1-14 thread

Apr 03, 2016 57 Replies

I need to mount a GPS antenna. It has a 1-14 internal thread. 3/4" electrical fittings are similar, but they are .050" over 1". I need to thread something to fit. Can you thread the O.D. of 3/4" PVC pipe, or will the threads be too rough when you finish? I don't want to pay $11 for a piece of PVC with the thread that is made to mount one on a light bar.



Mount:

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Antenna:

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I may have some 3/4" aluminum conduit left, but I don't have a 1-14 die.


Does it need to be made of PVC, that sounds dicey to me.

Acetal is a great material if you need easy machining and no conductivity.

"Michael A. Terrell" wrote in news: snipped-for-privacy@earthlink.com:

Find a tube its a slip-fit over. Shim with tape if its wobbly. Drill near the bottom edge of its threaded socket for a self-tapping retaining screw.

If this is 3/4" NPT thread (14 tpi, nominal OD 1.05"), just use a PVC threaded nipple; most hardware stores can supply that. The thread is tapered, the leading parts of the thread will fit in fine, it'll get tight deeper...

Threaded nipples are NPT, tapered; the electrical fittings that don't fit, are NPS, straight.

The thread inside the antenna is straight, and a pipe taper will only go in about one turn before I would need to use wrenches on it. The pipe thread starts .050" larger that the internal thread on the antenna. It is the same 1.050" start of the taper on both water and electrical 3/4" fittings, or I would have already put it up. :(

Invest $14 in a die on eBay, make 20 of the things, sell them for $9 each on eBay, and you'll come out ahead AND have the die for the future?

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Do you have a pipe tap? I'd open the female threads up, myself. Also, I've seen malformed threads (crest too pointy) that come on plastic threaded items, and have fixed a lot of '"it's too tight" issues by whittling the crests down. Steel doesn't flow like plastic, so the made-for-steel taps and dies don't create those pointy crests except on PVC.

And the vaunted Gunner comes pirouetting out onto the stage to entertain us yet again.

We are told that 3/4 pipe has an 3/4" O.D. and it takes metric gears to thread 14 TPI.

Will he ever stop amazing us with his wisdom?

Are we to assume you don't have access to the obvious solution, a lathe?

--jsw

No, I don't. I have been trying to pick it up for several years. At first, he didn't have 'the time' to dig it out of storage, and now that he has dug it out I don't have his new home address or a telephone number. If I did, I would have already tried to make one or maybe a dozen, while it was set up. All I get are vague directions like, "He lives down there on the left, on the four lane..."

It is an old Atlas lathe that also needs a few gears, but there are a lot of different gears for that series, on Ebay.

I would rather have a properly threaded mount, than a modified antenna, in case it needs to be replaced in a hurry. This is a standard Marine GPS antenna but the boat mounts are overpriced and don't lend themselves to this application. There is one more problem: The molded threads bottom out right against the coax. By the time a pipe tap was deep enough, the coax would have been chewed off. The housing is completely glued shut, and there is no way to replace it. I have another type of GPS antenna with a built in down converter. (Meinberg, output is at 35.4 MHz) but it only works with a PCI card (Meinberg GPS170PCI) that goes into a computer. You can have up to 700 meters of RG-58 between the antenna and the PCI card.

The system that I put together will run off of about 2A @ 12V DC. It is built from components from old Cell tower sites, and they were removed during upgrades. It provided both frequency and time signals for the site.

Well, I have threading dies for 3/4 pipe, would be willing to bet (1) a hardware-store nipple in PVC has enough bulk to hold, (2) chasing the threads on the hardware-store item would reduce it enough to fit. You DID get a few threads to engage.

Alas, if you need true 1-14 straight threads, the best I can suggest is an allthread rod in stainless (McMaster has 'em, but not at a friendly price). That's gonna mean, though, that you have to make a tube out of it before your cable fits. It's not clear that the 'pipe nipple' PVC item has the right clearance for a (?BNC) coax connector, either.

1-14 die at MSdiscount.com runs a little under $18 (USD). Trying to use it on PVC is gonna be sticky: soapy water might help.

That mounting thread is standard marine thread for antennas and has been for decades. I have an old vertical antenna from the 1960's that I thought was for the old 2 MHz marine band. Antenna analyzer shows it's a CB antenna.

You should be able to find what you want at any marine electronics shop.

Paul

I haven't found a mount to do what I want it to. There aren't many marine electronics dealers this far inland, and what I've seen online just won't work. The last one I found was a small shop in the Florida panhandle, around 1990 when I was building a TV station in Destin. :)

Right past the old blue barn that used to be there.

No, they like to use names of businesses that closed more than 25 years ago, or the original street names in use before the county decided to number almost every street. It's just as bad. :(

Tries to put you down? Goodness gracious no., Just trying to shine a little light on the problem.

But how in the world could anyone put you down further then you are already. You can't pay the taxes on your shanty, you used to have $10,000 in the bank, but not now, you would have died except for what might be called "socialized medicine".

Wake up man. You are the bottom of the pile.

Did you look at the link I posted for the marine GPS antenna? The coax exits the side of he base, right above the threads. I would have preferred it to go straight out the treaded hole, but Marine antennas don't mount that way :(

Yeah, same/same. It sucks to be offered a tool you need and not to be able to pick it up. BTDT.

Want to get outside more, chopping wood for the winter, Mikey? (Does Flowda even _do_ winter?)

Well, now you can, and it won't hurt at all.

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Just watch out for the nasty pink balloons. They're _lethal_!

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