I've lately been getting serious about GMRS and radios in general (this summer when my kids are out of school and I have a bit more time I plan to study for and take my HAM technician license test). I know the path I am headed down which is nickel and diming my way to a good setup, spending a lot more money than if I'd just "done it right" when I started. Been down that path with other hobbies. At the same time, it is often an enjoyable path and I learn a lot more than just "doing it right" to start with. I just mean, getting really nice equipment at first. I like to do things properly as I go (installation, licensure, safety, etc.)
Should I ground the coax feed for the antenna? It would be easy to do in my attic as I have a 10ga ground wire from a jetted tub I removed from my master bath when I renovated the bathroom last year. And I am installing the antenna within a few feet of where the wire runs. I removed the ground wire up to the point of the attic, but I didn't bother pulling the 100ft of ground wire all the way back to my panel. As it is an attic antenna, I am not worried about lightning strike protection. And static build up shouldn't be any real concern. Since the ground point would be all the way back to my electrical panel ground bus bar and then to earth, would that help reduce any possible extraneous RFI? Or is that likely to add RFI? A lot of the stuff I read about RFI is informative, but I can't help wondering how widely applicable it is. RFI at 10 meters is very different than RFI at 462/467Mhz. Is RFI much of a concern at the shorter wavelengths? And if so, would this ground path be likely to help? Hurt? Neutral? Everything I've read has said to keep the grounding as close as possible for a short and wide ground strap for the coax. But at times I see it mentioned, seem to be people who are working with HF installations where the ground path can be meaningfully shorter than the wavelength. There isn't a chance in fluffy bunny hades I can have a shorter than 70cm ground path, or even a shorter than 2m ground path if/when I take up HAM. I've seen conflicting diagrams of grounding the antenna coax at the radio and then directly to a ground rod (which is bonded back to the service ground). Other diagrams I've seen have the antenna coax grounded at the antenna and running down to a ground rod that the lightning arrestor is also grounded to, but are often NEC diagrams for outdoor antenna installs. And lastly I've seen diagrams where the coax is grounded both at the antenna and at the radio.
Advice would be greatly appreciated. Another question would be, should the radio chassis be grounded? It is going to be powered off portable 85wh power bank that has a 12v/10a cigarette outlet and then the pack will be recharged using a 30w PD charger. None of those has a ground and the radio (DB-25g) as near as I can tell doesn't have a chassis ground on it anywhere. Though grounding off the SO259 connector should accomplish the same thing I would think, however if the coax is grounded by the antenna, that would also be a ground path (though much longer).
Separately for an outdoor antenna, as I might go down that route at some point if the attic antenna doesn't work out. That seems much simpler. Direct ground on the mast to a ground rod, bond the ground rod back to my service panel, ground the coax also to the ground rod directly as close to the antenna as possible. Can that grounding on the coax be a lightning arrestor? Or does it need the coax grounded to the ground rod AND a lightning arrestor installed and grounded (so three connections to the ground rod, mast, lightning arrestor and coax. Or just two, mast and lightning arrestor)? If I were to install a second antenna, does that antenna need its own set of grounds to a different ground rod? can it run to the same ground rod? Can the grounding points for both antennas/coax and combined and then run down to the ground road as one wire to save having a ton of wires all running down?
The 2 antenna question is in part because of where I am located I am mostly trying to hit my brother-in-law's house 4 miles away, over a ridge as well as a local GMRS repeater over that same ridge, but about 20 miles away (and I think it is at higher elevation than my brother-in-law, probably not by much though even accounting for the repeater being on a tower). The ridge is about a 100ft rise over 1.5 miles and then 2.5miles and 100ft down to my brother-in-law's house. I haven't tested yet to see if anything is workable between us (he does not have a GMRS license or radio yet, but is considering both). The repeater I can pickup in some spots indoors as well as from my roof (single story rancher) on a UV-9g with a 1/2 and 5/8 wave length antenna. Not well on Rx, but intelligible. Tx I can only hit from my roof and I suspect it is BARELY reaching, but I get an acknowledgement from the repeater when I broadcast from the roof (I haven't tried a conversation with anyone). The two locations are roughly in the same direction, but perhaps around 10-15 degrees separated. I want an omni and I am hoping it'll be sufficient. I am installing an HYS tunable 6dBi antenna in the attic. If that isn't sufficient, but I can tell it gets me close I would try a quick temporary roof/chimney install to get it a bit higher and no attenuation from the gable end wall (just 11/32" OSB, house wrap and vinyl siding. The signal might hit a 2x4. So I assume minimal attenuation at 462MHz). And/or I'd consider installing a 2nd antenna, something like a 9-11dBi Yagi as I think the points I am trying to hit are close enough together that a Yagi would get me a significant amount more gain to those points than the 6dBi omni I am otherwise installing. I'd then just use an antenna switcher. I am hoping to test from my car using another DB-25g with a UT-72 antenna from my brother-in-law's house and use one of my sons to man the radio back at my house. My other plan if that doesn't work and is setup a ladder (he has a 17' ladder) and try from the top of the ladder with my HT just to see if I can get least get Rx with the extra elevation even though my gain would be a bit lower
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lazarus1024
I've lately been getting serious about GMRS and radios in general (this summer when my kids are out of school and I have a bit more time I plan to study for and take my HAM technician license test). I know the path I am headed down which is nickel and diming my way to a good setup, spending a lot more money than if I'd just "done it right" when I started. Been down that path with other hobbies. At the same time, it is often an enjoyable path and I learn a lot more than just "doing it right" to start with. I just mean, getting really nice equipment at first. I like to do things properly as I go (installation, licensure, safety, etc.)
Should I ground the coax feed for the antenna? It would be easy to do in my attic as I have a 10ga ground wire from a jetted tub I removed from my master bath when I renovated the bathroom last year. And I am installing the antenna within a few feet of where the wire runs. I removed the ground wire up to the point of the attic, but I didn't bother pulling the 100ft of ground wire all the way back to my panel. As it is an attic antenna, I am not worried about lightning strike protection. And static build up shouldn't be any real concern. Since the ground point would be all the way back to my electrical panel ground bus bar and then to earth, would that help reduce any possible extraneous RFI? Or is that likely to add RFI? A lot of the stuff I read about RFI is informative, but I can't help wondering how widely applicable it is. RFI at 10 meters is very different than RFI at 462/467Mhz. Is RFI much of a concern at the shorter wavelengths? And if so, would this ground path be likely to help? Hurt? Neutral? Everything I've read has said to keep the grounding as close as possible for a short and wide ground strap for the coax. But at times I see it mentioned, seem to be people who are working with HF installations where the ground path can be meaningfully shorter than the wavelength. There isn't a chance in fluffy bunny hades I can have a shorter than 70cm ground path, or even a shorter than 2m ground path if/when I take up HAM. I've seen conflicting diagrams of grounding the antenna coax at the radio and then directly to a ground rod (which is bonded back to the service ground). Other diagrams I've seen have the antenna coax grounded at the antenna and running down to a ground rod that the lightning arrestor is also grounded to, but are often NEC diagrams for outdoor antenna installs. And lastly I've seen diagrams where the coax is grounded both at the antenna and at the radio.
Advice would be greatly appreciated. Another question would be, should the radio chassis be grounded? It is going to be powered off portable 85wh power bank that has a 12v/10a cigarette outlet and then the pack will be recharged using a 30w PD charger. None of those has a ground and the radio (DB-25g) as near as I can tell doesn't have a chassis ground on it anywhere. Though grounding off the SO259 connector should accomplish the same thing I would think, however if the coax is grounded by the antenna, that would also be a ground path (though much longer).
Separately for an outdoor antenna, as I might go down that route at some point if the attic antenna doesn't work out. That seems much simpler. Direct ground on the mast to a ground rod, bond the ground rod back to my service panel, ground the coax also to the ground rod directly as close to the antenna as possible. Can that grounding on the coax be a lightning arrestor? Or does it need the coax grounded to the ground rod AND a lightning arrestor installed and grounded (so three connections to the ground rod, mast, lightning arrestor and coax. Or just two, mast and lightning arrestor)? If I were to install a second antenna, does that antenna need its own set of grounds to a different ground rod? can it run to the same ground rod? Can the grounding points for both antennas/coax and combined and then run down to the ground road as one wire to save having a ton of wires all running down?
The 2 antenna question is in part because of where I am located I am mostly trying to hit my brother-in-law's house 4 miles away, over a ridge as well as a local GMRS repeater over that same ridge, but about 20 miles away (and I think it is at higher elevation than my brother-in-law, probably not by much though even accounting for the repeater being on a tower). The ridge is about a 100ft rise over 1.5 miles and then 2.5miles and 100ft down to my brother-in-law's house. I haven't tested yet to see if anything is workable between us (he does not have a GMRS license or radio yet, but is considering both). The repeater I can pickup in some spots indoors as well as from my roof (single story rancher) on a UV-9g with a 1/2 and 5/8 wave length antenna. Not well on Rx, but intelligible. Tx I can only hit from my roof and I suspect it is BARELY reaching, but I get an acknowledgement from the repeater when I broadcast from the roof (I haven't tried a conversation with anyone). The two locations are roughly in the same direction, but perhaps around 10-15 degrees separated. I want an omni and I am hoping it'll be sufficient. I am installing an HYS tunable 6dBi antenna in the attic. If that isn't sufficient, but I can tell it gets me close I would try a quick temporary roof/chimney install to get it a bit higher and no attenuation from the gable end wall (just 11/32" OSB, house wrap and vinyl siding. The signal might hit a 2x4. So I assume minimal attenuation at 462MHz). And/or I'd consider installing a 2nd antenna, something like a 9-11dBi Yagi as I think the points I am trying to hit are close enough together that a Yagi would get me a significant amount more gain to those points than the 6dBi omni I am otherwise installing. I'd then just use an antenna switcher. I am hoping to test from my car using another DB-25g with a UT-72 antenna from my brother-in-law's house and use one of my sons to man the radio back at my house. My other plan if that doesn't work and is setup a ladder (he has a 17' ladder) and try from the top of the ladder with my HT just to see if I can get least get Rx with the extra elevation even though my gain would be a bit lower
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