Please help id this mag mount

[dave3825]

A friend gave me this mag mount.

Overall combined height of whip with coil is about 23 inches.
The bottom radial is about 9 1/2 inch long and 0.210 inch thick
The top radial is about 10 /12 inch long and 0.047 inch thick
The coil is close to 2 1/2 inch long and 0.622 inches thick.

It has a standard pl 259 male on rg 58 U coax.

I am trying to find out what bands it is for.

Based on the coil dimensions and radial thickness, if it's for bands of non interest, could it be trimmed down to uhf / 7/800? I dont know much about coils.

Thanks

 

[duffy109]

I think CB


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[DeepBlue]

Try to find a buddy with an antenna analyzer. MFJ, Comet, etc. Those can tell you what it is for. Likely CB.

S.

 

[6079smithw]

Back in the 70's I had a CB mag mount pretty much identical to the one shown.

 

[mmckenna]

-delete-

 

[mmckenna]

A friend gave me this mag mount.

Overall combined height of whip with coil is about 23 inches.
The bottom radial is about 9 1/2 inch long and 0.210 inch thick
The top radial is about 10 /12 inch long and 0.047 inch thick
The coil is close to 2 1/2 inch long and 0.622 inches thick.

It has a standard pl 259 male on rg 58 U coax.

I am trying to find out what bands it is for.

Based on the coil dimensions and radial thickness, if it's for bands of non interest, could it be trimmed down to uhf / 7/800? I dont know much about coils.

Thanks

In reality, any piece of metal you stick up in the air is going to act like an antenna. Before you do anything, just plug it in and try it. If it works, then leave it as is.

Very unlikely it's 700/800. UHF/PL-259 connectors are not very favorable at those frequencies, and I'm not aware of any current professional radio on the market that would use them at those frequencies.

Your best approach, if you want an antenna suitable for 700/800MHz would be to cut it to be 1/4 wave on those frequencies. 3 1/2 inches long whip would put you in the right area.

You might want to confirm there isn't a coil in the base, though. If you have a multimeter, check for continuity between the CENTER pin of the coax connector and the metal base of the mag mount. If there is a coil, you'll likely see continuity between them. If not, you're OK. If there is a coil in the base, you'll need to bypass that. That would mean opening it up and removing it.

 

[dave3825]

I must say, I tried it in the truck the other day and the local 800 smartzone analog was crystal clear. I also noticed on vhf 155 mhz area, that it was receiving from a great distance. It seems to work good as is.

But if I did want to convert to a dual band uhf and 7/800, what exactly would I do? Trim the lower for uhf and trim the top for 7/800? I did not take a meter to the coil yet...

Thanks

 

[iMONITOR]

I think CB

I think you're right. It looks like the kind that came with those cheap emergency CB kits everyone had in their trunk back in the 70-80's! Basically junk.

 

[mmckenna]

I must say, I tried it in the truck the other day and the local 800 smartzone analog was crystal clear. I also noticed on vhf 155 mhz area, that it was receiving from a great distance. It seems to work good as is.

If it works, and you are not going to transmit, leave it as is.

But if I did want to convert to a dual band uhf and 7/800, what exactly would I do? Trim the lower for uhf and trim the top for 7/800? I did not take a meter to the coil yet...

Thanks

No, coils are tuned, and you are not going to be able to retune a consumer CB antenna to work well on UHF and 700-800MHz.
Ideally you'd get an NMO mount base and a Larsen NMO-150-450-800 antenna.