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  #33  
Old 03-18-2012, 04:07 PM
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I'm out.

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  #34  
Old 03-18-2012, 04:22 PM
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Quote:
Originally Posted by 2rf66 View Post
I'm out.
Were in extra innings, you can't leave yet.



I read the post on mmm mmm mmmMaul DDD DDDDroppers.

Did he splice the cable using wire nuts and clamps?

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  #35  
Old 03-18-2012, 04:41 PM
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Oh, OK. One more, then. Here is a link that was recommended to Oatmeal for making his own cheapy connectors. I have no idea how he actually did it though. Maybe this one has enough pictures to keep Marconi from needing his hip boots.

There have been many questions on the reflectors as to what to use as connectors on cable TV Hardline

This guy claims to be using 300' of hardline with good results.
Luckily Mother Nature doesn't require our feedline to be perfect... or something like that.
Oatmeal likes this.

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  #36  
Old 03-18-2012, 05:10 PM
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If I am reading that right, he is splicing 1/2" hard line by stripping it back and twisting the center conductors together with wire nuts, then bonding the outer shield somehow with hose clamps leaving several inches of the center conductor with no shielding over it and bent away from where the shield is connected together.

Quote:
10-4, when I spliced mine together, I twisted both center wires together and twisted a wire nut on them....
For the ground, I slowly bent the wire in a angle so the 2 ends where the aluminum would touch, I used 2 water clamps to hold this in place.....
After the splice is made it looks like a up side down V..
Its all wrapped up in black electrical tape with silicone on that..
With this guy wire, you can wrap the 2 ends together and this will not allow any tention on the splice...

We really need to see a picture of that.
I have to agree with Marconi, this is not the way to splice coax, the 75 ohm impedance in that section of the line must be really out of whack.
As for it working.....ya it might work but you have to think that it is really not the way to do a splice in coax and who knows what the loss is going from one end to the other..
I think he really needs to do the test Eddie was talking about....to see how much of the power from the radio is being lost in the feed line before it gets to the antenna.
I see the advantage of putting a antenna up on top of a hill as opposed to down in a hole, or up against the side of a mountain but I have to think that if he used the proper connectors it would be way better that splicing it like that.
The W7NN Home made connectors would be a much better way to go...Don`t you think?

73
Jeff
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  #37  
Old 03-18-2012, 09:18 PM
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And just for information sake, those long feed lines (parallel feed lines) up a mountain to an antenna used to be called a 'passive repeater'. Same for those cell antennas glued to a window of a car with a smaller antenna connected to the inside of the window. They've been around for an extremely long time. In a few cases they can actually improve reception, but not in most. That deals primarily in the losses in the feed lines.
Depending on the number of those splices and how they are done, they can negate the use of very low loss 'hardline'. Not as much on HF as on VHF/UHF, but there's still a loss at HF with improper 'splicing'.
For very long feed line runs, the 'ohmic' losses can and do amount to enough that an antenna (load) doesn't even have to be connected to that other end and the SWR will look very nice. That distributed 'ohmic' loss fools an SWR meter into thinking there's a nicely matched load on the end of that cable when there actually isn't anything there.
None of all that even touches on the impedance mismatch possible with dissimilar impedance cables, or the losses associated with that mismatch.
- 'Doc

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  #38  
Old 03-18-2012, 09:25 PM
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Well,

Chest thumping and physics lessons aside...

The dude managed to talk to people with his mountainside shack, fed with patchworked cable.

That's all that matters. Guess he was not obsessed with milking out every last little drop of juice.

Probably shoulda made some better couplings though.

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Old 03-19-2012, 07:22 AM
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Quote:
The dude managed to talk to people with his mountainside shack, fed with patchworked cable.

That's all that matters. Guess he was not obsessed with milking out every last little drop of juice.
If he is talking on it, (and I am sure he is) that`s fine, I do not think anyone said it "will not" work, just saying if it was connected together properly it would be better.
I was changing antennas one time and had about 60 feet of coax laying laying out on the ground in the back yard.
Just for grins, I loaded up the open feed line ( yes un-terminated coax) with a 989C tuner and talked all over town with it.
Kind of like the shoe string dipped in salt water thing, will it work, yes.
Can it be better, most defiantly, and depending on how many splices maybe much better.
And for line length, there is a point were feed line gets so long it is not worth it.
It is even worse at VHF than HF.

I still think it would be a good test to put a dummy load and meter at the end of the feed-line and see how much power is getting through, that will tell all of us a lot.
And Oatmeal:
After you read all of this:
I am NOT bagging on you, no insult intended at all, but very interested in the results of the test above.


73
Jeff
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  #40  
Old 03-19-2012, 10:40 AM
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Line Type: Andrew Heliax LDF4-50A
Line Length: 625 Feet
Frequency: 27MHz
Load SWR: 1.2:1(estimate)
Power In: 100 W(estimate)

Results
Matched Loss: 2.121 dB
SWR Loss: 0 dB
Total Loss: 2.121 dB
Power Out: 61.363 W

Source:
Coax Calculator

Not accounting for splices, that is what Heliax will do at that length. With 'splices' over that length; even Heliax won't be much help. Depends on the kind of splice it is. Using barrel connectors, the loss will be well-tolerated. With open splices? Forgeddabout!


A lesser quality cable - let's say Times/Microwave LMR-400 will be:

Results
Matched Loss: 3.954 dB
SWR Loss: 0dB
Total Loss: 3.954 dB
Power Out: 40.238 W
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