicate with other handheld 6 miles. Get a higher antenna (standing on top of a hill, for example) will improve the situation considerably. Although my hand antenna is only 5 or 6 feet above the ground, repeaters often I communicate with hundreds feet of the ground. If a repeater is located on a hill and has a tower that puts the antenna 200 feet above average terrain, the doubling yields of 200 and 400 square root of 400 is 20. 20 miles repeater horizon indicate my 6 miles I can use the repeater about 26 miles away. When I was in atop 23-story building that could communicate with repeaters over 100 miles away. The building was in an area of 600 feet above local terrain, more than 23 stories up with the other repeaters. I spoke with other handheld over 100 miles away. CB 27 MHz is different in the F layer (or sporadic The layer E) spread may come into play. Then openings can occur over thousands of kilometers (though not legal in the U.S.). For what it's worth, the power is not as important as some think. Is the antenna (VHF and up) in elevation. 2 fans managed to communicate through Moonbounce (bouncing signals the moon) with less than 100 watts. The moon is a quarter of a million miles away and the signal has to complete the round trip of half a million miles. 85 watts. Go figure. MURS can be considered an offer on VHF, which is license free and offers very little interference (as opposed to 27 MHz CB). You could get your 6 miles between handhelds or perhaps 20 miles between a mobile and a base unit. For longer distances on a constant basis, on its only legal alternative would be a license amateur radio (not more !!!). Morse code I've included a URL. You can do a search on Yahoo groups to find a number of radio groups fans, some dedicated to helping SWL, CBERS, and others to obtain their first license, and others in improving their license. For me, six batteries Double A has been enough (with the help of a relay) for a nice chat (every path of RF, no internet involved) with Australia. In FM. Hope this helps;) Best regards, Jim
VHF Marine Radio – DSC Radio USCG- Pt. 3
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Uniden MHS75 VHF Waterproof Two-Way Marine Radio $99.99 - Uniden two-way VHF marine radio- Dual triple and quad watch plus- JIS8/IPX8 submersible- Rapid clip-on DC charger- Large orange backlit LCD- Up to 12 hour battery life- All marine VHF channels- All NOAA weather channels- Memory channel scan- USA/international and Canadian channels- 1/2.5/5 watt switchable- Weather alert- backlit keypad- Flexible rubber antenna- Compact size- Covered by Uniden’s … |
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