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epowell
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Joined: September 23, 2015
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Location: Czech (mostly) Vancouver (sometimes)
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 Posted: Fri Nov 29, 2019 10:37 am Post subject: Re: CB Radio what setup do you have? |
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| dobryan wrote: |
| epowell wrote: |
my apologise... I didn't read this thread, but thought I'd jump in with a question.
I have a CB in my van - fully functional, but I don't see any use for it >>> I am intending soon to just rip it out and throw it in the trash - but this thread made me think perhaps I should ask first. Does my CB have any value? Is there any point to keeping it in?
I do NOT own a mobile phone, so maybe this CB could have some value in a potential emergency? |
Bingo on the emergency use.  |
maybe I should figure out how it work..... 
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nemobuscaptain
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Joined: March 07, 2002
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| Posted: Sat Nov 30, 2019 2:57 pm Post subject: Re: CB Radio what setup do you have? |
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| epowell wrote: |
| dobryan wrote: |
| epowell wrote: |
I do NOT own a mobile phone, so maybe this CB could have some value in a potential emergency? |
Bingo on the emergency use. |
maybe I should figure out how it work..... |
Wire it up, connect the antenna (make sure you have a good ground and ground plane) turn to channel 9 (emergency channel), say help. Ch 19 (trucker channel) might be used in your area too. Time of day greatly affects CB. You might get more range at night.
There are some "export CBs" or CBs marketed at 10meter Ham rigs available on Amazon and elsewehere that have more than than 4 watt transmit. However these arent actually legal in US, although the FCC doesnt seem to enforce this much at all.
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Last edited by nemobuscaptain on Sat Nov 30, 2019 3:30 pm; edited 1 time in total |
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nemobuscaptain
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| Posted: Sat Nov 30, 2019 3:08 pm Post subject: Re: CB Radio what setup do you have? |
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| kourt wrote: |
I've got a 102" whip mounted on a steel Rocky Mountain Westy bumper.
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That is a cool rig and antenna. Im sure you know that some people modify those 857s to transmit on CB freqs, despite this being technically illegal.
Your antenna is very directional from there. Obviously your antenna will be blocked to the front but also the antenna itself will detune because of that vertical piece of metal running vertically just inches from the antenna. Generally you want the antenna to be at least 45 degrees from the metal. Im sure the yaesu tuner can compensate but you are wasting much of your rf as heat in the tuner instead of radiated power. If it's a 4 watt CB inside the bus, that can be a problem.
It is secure though and I know some think that is the most important.
I suspect you'd be better off with a shorty mounted on a drip rail or on one of those hatch mounts (assuming a good ground) than that 102 mounted on a bumper.
I used to do some installing for an agency needing covert antennas. We tried to explain to them that there is no free lunch and the location of the antenna greatly affects propagation. People thought they could mount a tiny antenna on a bumper (under a plastic bumper cover) or running inside the rear window and parallel with the window edge metal and have good propagation. it isn't possible. There is no free lunch.
Here is a visualation of that though it is dealing with vhf. 27mhz would be similar though 27 mhz would need a much longer ground plane (basically as long as your 109 antenna).
Note that a -3db equals basically cutting your power in half. See that moving the antenna from the center of the roof to the bumper results in -3db. This means that a 4 watt CB would only radiate 2 watts. Im sure a bumper mount is probably another -3db worse. You would radiate 1 watt and reflect 3 watts back. The truth is you'd probably be better with a 4 watt CB walkie talkie and one of those long metal antennas at least if you can stop and get out to make the calls for help.
General rules: you always want the whole antenna above the roof, and on a good metal flat (or 45% degree at least ground plane or metal), and solid ground (many hatches and body parts are insulated).
Almost any antenna will receive. But it must be right to transmit well. With only 4 watts of power on CB, you really need a good antenna. If it isn't right, you may be reflecting 3 or 4 times the power back at the radio and either destroying it, shutting it down, or forcing it to lower it's power transmitting. Many of these bumper or spare tire mounts transmit only 1 watt or less and reflect 3 watts or more back at the transmitter.
FWIW, my theory is that you could mount on the drip rail of the westy and use the metal underneath without the fiberglass affecting it much but I've never really verified that.
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Hoover Sermons: https://www.vwsage.com/images/vwsage/Bob%20Hoovers%20Sermons.pdf
Last edited by nemobuscaptain on Sat Nov 30, 2019 4:45 pm; edited 1 time in total |
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nemobuscaptain
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| Posted: Sat Nov 30, 2019 3:47 pm Post subject: |
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| Dampcamper wrote: |
Technologically the FRS is more sophisticated, CB is old-school technology. But that shouldn't be a problem for anybody who drives a Vanagon, right?
CB runs around 29 MHz frequency and can often "bend" around terrain and travel further than FRS, which runs in the UHF band (like 465 MHz), is more line-of-sight and is in most cases much more limited in range.
FRS works great in small areas and especially (if you set your radios up with a coded squelch) for just communicating amongst "yourselves". |
GMRS is available up to 50 watts and detachable antennas (including vehicle mounted antennas). Another issue is that the UHF wavelength for FRS/GMRS is so much smaller so it is much easier to get an efficent antenna. That is to say a 1/2 wave antenna for a FRS/GMRS channel (460ish mhz) only needs to be approx 13 inches long while an antenna for a CB (29mhz) has to be 203ish inches. Coils can make those lengths shorter but at a cost of less efficient radio propagation.
Despite the band characteristics, I'd guess you are going to have a tough time competing with a 50 watt GMRS (or even a 5 or 10 watt one) with a 4 watt CB in any terrain. The truth is without a repeater the curve of the earth is going to limit you to basically 5 ish miles tops anyway.
The final issue is that there just arent many people carrying any radios anymore but when they are they tend to be FRS handhelds. GMRS will receive and talk with those on the same channels. If you were calling for help, the chance of someone hearing you is probably slim but better on FRS/GMRS. Remember that you could be the person who HEARS someone needing help too, perhaps a hiker, camper or kid on an FRS portable.
The only time I see CBs anymore are on big trucks or on offroad jeep types.
If I were doing the backroads, I'd probably have both CB and GMRS/FRS.
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RIP Bob Hoover https://www.thesamba.com/vw/forum/viewtopic.php?t=427791
Hoover Sermons: https://www.vwsage.com/images/vwsage/Bob%20Hoovers%20Sermons.pdf |
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nemobuscaptain
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nemobuscaptain
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nemobuscaptain
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| Posted: Sat Nov 30, 2019 4:18 pm Post subject: Re: CB Radio what setup do you have? |
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| Steve M. wrote: |
Waking up this old thread to ask how big a ground plane or the minimum size that would work?
I am not cutting any new holes to mount an antenna and I have a 3/4" ply roof rack on top.
I'm thinking I can put a piece of thin sheet screwed into the bottom side of the plywood and cut a hole through the plywood to attach the antenna.
Or put a piece of sheetmetal on the bottom side of the Westy cargo box and mount the antenna in this location.
The antenna would probably be a K40, (if they still make them.) |
The ground plane needs to be basically the length of the antenna. The ground plane provides the other part to get to half of the wave length (roughly 203 inches for CB) through some electrical magic.
Remember that the metal roof running under the fiberglass can be your ground plane... I think. This is the part Im unsure of. I know you can't use the fiberglass as your ground plane, and I'm pretty sure you can use the metal below it.
Before I've done what youve suggesting, added metal (actually just radial rods going in four directions) on ambulances but these had just the fiberglass top, no metal nearby to use as the groundplane.
If I were to cut a hole in the westy top cargo area, it would be on the corner so I could use that long run of roof metal/drip rail on the side to give me the remaining wave length needed.
If it were me however, I'd probably do a drip rail or hatch mount raised enough to get the antenna at roof height first. Something like these:
Drip rail mount:
hatch mount:
If the images disappear later, google something like "hamstick on a hatch" or "hamstick on a driprail". I think all the CB type firesticks are NMO mounts but frankly if you google firestick, you get a whole lot of stupid and poor installs. Hamsticks will show you the mounts by people that have a clue about radio frequencies (and like tested them with meters for standing wave). Also google adding a "ham adding a ground to a hatch" or driprail mount. The ham antennas can sometimes be gigantic though as they are trying to operate on antennas that may need a giant antenna (or a giant load coil to compensate).
This is good reading too: http://www.k0bg.com/antmount.html
Note that the bumper type mounts are mounted on a post to get the antenna up above the metal of the body but how many of us are willing to live with something like this? A post to raise a firestick above the body doesn't need to be this huge, but Im guessing not many are willing to live with something like that.
This is a GREAT setup on a bus:
| kourt wrote: |
Dual band 144MHz/440MHz antenna mounted on driver vent; height can be reduced easily. |
If you are going to go to the hassle of drilling a coil mount, it should be high like this, not down on the body like I've seen.
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kourt
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Joined: August 13, 2013
Posts: 1946
Location: Austin, TX
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| Posted: Sun Dec 01, 2019 5:14 am Post subject: Re: CB Radio what setup do you have? |
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| nemobuscaptain wrote: |
That is a cool rig and antenna. Im sure you know that some people modify those 857s to transmit on CB freqs, despite this being technically illegal.
Your antenna is very directional from there. Obviously your antenna will be blocked to the front but also the antenna itself will detune because of that vertical piece of metal running vertically just inches from the antenna. Generally you want the antenna to be at least 45 degrees from the metal. Im sure the yaesu tuner can compensate but you are wasting much of your rf as heat in the tuner instead of radiated power. If it's a 4 watt CB inside the bus, that can be a problem.
It is secure though and I know some think that is the most important.
I suspect you'd be better off with a shorty mounted on a drip rail or on one of those hatch mounts (assuming a good ground) than that 102 mounted on a bumper. |
Howdy,
The 857, like all of my radios, is freebanded. And despite the general fearmongering, it's not illegal for an end user to modify and use radios out of their designed bands (the illegality is related to what the manufacturer does, not the end user). I can scratch build a radio to work on CB or amateur radio, and in the US the courts have supported the end user's right to modify manufactured equipment in the same context.
Yes, the 102" behind a giant steel bread loaf is a compromise, but its 1/4 wavelength is still a great performer on anything 10 meters to 40 meters. What I've found, though, is that if I bend it back I can also get some great NVIS performance out of it.
The poster above refers to my engine vent antennas--I have one on each side--and those are used for up to 50 watts on VHF/UHF. I'm running repeaters in Austin and I can hit those repeaters with my van vertical antennas up to 80 miles away--very effective.
I use my Westy as a rover for VHF/UHF contests, so antenna building is a way of life for me.
kourt
roof rack: (L to R) stacked 144mhz square loops, stacked 440mhz wheel loops, 6m square loop
hitch stack: (top to bottom) 6M moxon, stacked 2M beams, 222mhz beam, stacked 440mhz beams
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Steve M.
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Joined: July 30, 2013
Posts: 6832
Location: Fort Lauderdale, Fl.
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| Posted: Sun Dec 01, 2019 5:31 am Post subject: Re: CB Radio what setup do you have? |
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| kourt wrote: |
I use my Westy as a rover for VHF/UHF contests, so antenna building is a way of life for me.
kourt
roof rack: (L to R) stacked 144mhz square loops, stacked 440mhz wheel loops, 6m square loop
hitch stack: (top to bottom) 6M moxon, stacked 2M beams, 222mhz beam, stacked 440mhz beams
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How much wind noise do you experience with this setup and have you noticed an effect on gas mileage?
Or is this a stationary setup for only when you park it?
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Steve M.
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Location: Fort Lauderdale, Fl.
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| Posted: Sun Dec 01, 2019 5:36 am Post subject: Re: CB Radio what setup do you have? |
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[nemobuscaptain]
Thanks, that's the answer I was looking for.
If I put a square of sheet metal on the bottom side of my plywood roof rack as the ground plane does it need to be electrically grounded to the vehicle or would you get the benefit of the ground plane just by being there?
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Vanlife Geek
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Joined: September 19, 2014
Posts: 285
Location: CO
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| Posted: Sun Dec 01, 2019 9:28 am Post subject: Re: CB Radio what setup do you have? |
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| kourt wrote: |
I use my Westy as a rover for VHF/UHF contests, so antenna building is a way of life for me.
kourt
roof rack: (L to R) stacked 144mhz square loops, stacked 440mhz wheel loops, 6m square loop
hitch stack: (top to bottom) 6M moxon, stacked 2M beams, 222mhz beam, stacked 440mhz beams
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Ground control to Major Tom! 
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1986 Syncro Westy
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1983 Westy
1981 Westy
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nemobuscaptain
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nemobuscaptain
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| Posted: Sun Dec 01, 2019 10:55 am Post subject: Re: CB Radio what setup do you have? |
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| Steve M. wrote: |
[nemobuscaptain]
Thanks, that's the answer I was looking for.
If I put a square of sheet metal on the bottom side of my plywood roof rack as the ground plane does it need to be electrically grounded to the vehicle or would you get the benefit of the ground plane just by being there? |
The antenna must be grounded. The ground plane doesnt. It s is probably the same thing though, but there can be a slight gap between antenna and ground plane (ie a drip.rail mount).
Again radials work just fine, if you insist on mounting to the pootop section, like this:
Commercial: https://www.amazon.com/Pro-Trucker-Ground-Antennas-Similar/dp/B01H7RDX48
Again if you are cutting through the luggage rack fuberglass and mounting to the roof, the roof itself is your ground plane.
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Last edited by nemobuscaptain on Sun Dec 01, 2019 12:37 pm; edited 3 times in total |
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nemobuscaptain
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kourt
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Joined: August 13, 2013
Posts: 1946
Location: Austin, TX
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| Posted: Sun Dec 01, 2019 5:43 pm Post subject: Re: CB Radio what setup do you have? |
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| Steve M. wrote: |
How much wind noise do you experience with this setup and have you noticed an effect on gas mileage?
Or is this a stationary setup for only when you park it? |
Howdy,
The wind noise is not noticeable above normal Vanagon driving noise. It does not have a significant effect on mileage. This setup endures 80MPH road speeds. The mast on the back of the van (in the trailer hitch) is raised to a height of 25' only when parked. In the picture it is shown in the driving configuration, about 13' tall.
kourt |
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rmcd
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Posts: 1349
Location: PNW - its a dry rain.
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| Posted: Tue Dec 03, 2019 10:39 pm Post subject: Re: CB Radio what setup do you have? |
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Wow. Great knowledge shared. Thanks. I’m just getting started. I was going the route of the Vanagon life mount. I have a cable pulled from dash to rear vent for future radio.
Based upon what I think I’ve understood from this thread is the VanagonLife vent mount antenna is a good approach but maybe should have the antenna mounted a touch higher? Or would this height and separation be good enough for most frs/gprs ?
https://www.vanagonlife.com/theshop/vents
Thoughts.
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Corwyn 
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Location: Olympia, Washington
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| Posted: Sat Dec 07, 2019 10:16 am Post subject: |
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| Jeff's Old Volks Home wrote: |
At the risk of sounding ignorant. What's the advantage of having a CB nowadays with a cell phone in every pocket?
Jeff |
I'm installing a CB for use in Baja California - all the RV convoys use them. The FMRS radios have crap range; a handheld VHF has crap range. In a caravan, you can pick a channel and get better range. Many places don't have cell coverage.
This one is in most of the logging trucks in the PNW:
https://www.amazon.com/Cobra-75-WX-ST-SoundTracker...amp;sr=8-7
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IdahoDoug
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Location: N. Idaho
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| Posted: Sat Dec 07, 2019 10:35 am Post subject: Re: CB Radio what setup do you have? |
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I carry a simple handheld CB, which has terrible range, just for emergencies. I used to carry a magnetic mount antenna I could put on the roof, but it eventually got damaged and tossed.
We have benefitted from having it many times, most often simply being caught in a huge interstate traffic jam. When we find ourselves in it, I can easily communicate with a nearby semi truck to find out what's going on so we can decide what to do, while all the cars around us are clueless. Being mobile, I've also used it to spot others on a trail, and I've always thought it would be useful in a major utility outage to have a communication option.
I also like that I can move it from car to car, depending on which vehicle we're road tripping in - even a friend's car. For instance, we are driving cross country for Christmas and it will be in the glovebox of the Outback.
One time we were caught in a huge blizzard coming home from a ski trip in Salt Lake City to N. Idaho through Montana. One of the worst I've decided to drive through. With traffic moving on the interstate at 10-15mph and confined to the tracked right lane, we were able to keep track of how far ahead the highway patrol had closed the interstate. They closed the Southbound lanes and were working on closing the Northbound exits one at a time. Since we were fully chained up with high clearance, ice tires, food, water, shovel, winter gear and CB communication, we opted to continue by staying in the untracked left lane at 25mph. It had about a food of accumulation and we passed thousands of stranded cars over a 5 hour period, knowing via CB it was still open ahead of us. We eventually drove out of the storm, and credited the CB with that decison.
It was also entertaining, with the trucker's comments keeping us all laughing. Of course they were profane at times but I warned the kids.
Anyhow, some input for those who don't want a dedicated bolt on that there's merit in having at least a handheld in the bottom of the glovebox for emergencies. Mine takes AA batteries because I know I can find them at every gas stop, or hardware store.
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nemobuscaptain
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nemobuscaptain
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| Posted: Mon Dec 09, 2019 12:28 am Post subject: |
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| Corwyn wrote: |
. The FMRS radios have crap range; a handheld VHF has crap range. In a caravan, you can pick a channel and get better range. |
FRS and GMRS are two different radio services though they share frequencies and can (sort of) communicate between each other.
FRS has very low power (like half a watt I think) and come with a crappy little nub antenna. Their primary usefulness is cheapness and tiny size. A walkie talkie is never going to.work particularly well w an antenna inside a car, easentially a Farraday cage.
GMRS can be a walkie talkie or a veh radio. Obviously it can have an extenral antenna. It can transmit up to 50 w and will provide reliable comms much farther than a CB handheld and most mobile CBs (both 4 watts) zero doubt in my mind.
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