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   Home   Help Search  
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Author Topic: Mobile Antennas  (Read 2903 times)
N4BAM
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Posts: 36




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« on: June 05, 2013, 03:57:58 PM »

Greetings,

I have a 1 ton Chevy Silverado Dully for my 5th wheel RV. I'm mounting a ICOM IC-7000 (no amp) and am very new to Amateur Radio.

I have to mount the antenna(s) on a home made steel bracket just behind the crew cab so as not to interfere with the movement of the RV.

I have two antennas that I want to mount on this bracket about 3 feet apart (each side of the bed, Just below the roof line).

One antenna is a Little Tarheel II for 6 through 80 meters and the other is a Comet SBB7 for 146/446 MHz.

Will I have any problems with these antennas being about 3 feet apart on a steel bracket?

If so, any suggestions? I am trying not to drill any holes in the vehicle, my other option can be to mount an antenna on my front bumper with a bracket.

Thanks in advance,

Gunner
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Best, Regards,

1SG Terry "Gunner" Peterson Jr. USA (Ret)
OIF  2003
N4BAM
KH6AQ
Member

Posts: 7718




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« Reply #1 on: June 05, 2013, 04:39:51 PM »

There should be no significant interaction between the two antennas. They will work fine.
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W4TRJ
Member

Posts: 19




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« Reply #2 on: June 05, 2013, 06:36:49 PM »

Gunner.

I dont have quite the same situation as you (05 F350 with service body), but:

- read all the articles on K0BG.com.

- Read them again

- Go to http://gacopper.com/ and get some 1" strap, go to a real auto parts store (not autozone or similar but where they have real live parts men who know their business, all small towns have one of these, most big cities probably dont) and get some copper battery lugs for #8 wire and make some ground straps to suit. You'll need a honkin' gun to heat these up. I use a Weller 240 watt. Works beautifully. I measure for 2 or 3, whatever I can reach laying under vehicle, and then go make them up, and let them cool, and install them.

- Run ground straps as indicated in K0GB's articles. Take your time. You'll probably need minimum 20' of strap, and I would get 30'. I bought 10' and didn't have enough.

- Buy the copper lugs in box of 10. Cheap considering what they are. Crimp and solder.

- Study the part of K0BG about winding the chokes near the base of the antenna. Order ferrites from DXengineering. Follow Alan's instructions. It seems like smoke and mirrors, but it makes a difference. I can't explain why. I get it, sort of, but it's one of those things where you just have to have faith.

- I've only got hamsticks so far, so I can't address the Tarheel, tho Alan does (k0bg).

- The info he presents is somewhat massive, and somewhat convoluted, because the info itself is convoluted. There's lots of variables. You can only eliminate so many. But you can eliminate alot. The difference between rf ground and dc ground is very important, and very vague in terms of presentation.

- If you live in a city or near power lines, you will be discouraged at the noise level you will get. Do the work, then get the truck out on the interstate away from power lines and see what you get. In city/urban areas I get S8. Interstate away from power lines I will get S2, no worse than home rig. You will pick up every caution light and blinking light known to man. Cant be helped.

- On your power lines: Maxifuse. At your real auto parts store.

- Anderson powerpole connectors. Get the crimp tool or make friends with someone who has one. Search web.

- It's not a "hook this up and be done with it" type project. It's vague, somewhat frustrating, and somewhat laborious. If you're not into details, don't start. God is in the details, and if God aint there the devil will be. Pay attention. Be meticulous.

- Get an antenna analyzer, borrow, buy, whatever. You will find it useful. Rigexpert AA-54 is a mighty fine choice. I borrowed an MJF and there is a difference in the two units, and the difference is worth the extra dough.

- Read K0BG.com, again.

Good luck.

DC

















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N5TWB
Member

Posts: 50




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« Reply #3 on: June 06, 2013, 02:18:18 AM »

^^^^^ Dittos to what W4TRJ wrote!!!! Especially the part on multiple readings of Alan's website and proceeding as directed there.

Creating as much space as practical between the HF antenna and the cab will make things easier. Also, you don't say so I'm going to assume you are choosing to mount the V/UHF Comet behind the cab because of potential clearance problems with a roof mount of a tall antenna. If that's so, I'd recommend you consider one of the shorter dual-band antennas, say a Comet SS-460SBNMO, 19" tall with the standard NMO mount. Putting it on the roof will get it away from the shadow effect of the cab and improve performance. Of course, you still have a shadow when towing the 5th wheel but the separation helps to reduce that effect.
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N4BAM
Member

Posts: 36




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« Reply #4 on: June 09, 2013, 11:49:36 AM »

Thanks for all the good info, I appreciate the help.

One other question popped up; I was looking for a screwdriver controller for my ICOM 7000 and I believe The Better RF Company seems to be no longer in business; I have a ICOM 7000 and a Tarheel II.  Any suggestions?  Thanks in advance ~ Gunner
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Best, Regards,

1SG Terry "Gunner" Peterson Jr. USA (Ret)
OIF  2003
N4BAM
G7DIE
Member

Posts: 65




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« Reply #5 on: June 10, 2013, 03:01:45 PM »

Just get used to using the supplied controller, listen for the peak in noise when tuning the antenna, the low VSWR point won't be far from there, it'll become second nature in no time at all, you'll get to the point when you won't have to listen to the noise, a bit like knowing when to change gear on a stick shift car, it just becomes second nature Wink
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