Cut 102" for 10 Meter-For Wilson 5K

[gamegetter]

Planning to cut a 102" whip down for 10 meters for a wilson 5k mag mount to run on my mobile and wanted to run this by the forum...Measure twice and cut once! A few questions.

1. Planning to us the top half of the 102" OR would using the thicker bottom half possibly give a little more bandwidth (not too mention it should not bend as much during driving). If i went with the bottom half i would prolly have to file or grind it down a bit to get it to fit into the antenna adjustment mast but that's no problem.

I kind of like this idea of using the bottom half as this part of the whip is less flimsy and should stay up a bit more during mobile use.

OK so question 2 for discussion is on length. Planning to cut for 28.5 mHz and as per wilsons cutting guide for the wilson 5k they recommend 57 inches on their antenna cutting guide Antenna Cutting Guide | Wilson Antennas

Just wondering here if the difference in diameter of using the top half vs bottom half of the 102" whip would matter much on the length to cut in this case.

 

[W5LZ]

That cutting chart for the antenna does NOT relate to a 1/4 wave whip, only to the antenna it's specified for. don't use it to cut that 102" whip.
The way to find the resonance point for any 1/4 wave antenna is by using this formula;
234 / f (in Mhz) = feet.
so...
234 / 28.5 = 8.2 feet of about 98.4 inches.
That's a good starting point for resonance. Matching impedances (SWR) is going to be a bit more than you'll probably want, maybe 1.5:1, and that's as good as it gets unless you want to do some matching.
It's a very good idea to do the cutting of that whip at the bottom instead of the top! Cutting at the top means you loose the 'static ball', and the thing will be slightly 'stiffer' than when cutting from the bottom. That mag-mount is going to be 'marginal' at best, and a stiffer antenna isn't going to make it 'better' (knocks off easier). The differences in SWR when that thing flexes just isn't worth worrying about.
Have fun.
- 'Doc

 

[gamegetter]

it's going to be used with the wilson bottom coil mag mount doc.

basically think of it as a replacement whip for the mag mount but cutting it for 10 meters.

 

[gamegetter]

Let me rephrase.

I have a Wilson 5k mag mount. The whip on it right now is for 11 meters. I want to have a second whip so I can run 10 meters on it too on that mobile. I have a 102" whip that i can sacrifice for that project.

Wilson's cutting guide to run a 10 meter whip on that mag mount and coil recommends a 57" whip for 28.5 mhz.

Should I take the top 57" of the 102" for the 10 meter whip? or the bottom 57" of the 102" for the 10 meter whip?

P.S. this particular 102 does not have the static ball, it fell off back in the 80's, which is why it is the one i am sacrificing.

 

[BOOTY MONSTER]

id just spend 10 bucks and get another stinger to cut . grinding or filing down the 102 to fit in the wilson hole will be very tricky ... . it would be much easier to drill out the stingers hole (i did on my 10k) to accept a fatter stinger , but theres not much wall on the wilson to do that . i'd also add a inch or 2 to wilsons recommended length and then cut to tune in case tuning to your ground-plane (vehicle) needs a little extra length .

 

[gamegetter]

The top half of the 102 should fit right in to the shaft i believe. It would be the bottom half that would need a little grinding. Which I would not mind doing if there were a benefit to using the thicker stiffer bottom portion of the 102"

 

[Robb]

Booty is right about the amount of drilling that you can do to the Wilson whip mount. It is not known for being reliable even for the stock whip. Drilling it out any wider than what is there would mean that you would probably end up replacing that 'ferrule'. They fail quite often, as the set screws are in soft brass and a loose fit to begin with. Drilling the ferrule out at all would only further weaken the amount of threads available for the set screws to have. Weakest part of the whole Wilson 1000/5000 design, right along side of water migration into the coil. These facts I have witnessed myself.

 

[gamegetter]

no plans to drill out the shaft

only to grind the bottom portion of the 102' whip to make it fit into the existing shaft should I use the lower thicker part of the 102" to make said new 10 meter whip.

but only if there would be a benefit to using this bottom half thicker portion of the 102 other wise I'm pretty sure taking and using the top half of the 102 for whip should fit right in.

 

[office888]

Why don't you just get another 5k stinger?

You're creating quite a large amount of extra work for yourself.

 

[gamegetter]

i love to work

the harder the better, i am from another generation...LOL

why pay 10$ for the stinger plus prolly 20-30 dollars for shipping ( i not sure just guessing on shipping)

when i have a whip to spare right here ( i have 4 102" 's)

Does anyone have an opinion on whether there is any benefit to using the thicker lower half portion of the 102?

 

[Robb]

Does anyone have an opinion on whether there is any benefit to using the thicker lower half portion of the 102?

The risk of damage and additional part replacement outweighs any benefit you might get.

 

[gamegetter]

What are the damage that you are thinking? Is it that the mast might crack?

That lower end of the thicker 102 would have to be sanded/ground down a bit to fit into the mast.

I guess i can see the point that it would be a little bit more top heavy and possibly crack the mast, ok.

Yeah so prolly would be better to take the top half of the 102 as it nearly matches the original whip provided by wilson.

Any more in put-just keep it coming. I am not going to do it right now right away, i like to mull things over a bit.

thanks everyone for help so far.

 

[Robb]

Wilson 5000 parts

@ $15 a pop plus shipping and time lost (IF they have it in stock), if it were me I would just get a stock whip and not deal with buying another part. It is just too flimsy for what you want to do with it - IMO.


Picture: whip mast

 

[gamegetter]

Point Well Taken on the thicker bottom half

Sounds like you would not advocate using the thinner top half of the 102 either? thanks

 

[Robb]

Sounds like you would not advocate using the thinner top half of the 102 either? thanks

The Wilson 1000 I have was given to me by Russ, a forum member here that lives near my QTH. The mast was damaged due to stripped set screw mast threads when I got it. Got it for free; so who am I to complain if I had to fix it? It was also short of the whip. Had to get one of those too.

I fixed it by drilling some new holes on the other side of the mast. I put a 4-40 tap (think that is what I did - it was awhile back) and used headless Allen screws. This gave a tighter thread fit than the stock set screws have. There are also more threads, given the fact that there are more threads on a smaller screw. This worked.

But now they are frozen, even though I greased those threads very well. The mast needs replacement. Those threads and stock screws are notorious for stripping out. My idea is better; but I didn't have nor use chrome set screws. If I did, it would still be working.

If you drill out the mast to accept a larger diameter whip; then you remove even more material that the stock threads can use to hold the whip in place. This in turn will only speed up the set screws stripping out, because of less thread to hold those screws.

That is what I have seen . . .