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#32
posted to rec.boats
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VHF vs CB Antenna?
On 11/28/2018 4:20 PM, wrote:
On Wed, 28 Nov 2018 14:22:12 -0500, "Mr. Luddite" wrote: On 11/28/2018 1:50 PM, wrote: On Wed, 28 Nov 2018 17:40:39 -0000 (UTC), Bill wrote: 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 ;-) We get fog, and lots of ship traffic in SF Bay and slightly offshore. Would be nice to know what is coming. === We use both AIS and radar in situations like that. Of course they're very useful at night also. Wayne, BTW, my friends on the "Ring of Kerry" made it safely to Charleston, SC. and have set up for the winter. This is their first voyage after all the work they did on the boat and it looks like they are enjoying the adventure big time. They *did* stop at Coinjock to sample the fare and only ran aground once on the ICW on the way down. :-) === Good for them. If you've never touched bottom on the ICW, then you just haven't been at it long enough. There are some real problem areas that are only negotiable at half tide or better, other places that have missing navigation marks, and a few spots that are badly charted. We are fortunate to have a full length keel with a metal shoe on it so the props and shafts are well protected. Charleston is not nearly far enough south for a comfortable winter on a boat however. We have neighbors down the street that just brought their 58 footer down here from the Charleston area. I agree and they realize that. They waited too long to try to get something further south ... like in Florida ... but everything was booked for a boat their size and draft. They both travel throughout the USA and Europe on a regular basis so the boat is just a temporary place to stay. |
#33
posted to rec.boats
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VHF vs CB Antenna?
On Wed, 28 Nov 2018 17:40:39 -0000 (UTC), Bill
wrote: 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 ;-) We get fog, and lots of ship traffic in SF Bay and slightly offshore. Would be nice to know what is coming. That is RADAR, a little overkill on a 20' pontoon don't you think? I doubt I will see that much ship traffic in the Estero Bay anyway, unless they can run in 2-3' of water. We have been socked in with fog tho. My wife thought it was so cool. I was navigating with aerial photos, a compass and the shapes of the edges of the mangroves. We did fine. |
#34
posted to rec.boats
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VHF vs CB Antenna?
On Wed, 28 Nov 2018 13:47:45 -0500,
wrote: On Wed, 28 Nov 2018 07:17:33 -0500, "Mr. Luddite" wrote: On 11/28/2018 7:04 AM, Keyser Soze wrote: On 11/28/18 7:02 AM, 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.Â* There are two VHF bands, low-band VHF (49-108 MHz), high-band VHF (169-216 MHz).Â* 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.Â* 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.Â*Â* But the antenna issues remain the same. For max range whatever antenna he uses needs to be of the proper length.Â* At 27 MHz a full wavelength is about 103 inches.Â* 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.Â* Have not used it in years.Â* Actually I am looking at a new radio for the boat.Â* One with AIS.Â* Maybe Santa Clause. My wife has her phone. That is all we needÂ* ;-) 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 boatÂ* ;-) Back in the CB craze (late 70's)Â* Radio Shack sold a base unit that could easily be modified if you knew what you were doing.Â* 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".Â*Â* 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.Â*Â* 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.Â* I lost interest in CB after a while. Never understood the "CB culture." I don't even like to talk on the phone that much. For a while CB had two cultures, the "good buddy" road travel communications and people like me who were more interested in seeing how far you could communicate with others, similar to HAM radio and their custom of exchanging "QSL" cards by mail confirming successful contacts. Only time I was glad to have a CB radio in my vehicle was before cell phones came along. Was traveling up Rt. 95 from Long Island heading home at about one in the morning. It was raining hard and a car whizzed by me in the fast lane. Suddenly, all I saw were his headlights flashing back at me several times. As I approached him, his car was upside down on the side of the road. He had hit a large puddle of water and had hydroplaned, causing his car to hit the center guardrail and then flip several times. Got on the CB and after a few tries contacted someone who called the state police. I helped get the guy out of his car and he sat with me in mine until the police arrived. He was shaken up big time but didn't appear to have any serious injuries. === These days everyone has emergency communications via cell phone. It's much more reliable and easy to use. Ham radio is also experiencing a decline in popularity as the internet and sat phones have made it easy to communicate all over the world. --- IBM collected a lot of hams. Back in the days when I was in DC they were already migrating to digital, hooking ASR33s (teletype) to their ham gear. Some still worked 2 meter radio telephone but not that much. The guy from Ft Myers who retired in Tennessee says they have a pretty active ham group there but they are connecting up PCs. I guess ham has become just an RF modem. |
#35
posted to rec.boats
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VHF vs CB Antenna?
On 11/28/2018 6:48 PM, wrote:
On Wed, 28 Nov 2018 13:47:45 -0500, wrote: On Wed, 28 Nov 2018 07:17:33 -0500, "Mr. Luddite" wrote: On 11/28/2018 7:04 AM, Keyser Soze wrote: On 11/28/18 7:02 AM, 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.Â* There are two VHF bands, low-band VHF (49-108 MHz), high-band VHF (169-216 MHz).Â* 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.Â* 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.Â*Â* But the antenna issues remain the same. For max range whatever antenna he uses needs to be of the proper length.Â* At 27 MHz a full wavelength is about 103 inches.Â* 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.Â* Have not used it in years.Â* Actually I am looking at a new radio for the boat.Â* One with AIS.Â* Maybe Santa Clause. My wife has her phone. That is all we needÂ* ;-) 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 boatÂ* ;-) Back in the CB craze (late 70's)Â* Radio Shack sold a base unit that could easily be modified if you knew what you were doing.Â* 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".Â*Â* 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.Â*Â* 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.Â* I lost interest in CB after a while. Never understood the "CB culture." I don't even like to talk on the phone that much. For a while CB had two cultures, the "good buddy" road travel communications and people like me who were more interested in seeing how far you could communicate with others, similar to HAM radio and their custom of exchanging "QSL" cards by mail confirming successful contacts. Only time I was glad to have a CB radio in my vehicle was before cell phones came along. Was traveling up Rt. 95 from Long Island heading home at about one in the morning. It was raining hard and a car whizzed by me in the fast lane. Suddenly, all I saw were his headlights flashing back at me several times. As I approached him, his car was upside down on the side of the road. He had hit a large puddle of water and had hydroplaned, causing his car to hit the center guardrail and then flip several times. Got on the CB and after a few tries contacted someone who called the state police. I helped get the guy out of his car and he sat with me in mine until the police arrived. He was shaken up big time but didn't appear to have any serious injuries. === These days everyone has emergency communications via cell phone. It's much more reliable and easy to use. Ham radio is also experiencing a decline in popularity as the internet and sat phones have made it easy to communicate all over the world. --- IBM collected a lot of hams. Back in the days when I was in DC they were already migrating to digital, hooking ASR33s (teletype) to their ham gear. Some still worked 2 meter radio telephone but not that much. The guy from Ft Myers who retired in Tennessee says they have a pretty active ham group there but they are connecting up PCs. I guess ham has become just an RF modem. I stood MARS watches for 6 months while at Great Lakes for ET school. They grabbed me because as a former Radioman who had attended Teletype repair school they wanted to get an old send/receive teletype machine up and running to use it with the ham gear. I finally found enough parts to get it running but then had to convert it to 60 wpm to make it compatible with civilian teletypes. I did that sorta as a side job as most of my time on duty was spent relaying voice messages to service members families. |
#36
posted to rec.boats
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VHF vs CB Antenna?
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. |
#37
posted to rec.boats
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VHF vs CB Antenna?
One of my neighbors in the late 60s was an air force guy who was big
in the MARS program. He got out of the AF and went to work with Univac and gave me a bunch of MARS stuff he had accumulated. I still have most of a 2000' spool of 30 ga wire. The 10 feet at a time I use every few months has not even made a dent in it. |
#38
posted to rec.boats
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VHF vs CB Antenna?
wrote:
On Wed, 28 Nov 2018 17:40:39 -0000 (UTC), Bill wrote: 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 ;-) We get fog, and lots of ship traffic in SF Bay and slightly offshore. Would be nice to know what is coming. That is RADAR, a little overkill on a 20' pontoon don't you think? I doubt I will see that much ship traffic in the Estero Bay anyway, unless they can run in 2-3' of water. We have been socked in with fog tho. My wife thought it was so cool. I was navigating with aerial photos, a compass and the shapes of the edges of the mangroves. We did fine. I can run in a foot of water. But a 21’ boat is not really a radar platform. As to radar, I screwed up about 50 years ago, not getting a license with radar endorsement. Friend took care of the police radars, great side business. I spent 3 years fixing airborne transport radars. |
#39
posted to rec.boats
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VHF vs CB Antenna?
wrote:
One of my neighbors in the late 60s was an air force guy who was big in the MARS program. He got out of the AF and went to work with Univac and gave me a bunch of MARS stuff he had accumulated. I still have most of a 2000' spool of 30 ga wire. The 10 feet at a time I use every few months has not even made a dent in it. I dealt with the Mars station at Hamilton AFB for a couple months. Was not there a long time. Was surprised at all the cool stuff that migrated there. |
#40
posted to rec.boats
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VHF vs CB Antenna?
On Thu, 29 Nov 2018 01:02:42 -0000 (UTC), Bill
wrote: wrote: On Wed, 28 Nov 2018 17:40:39 -0000 (UTC), Bill wrote: 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 ;-) We get fog, and lots of ship traffic in SF Bay and slightly offshore. Would be nice to know what is coming. That is RADAR, a little overkill on a 20' pontoon don't you think? I doubt I will see that much ship traffic in the Estero Bay anyway, unless they can run in 2-3' of water. We have been socked in with fog tho. My wife thought it was so cool. I was navigating with aerial photos, a compass and the shapes of the edges of the mangroves. We did fine. I can run in a foot of water. But a 21’ boat is not really a radar platform. As to radar, I screwed up about 50 years ago, not getting a license with radar endorsement. Friend took care of the police radars, great side business. I spent 3 years fixing airborne transport radars. I get the idea that police RADARs are like Bic lighters. Other than calibrating them I imagine they get thrown away if they break. Electronics these days doesn't really break that much ... why I retired. |
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