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Maco v5/8 won't tune

D

distortion

Active Member
Jan 1, 2006
106
1
26
atlanta, ga
Having an extremely hard time tuning a maco v5/8 in.. It worked fine at my house, moved it to my dad's house and it hasn't been right ever since.

All vertical elements are 6", for a total of 240". We've tried everything from 235 to 245 adjusting the top element.

All horizontal elements have been 4", and 6" per a thread by Master Chief.

The ring is 1" at ends, ignoring the screws.

6 1/4" from the wired clamp to the outside clamp.

What can I try? Is it possible that something in the matching network is astray?

The symptoms are: You can tune .. say for instance, channel 13 to a 1.1 SWR. However, it's extremely narrow banded.. by the time you get to 20-25 it's around 1.7-1.8.

Thanks,
Josh
 

Let me also add that this antenna has been pretty close before.. I had it at a 1.1-1.2 over all 40 channels.

It also has been in the tree with around a 1.2 on 13, and a 1.4-1.5 over the rest of the band.. which is why we took it down after only a few weeks of use to try to dial it in better.

Brand new 213 has been tried, brand new lmr 400, etc. It is not a coax problem.

Thanks,
Josh
 
What meter are you using to tune the antenna?

You seem to have the wire on the right side of the ring but the bandwidth issue is bothersome.

Don't get hung up on the 240" and 6 1/4" measurements. Those will end up being what works best.

Post a picture of the base section and let's see what you have going on.
 
Recently a ratshack SWR meter.. but all day today I was using a friends mfj 259 advanced. I do not have a digital camera at this time, unfortunately, as I have lost the chord :( I have a new one on order.

I will try to borrow one. I have changed the total length a ton 235-240+ with no real effect. I get the swr low on whatever channel I'm tuning for, but it is still extremely narrowbanded.

I am tuning the antenna on a 10' mast, per the instructions, with no metal surrounding it..

Thanks,
Josh
 
make sure you have good electrical contact and clean surfaces at all connection points. Sometimes the elements are not making good contact, and also make sure the bottom mounting tube is not shorting with the vertical element where it goes inside.
 
you sound very close Josh and not very far off , you have the clip and the wire that you can slighty move in either direction , IM not a perectionist when it comes to those antenna's. Some say the top element of the antenna needs to be longer or shorter at times , but you are very close like I said in the beginning. Usually when as close as you are it's the clip ,kind of like a fine tuner in your case. And as far as the top section goes , (not always the easiest to get to) I've shortened the bottom section and it worked just fine. My numbers on those antenna's were always fairly close with the 1/2 dozen or so I've dealt with over the years. My numbers were usually 1.3 on 1 1.1 on 20 and 1.3 on 40 give or take a notch or 2 on either end , your only on a 10 foot mast , my guess is this , if you were 5 or 10 feet higher , those numbers would change even though you say you have clearance all around you. Your very close Josh . Are you from the ground or roof ? You say you have had good matches before with it ? Is the mast a new addition to the antenna ? If so , you might isolate the mast from the antenna itself (piece of rubber of some kind or something along those lines) as I said , your close as it is and as long as your not running mojo power , you should be fairly good to go. Good luck to you .........oh yeah ! better you then me. :?
 
Just remember, the SWR curve generally makes a U shape.

If the bottom of the U is something like 20 channels below CB channel 1, then CB channel 1 might show a good SWR, but the SWR would continue to rise as you went up.

CB1 and CB40 should be the same SWR with the bottom around CH19.

So you need to move the clamp around a bit and maybe make the antenna a little shorter.

Also make sure there is no other obstructions or antennas near by, and that the mast is grounded well.
 
Thanks for all the advice, but I have found the issue. I will post details later, maybe it'll save someone some problems in the future, but as for now I'm at work and don't have time.

Josh
 

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