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-   -   Homemade Uniden CB antenna replacement (https://www.badcaps.net/forum/showthread.php?t=67109)

eccerr0r 01-19-2018 05:47 PM

Homemade Uniden CB antenna replacement
 
I have a Uniden handheld CB that's missing an antenna and battery pack. The battery pack is not too big a deal because it also has a standard coaxial power receptacle.

The antenna is annoying. While it also has an RCA phono jack, using it is unwieldy.

Now it does have a 5/16" (~8mm) NEF thread (32TPI or ~0.8mm thread pitch) screw mount for an attached antenna. Anyone have ideas of what I could snag that would mesh with this, so it wouldn't be necessary to rethread it?

(Hmm... I just thought of something, the standard Schrader valve could possibly be the right threadding... might have to look into finding a dead one and gutting that.)

gabik111 01-19-2018 06:58 PM

Re: Homemade Uniden CB antenna replacement
 
I might guesing what you mean. Could you post a picture of a socket? Mini-UHF might be close.

stj 01-20-2018 01:37 AM

Re: Homemade Uniden CB antenna replacement
 
cant you change it to sma or bnc?

eccerr0r 01-20-2018 09:51 PM

Re: Homemade Uniden CB antenna replacement
 
1 Attachment(s)
No, that would defeat the purpose, would like for it to be directly attached to the radio. I think I have a couple of those RCA phono plug to BNC adapters, but having an antenna sticking out the bottom isn't quite right.

Here's the threaded receiver. I suppose this is "HF" - shorter wavelength than shortwave but longer than VHF.

R_J 01-20-2018 10:35 PM

Re: Homemade Uniden CB antenna replacement
 
Have you tried using the model number to look up a replacement antenna?

eccerr0r 01-20-2018 10:50 PM

Re: Homemade Uniden CB antenna replacement
 
And that would be homemade?

R_J 01-20-2018 11:08 PM

Re: Homemade Uniden CB antenna replacement
 
No. sorry Thought if I saw an original antenna it might give an idea of what could be home made

eccerr0r 01-21-2018 12:42 AM

Re: Homemade Uniden CB antenna replacement
 
I wasn't able to find any detailed pictures of the original antenna - though I've seen some antennas that were meant for VHF frequencies that might screw into that mount.

I figure that I will have to have some sort of ballast in the antenna as well. Unfortunately no SWR meter to tweak it. I wonder if I can use an oscilloscope (I should!) in lieu of a SWR meter...

R_J 01-21-2018 11:33 AM

Re: Homemade Uniden CB antenna replacement
 
1 Attachment(s)
The optimal antenna length (1/4 wavelength) for the cb frequencies is 108 inches, not very practical for a handheld, so it would need some sort of loading coil to have it shorter and still be efficient. I remember the RadioShack handhelds used a telescopic center load antenna. The did have a short rubber (about 10") antenna available, I think the whole length was a coil
Not sure if this is any help.

eccerr0r 01-21-2018 01:14 PM

Re: Homemade Uniden CB antenna replacement
 
I was planning to wind 9 ft of kynar 30 gauge wire onto some form, but the main issue is finding something that screws into the base... then need to attach the form to the base.

Best idea I can think of now is an old Schrader valve, anyone can think of something else that can be screwed in; then I can glue a form to that, and wind the wire onto the form.

stj 01-21-2018 01:16 PM

Re: Homemade Uniden CB antenna replacement
 
big balun wip, what is your CB band? 27MHz???

R_J 01-21-2018 02:09 PM

Re: Homemade Uniden CB antenna replacement
 
I have a Schrader valve and found a nut used to secure a control (pot) that threads on.
maybe the threaded section of a pot (brass) would work?

eccerr0r 01-21-2018 02:33 PM

Re: Homemade Uniden CB antenna replacement
 
Yes, CB is 27MHz (11m).

---

I thought standard pots were 3/8"? I grabbed a nut off of one of them and tried to mesh it against one of my car's tires (which I believe is the correct 5/16" 32TPI) and alas it's too big. The hole is visibly bigger than the receptacle in the radio. Was there also a standard 5/16" pot? Might be a mini pot or something which I don't have any of as far as I know; I'd have to sacrifice it too...

R_J 01-21-2018 02:47 PM

Re: Homemade Uniden CB antenna replacement
 
I'm not 100% sure if it is from a pot, switch or jack, I have a few in the shaft nut drawer
If a Schrader valve fits that might be the easiest, that seems to be a unique thread
That picture looks like it is a much coarser thread

stj 01-21-2018 04:26 PM

Re: Homemade Uniden CB antenna replacement
 
hold on, if it's japanese the thread will be metric.

eccerr0r 01-21-2018 05:59 PM

Re: Homemade Uniden CB antenna replacement
 
It quite possibly could be metric indeed. However it seems to mesh with 32tpi SAE thread feeler and both NF and NC (28 and 24 TPI respectively) do not mesh. A 6-32 screw meshes fine too, at least it looks like it holds flat against the wall as far as I can see.

I found that my air compressor screw-on blow gun nozzle tip will thread into this thing. And a Schrader valve cap will thread onto the blow gun nozzle!

I wonder if there are any other common things that will thread onto a Schrader valve cap?

petehall347 01-21-2018 06:11 PM

Re: Homemade Uniden CB antenna replacement
 
can you not find someone with a lathe to make a fitting for you ? or in true diy style make it yourself on said lathe ? . sorry but i suppose i am lucky with access to such tools. a die nut might even work here .

eccerr0r 01-21-2018 06:32 PM

Re: Homemade Uniden CB antenna replacement
 
Well, the other possibility is buying a die to thread out a piece of 5/16" rod, which probably is easier to access to than a fairly complicated lathe that can accurately cut out the threads (it would need to be electronically done, so this would be quite an expensive machine!)

I was hoping not to buy a die as this is a one-time deal, I doubt I'd need to cut another one I hope. The die probably would cost more than a Schrader valve :)

(also as an afterthought, a piece of steel rod is probably more resistive than a Schrader valve which are usually made of ... brass? Hmmm.)


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