Gents, bought a used replacement antenna for my car while on a layover in Billings Montana.  Got it for $20 but not sure it works or how to test it.  

See below pics of the antenna and the connector.  I did a little research before posting and this is what I learned.  The connector has three wires. Black, Blue w/ red stripe and Blue w/white stripe.  The threads I read said both Blue wires are positive and one sends it up and one send it down.  The black is obviusly the ground.  So my understanding is just connecting a 12v battery to the positive on either blue and the ground on black should activate the antenna up or down.   Does anyone know for sure before I end up damaging the antenna.  Also if its not working are these things repairable?  Thanks 

you can ohm it out. find the ground for sure it will have  the same resistance between either of the hot leads, the two hot leads will show the greatest resistance between them. Hopefully the nylon cord is intact.

Hot to Hot hightest resistance reading

Hot to ground lowest other Hot to ground lowest and matches 1st Hot to ground.

 

Edited April 11, 20196 yr by Dave WM

Dave,
It shows a short no matter what connection I make. Similar results if I touch any lean and the body of the antenna.


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Disregard....I had my meter on the diode function not the resistance function....duh!!!
25 ohms across ground to either blue wire and 1 ohm between the blue wires


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Well, motor runs but the antenna doesn’t move on either lead. Looks like a $20 paperweight.


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Well not exactly a paper weight. There are members of the forum that have repaired some. 

Can you pull on the tip while running it? Also I cant tell which model it is. Sum have raising lead and lowering lead. Try switching the power lead and gently help the antenna out?

PS di you buy it on ebay? Did you pay more than $50? 

23 minutes ago, Av8ferg said:

Well, motor runs but the antenna doesn’t move on either lead. Looks like a $20 paperweight.
 

No worries, its repairable, especially if the mast is in good shape and not bent / broken.

Problem is likely with the nylon line on the spool that moves the antenna mast up & down.  Also could be the clutch adjustment.

Easy to dissemble,  pay attention, make notes of the assembly order of the bits & pieces.

Working on one right now.   

BTDT. its not too hard a fix if its just the broken nylon cord. You need to get some heavy duty weed whacker smooth round .15 IIRC. the size is tough since the stock stuff is between the diameter that you can buy, I ended up going just a bit larger as the bit smaller keep failing after repeated use. It does not break but will fold over on itself. You need to make the clutch just enough to do the job but not so much that it wants to fold the nylon wire once its fully extended.

Bottom line is the nylon for weed whacker seems a bit too soft, but finding the right stuff long enough is hard. I tried buying a few OTS power antenna repair kits, they had the right cord but were too short, the Datsun has a LONG antenna.

FYI the ohm reading sounds odd, 1ohm between the hot leads does not sound right. Try it again and this time reverse the polarity of the meter. I would think it should be closer to the sum of the two hot to ground or 40 ohms. I assume you got it running and was able to reverse so the matter is moot, but I just don't like mystery.

 

Edited April 11, 20196 yr by Dave WM

So, it appears the last portion to the telescoping portion is damaged. I pulled on it while running the motor and it pulled out of the rest of the receptacle. So it definitely not whole now. Maybe I can use parts from another one and rebuild this thing.


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the tip of the cord fits in by heating the antenna up enough to shove in a new nylon cord, same with the retainer part on the reel. Keep the nylon cord as a guide to know how long you need the weed whacker line.

again you want the stiffest nylon you can find, and will prob end up with a diameter that is just a bit more than the stock. I will dig around and see if I have any left (I know I do but where is it is another matter all together).

Looks like the cord is a problem,  The spool end has a metal tip with a hole that a tiny screw goes thru to keep it on the spool.

Dave has given you all the good tips ....