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  #21  
Old 04-18-2008, 10:15 AM
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Hey so my HAM antenna is currenly a lip mount on the hood.. if I added a bonding strap to the firewall like you show in the pic above, would I improve my ground plane and thus improve performance?
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  #22  
Old 04-18-2008, 10:41 AM
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Where did you get the copper tape for the spark plug wires?
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  #23  
Old 04-18-2008, 12:11 PM
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Quote:
Originally Posted by nakman View Post
Hey so my HAM antenna is currenly a lip mount on the hood.. if I added a bonding strap to the firewall like you show in the pic above, would I improve my ground plane and thus improve performance?
In theory, yes. Overall performance might be subject to your ability to discern slight differences in receive and transmit quality.

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Originally Posted by subzali View Post
Where did you get the copper tape for the spark plug wires?
Here ya go, Matt!
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  #24  
Old 04-18-2008, 12:28 PM
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Quote:
Originally Posted by Groucho View Post
To which someone may ask, "Where do I actually send my money and how much?"

Mouser Electronics P/N 517-1181-1/2, page 2072, 3M #1181, 1/2" wide, 18 yard roll is $21.50/ea.

Same in 3/8" wide is $14.54 and 1/4" wide is $10.80

http://www.mouser.com/catalog/633/2072.pdf

Did not comparison shop, but Digikey, Newark, Allied, Waytek also all carry 3M products.
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  #25  
Old 04-18-2008, 03:32 PM
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So, I've got to ask the experts...

What about the "No Ground Plane" Antennas like a Firestik? That is what I went with on my LX last year because on where I was mounting the antenna (tire carrier) and the issues with grounding.

Now, I'll confess that I had, and probably still do, a high SWR when I measured it after installation. Firestik figured it was due to the 6' of additional coax (Radio Shack) I had to add to reach the dash (the 18' Firestik lead wouldn't quite reach - I was about a foot short). They state to use lengths of 9' extensions. I don't know...I think maybe it might have to do with the loop I created in the excess coax in the PS kick panel area after Nathaniel explained at the antenna building party what to do with the excess coax.

But, back on point, can a person like Drew use a no ground plane antenna and be ok?
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  #26  
Old 04-18-2008, 04:13 PM
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That magical 9' length thing is hogwash. There is no exact right length for the coax unless it's acting as part of the antenna and you definitely don't want that to happen. If you trim to the length for a clean run and the connections on each end are solid, it will not matter practically how long the coax is. Remember from the class, you have a source (the radio), a feedline and an antenna. Ideally the feedline just passes all the energy from the source output to the antenna feedpoint without any loss.

Your loop of coax would be one thing to suspect (but it would not be my first guess). I would expect to find a bad connector or corrosion, whip mount issues (like shorted to ground) or tuning. I dunno why Firestik pushes that 9/18/27 foot thing, I really don't. Only thing I can think is that they say that to cover their rear ends so that badly tuned or shorted antennas don't get high SWRs and then they have a ton of people calling and asking why they peg their SWR meters. If you short the antenna with a perfect 1/4 wavelength long piece of coax, it will act like an antenna and your SWR would actually be low even though you are not radiating much energy into space.

A no-ground plane antenna is a misnomer. a NGP antenna can utilize a ground plane, it's just that it does not need a ground plane to achieve a low SWR. NGP does not mean you can ignore your ground connections, you still need to ground the mount and radio right and have to make sure not to short anything. They are talking about the ground plane relative to the radiated energy and not physical grounds.

Wanna know more about anything or is that sufficient?

Edit: Just had a duh moment. If the antenna is a 1/2 wavelength long, then you need a matching network to achieve the 50 ohms impedance presented to the radio. If you are using a no ground plane antenna, it is 1/2 wavelength long (this is important to the reason why you don't need a ground plane). Most manufacturers that build 1/2 wavelength antennas have a matching network in the base of the antenna, which is a 1/4 wavelength (electrically) short to ground. Wonder if that's why the 9' thing. Have to mull that over some more.
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Last edited by DaveInDenver; 04-19-2008 at 06:38 AM.
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  #27  
Old 04-18-2008, 04:13 PM
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Thanks guys, I continue to learn from each of you!

Where are places to source that strap stuff locally? I really don't know where to begin. thanks!
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  #28  
Old 04-20-2008, 10:39 PM
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Well, I got this far today repositioning my antenna. I reroute the cable and wired up the CB on a new fuse panel.

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1976 FJ40 with some stuff and some leaks.

1999 UZJ 100 Series bone stock ready to rock AKA:The backup minivan

2012 Toyota Sienna Minivan, fastest Toyota in the stable.

My camping trailer build up thread.

"You 80 guys are just a Sawzall away from nirvana." -Red Chili
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