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![]() On Wed, 28 Nov 2018 15:44:13 -0500, John H. wrote: On Wed, 28 Nov 2018 14:51:15 -0500, wrote: On Wed, 28 Nov 2018 07:02:16 -0500, "Mr. Luddite" wrote: On 11/27/2018 11:15 PM, wrote: On Wed, 28 Nov 2018 03:06:28 -0000 (UTC), Bill wrote: Mr. Luddite wrote: On 11/27/2018 7:36 PM, wrote: On Tue, 27 Nov 2018 17:47:44 -0500, "Mr. Luddite" wrote: On 11/27/2018 5:22 PM, wrote: I have a uniden CB radio (new) and have an existing larsen wb vhf radio already on my truck. Will this antenna work with my new radio. Derek Can't determine without knowing what freq range the truck antenna is "cut" for. There are two VHF bands, low-band VHF (49-108 MHz), high-band VHF (169-216 MHz). Marine radios operate in the high band. Generally it will receive ok but transmit range may be limited due to high standing wave ratio (SWR). Even a marine VHF antenna should be tweaked in terms of length to minimize SWR in the middle of the radio's freq range. He is talking about CB (27mz) so that is over twice the wavelength of the lowest frequency VHF. SWR is really going to be ugly but since they are capped at 5w, (usually more like 4.5) I doubt the magic smoke comes out but he won't be "getting out" far either. If his "truck" is a real one (breaker good buddy size) and he has 8-9' from mirror to mirror the best antenna is the co phasers you see on big rigs. Otherwise it is hard to beat a bottom coil loaded ~48" antenna right in the center of the roof. That is what I had on my van but you had to remember to take off the vertical when you went into a parking garage. ;-) I completely missed that it was a CB radio he was talking about. Thought he was talking about a new VHF Marine radio. But the antenna issues remain the same. For max range whatever antenna he uses needs to be of the proper length. At 27 MHz a full wavelength is about 103 inches. A half wave antenna would be about 51.5 inches long and aquarter wave length antenna would therefore be about 25.75 inches. If really anal about these things, an SWR meter should then used to trim the antenna length to the lowest SWR on channel 20 (mid-range). I have an old SWR meter from the CB craze years that I never use anymore but for some reason it's one of those things I just can't throw away. I have one for my marine VHF. Have not used it in years. Actually I am looking at a new radio for the boat. One with AIS. Maybe Santa Clause. My wife has her phone. That is all we need ;-) Worst case I call a tow pirate but I have plenty of neighbors who owe me a tow. Sinking is not an issue, we will just wade ashore, I will plot a course through the mangroves with my aerial photos and boy scout compass and we will walk home. I do have loppers on the boat ;-) Back in the CB craze (late 70's) Radio Shack sold a base unit that could easily be modified if you knew what you were doing. I bought one along and acquired a list of the required modifications. The modifications added an additional 40 channels (unauthorized) and increased the carrier power from 5 watts to 15 watts. It also increased the effective single sideband mode power to over 30 watts depending on how much you modulated it which was also another "tweak". At the time we lived in a rented house near the shore and on Sunday mornings I could communicate via "skip" with people in much of eastern Europe, as far away as Italy. In the evening I could easily talk to people west of the Mississippi using skip as far away as California, depending on the time as the sun set. Ended up doing the same mods for a couple of people who also bought the same Radio Shack radio. Don't know whatever happened to that radio. I lost interest in CB after a while. CB was pretty big down in Southern Maryland because a decent base station with an illegal antenna (too tall) could reach 15-20 miles down the bay. If you had a decent marine antenna they could hear your answer. Most of my time was talking to truckers tho. I did make some pretty good friends over the years. My longest distance conversation was with a trucker on the west side of El Paso, TX, while I was approaching from the east side on I-10. We were both on high ground with the valley between us and were over 30 miles apart. I just looked on Google Earth and they were getting out a lot farther than I thought on the Chesapeake. The base was a Schiebels on the Potomac, north of Point Lookout and we used to fish that ridge that you see on GE south of Tangier Island. Usually we were shaky getting them all the way down there but we were usually OK by the time we got to TI. We could always raise the Bay Queen, the head boat out of Schiebels. I think they may have had a foot warmer on that boat tho. The antenna was also 30' above the water. They were in constant contact with the base. Everyone used obscure references on the radio so as to not give away all of the fishing spots. ;-) I am not sure we ever fished anything except that ridge, that was not that well known ... before GE anyway. This is the first time I noticed it but I know that is where we went. |
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