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Replace coax for VOR antenna in tail


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Hi Guys,

I’m considering replacing the 50 year old RG58 coax in my aircraft while doing an ADS B upgrade. Has anyone ever had experience with replacing the coax in the vertical stab? Specifically I’m not sure if the holes in the ribs in the vertical stabilizer will allow a pull through of new coax without taking the tail apart. Mine appears to have a balun also, which is double the size of normal coax. Any ideas?  Thanks!

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I replaced the cable from the tail bulkhead to the cockpit but I do not know about getting a new one in the vertical portion.

My problem turned out to be a loose connection on the back of the radio.  A long time chasing that ghost and cursing when I could not picu0p a VOR within 15 miles.

 

 

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5 minutes ago, KB68M20F said:

Hi Guys,

I’m considering replacing the 50 year old RG58 coax in my aircraft while doing an ADS B upgrade. Has anyone ever had experience with replacing the coax in the vertical stab? Specifically I’m not sure if the holes in the ribs in the vertical stabilizer will allow a pull through of new coax without taking the tail apart. Mine appears to have a balun also, which is double the size of normal coax. Any ideas?  Thanks!

Not sure if your antenna mount is riveted or has screws holding it on. When you disassemble, the easiest way is to pull the new RG-400 through using the old RG-58 as the wire puller. Strip back several inches of both old and new wires and physically wrapped them together (like a lineman connection) so that the total attachment is less than the width of the outer sheathing. I would then wrap it in electrical tape and pull the new wire up through the tail. 

If that fails, the other option is to use an electrician's fish tape and do it that way. I would recommend using RG-400. It is the standard today.

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I just went through this with my ‘64 D model. The cable goes from the VOR antenna down the left side of the vertical stabilizer (at least mine did). You have to  remove the left side root fairing on the horizontal stab to access the cable clamps that are attached to the aft side of the fuselage bulkhead, under the horizontal stab.  I replaced the VOR antenna at the same time with  one that has a modern internal balun. Not sure what your ‘68 will have installed.

Similar to what others have done, I cut my old cable at the bottom where it goes into the fuselage bulkhead (near the tail hinge) and joined it with the RG400 cable with duct tape and then pulled the RG400 up from the antenna. We also installed a new bulkhead fitting with BNC fittings on both sides.

The hardest part was accessing the bolt for the upper clamp on the bulkhead. Might have been easier to try to simply pull the tail of the RG400 through the old clamp without removing the clamp.

 

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9 hours ago, PilotCoyote said:

Here is the one I pulled out of mine...I replaced it with a modern VOR antenna 

...

 

F89FC742-BBF9-49F0-A4A0-D189D0EC52B3.jpeg

Durp.   I'm guessing that's the "splitter" for the nav/gs?    Will be good to get that out of there.

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  • 4 weeks later...

Hi guys,

Just as my fellow Mooney pilots advised on this post, I pulled new RG 400 from the base of the horizontal stabilizer to the top of it by attaching the new to the old. I put the two ends together, applied a piece of heat shrink, then wrapped one side with .020 safety wire, brought a piece across to the other side and wrapped it. Then I put some electrical tape over the joint to make it smooth, tested the strength and pulled it through. There may be grommets in the vertical stab ribs but it went through just fine. The hardest part was tightening the nut on the upper AN742 clamp that holds the coax in place. It was a real ball buster with difficult angles. I also installed a new cat whisker antenna with an internal balun and BNC connector. 

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