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Author Topic: Strange dual-band mobile problem  (Read 8953 times)
KI4SDY
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Posts: 1452




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« Reply #15 on: September 12, 2010, 07:50:35 AM »

K3GM

I don't think many hams are going to be buying 1,000 foot spools for a mobile installation. Not only do smaller rolls of cable come boxed but also sealed in plastic bags with instructions on the outside such as "do not bend!" I guess if you buy commercial length rolls they figure you might know enough to install it correctly and that instructions are not necessary, or are they?  Roll Eyes

As to your second comment, there are other forms of radio communication than ham radio. I have been using many different services since I was 10 years old, commercial for our family's agriculture business, marine for our boats and CB for other local communication. I addition, I have 25 years of public safety communications under my belt, so what is your point?  Kiss

KOBG

I have cheap Radio Shack 8X installed on an exposed stud mounted antenna bolted to a tool box. It has been on there in 100 plus degree Florida heat for almost five years now with no problems. It has not "migrated" anywhere. So what is the difference? The difference is through good planning I made sure not to bend, pierce, cut or abraid the coax. If you install things correctly they work well, if not, you get bad results.  Roll Eyes

All these eHam.net "experts" and not one knows how to properly install something simple like coax. Sad, isn't it?  Cry

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KE3WD
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Posts: 5694




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« Reply #16 on: September 12, 2010, 02:40:58 PM »



All these eHam.net "experts" and not one knows how to properly install something simple like coax. Sad, isn't it?  Cry




Uh, yeah, right, that's what it must be alright. 

Not one of us.

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K0BG
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« Reply #17 on: September 12, 2010, 04:14:10 PM »

Gull lee Vern, jest mae be yo' rite!

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K5LXP
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« Reply #18 on: September 12, 2010, 08:20:46 PM »

Looks like even CB'ers aren't fans of 8X:

...we do not recommend it for mobile installations. We prefer the plastic types (polyvinyl, polypropelene, etc.) because they are just plain tougher.
... Polyfoam insulation deteriorates faster than the plastic types and also tends to collapse easier than the plastics when pinched or sharply bent.

<http://www.firestik.com/Tech_Docs/coaxtalk.htm>


Sometimes you can't always guarantee optimum conditions during installations, and there being no performance advantage to 8X there's no point in using it and creating an opportunity for a problem down the line.


Mark K5LXP
Albuquerque, NM

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KI4SDY
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Posts: 1452




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« Reply #19 on: September 12, 2010, 10:16:44 PM »

Is that where you get all your information from, CBers? Somehow, that doesn't surprise me a bit! However, you do need to pay attention to their instructions about cable not being pinched or sharply bent. That was what I was trying to tell you and your other eHam.net "expert" buddy before, but you weren't listening. Even CBer's know your not supposed to do that!  Wink

If the cheap 8x I used ever wears out before I pass on, I will let you know.  Cool

By the way, if you will go to speecharts.com you can get some help with the diction problem you displayed, unless that was supposed to be some type of joke.
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KE3WD
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« Reply #20 on: September 13, 2010, 06:55:52 AM »

Betcha K0BG's 440 is working...
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K0BG
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« Reply #21 on: September 13, 2010, 07:05:31 AM »

You betcha it is Clark.
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K1DA
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Posts: 480




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« Reply #22 on: September 17, 2010, 09:08:56 PM »

   Top of the line UHF public safety vehicle  roof installs often use  small  RG174 size  semiridgid hardline which is easier to snake, and tends to hold up better than the soft stuff.  There are N connectors which will accept it.

   My dual band antenna was pieced together from  a small  Larson magnetic   800 mhz cell phone mount and  a   Larson dual band with the whip itself  coiled a 1/4 wave up from the base.   The coax  terminates with an SMA.  I believe Larson sells an amateur packaged  version of this with a Pl 259  and the same whip  for ham use.  Looks fine on the Bird.  (I don't want to start a wattmeter flame war but you get what you pay for on UHF)  The coax is unmarked.  Don't know if the coax  is anything special  though it was intended for 800.  I find UHF works well in urban areas where the repeaters are close by.  You don't really need  a "high gain" - down on the horizion- radiation pattern for that. 

 
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KC8OYE
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Posts: 297




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« Reply #23 on: September 22, 2010, 09:57:40 PM »

something to consider with mobile feed lines too is not using solid center conductors. .and certain kinds of foam insulation as they are prone to fatigue from vibration. even if it's just a short length of coax that's able to move back and forth a few mm.. .after a few million back and forths, it can fail.. and cause random problems.

i agree with the RG58 fans here. it's not the greatest stuff in the world for signal loss, but it's a good choice for the short mobile install runs.
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W7AYU
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Posts: 4




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« Reply #24 on: November 24, 2010, 08:55:35 PM »

I just realized that I started this thread and never posted to tell everyone how it was resolved. After all the debate on connection types, coax, etc., it turns out that the antenna I was testing was too close to another antenna on my roof. Fortunately, the second antenna was a magnetic mount antenna and could be moved/removed. After removing the second antenna, my new antenna installation worked flawlessly, and performs very well on both VHF and UHF.
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