HIGH SWRS using riser

[SARGE]

Below are two pics of the riser I built for use with my 27" 10K. I used a drop bar for a ceiling fan and a mirror bracket. All shows to be grounded, but no matter what SWR's are in the 3's. In the pic, I had raised the mount all the way to the top and tried the 17" 10K, still no change. I had been running the 17" on the roof using a tri-mag with flat SWR's. Now I can put the 17" back on the tri-mag and all is good. What am I missing or doing wrong?


[Please login or register to view this link]

[Please login or register to view this link]

[jessejamesdallas]

Theres no way that should not be working for you, unless something is grounding out the antenna. Get a ohm/volt meter and check the antenna and see if it's grounding out. Just stick one probe to the antenna, and the other to the ground wire or your bracket...If the meter go's to reading all "0" then the antenna is grounding out...If the numbers on the meter start rising, then the antenna is OK...Could be you over tightened the connector on the bottom of the antenna mount, and it's grounding out. That is a big problem with the Predator 10K mounts, that have the screw-on type connectors...Which is another reason I use the terminal mounts....

['Doc]

At least part of the 'problem' is that the antenna's length has changed (by that 17" riser) and it's not close to resonant anymore. Yes, it will make a difference. And just for 'grins', if that riser is metal, that green ground wire(?) is doing absolutely nothing, the riser does the grounding anyway.
If you added that riser to that mag-mount, you'd see the same results.
- 'Doc

[linx]

Great answers. Try some kind of non conductive spacers between the antenna and the mount....I have a feeling you've just made that antenna a couple of feet longer and it's not liking it.

['Doc]

And naturally, after reading what I said, I didn't say exactly what I was meaning to say, so let me say it a little bit differently.
The antenna it's self hasn't changed, but the mounting position has, and how it's mounted. That can make a big difference. The same thing happens if you had an antenna mounted on the roof of your house, then slid a 17 foot mast under it. Nothing changed about the antenna it's self, but things around it did. An antenna is tuned for a specific location, meaning in relation to everything around it. If something 'little' changes, then the resulting state of 'tune' changes a little bit too. If something really big changes, then that 'tune' changes big too. Depending on exactly what changes, even if it doesn't appear to be a 'biggy', it still might be. And, just to make it complete, how close that changed thingy is can make a big difference too.
So, that ought'a about cover it (till I read it later and realize I probably left something else out, or said it wrong again.). Oh well.
- 'Doc

PS - I hate this damned time changing thing! Wake up at the 'normal' time and @#$%, I'm already an hour late.

[SARGE]

OK, so I got back to it this moring. Double check to make sure antenna wasn't grounding out (using a ohm/volt meter), all good there. The "green" wire running down the riser was placed on there in the beginning just to make sure I had a good ground to the mount. I tried placing my 102 on the riser and it like the rest showed a high SWR. I thought by placing the 17" 10K on the riser in about the same height as it was when on a tri-mag, it's SWR reading would be close to the same. Never thought it would go from a 1.0-1.1 reading to a 3.2-3.5 . I hate to go cutting on the 10K stingers as I may not find another one since Kale isn't producing the antenna anymore. With that said I guess these will now become a collector item!

[jessejamesdallas]

OK, so I got back to it this moring. Double check to make sure antenna wasn't grounding out (using a ohm/volt meter), all good there. The "green" wire running down the riser was placed on there in the beginning just to make sure I had a good ground to the mount. I tried placing my 102 on the riser and it like the rest showed a high SWR. I thought by placing the 17" 10K on the riser in about the same height as it was when on a tri-mag, it's SWR reading would be close to the same. Never thought it would go from a 1.0-1.1 reading to a 3.2-3.5 . I hate to go cutting on the 10K stingers as I may not find another one since Kale isn't producing the antenna anymore. With that said I guess these will now become a collector item!

I have done several installs on pick-ups almost exactly like you have yours, and Yes, by putting the antenna on that riser, will cause you to re-tune the antenna, since like what Doc said, "Everything around the antenna, has now changed".

But even so, it shouldn't have changed so much that you now have a SWR in the High 3's...

Here is what I would do, "BEFORE" you go cutting on that stinger...."Change out the Mount!" ...Just run down to the local truck stop, and pick up any stud mount they have, and replace that Predator Stud. The Predator studs like you have are notorious for shorting out, if the coax is over tightened onto the mount...This is why Kale got away from building them. "Kale" doesn't even recommend using one..."AND HE BUILDS THE THINGS!" (or did)

Just be sure the plastic washer is in place, so the antenna doesn't ground out to the pole.

[SARGE]

Well I went back at it and got the SWR's down some on the 17" shaft, so I placed the 27" on the riser a few inches above the bottom of the rear glass. SWR's as of right now are 1.2 to 1.4.5, not bad, but not like I had with the 17" on the roof. I will continue to try and work with it and try to get it FLAT!!!!! It started raining on me tonight and is suppose to rain all week, maybe this next weekend I can fool with it some more! I am also going to look for another L-shaped mirror bracket to use as this one does not seem to be real stable. During the process of jacking with the thing yesterday, I managed to loose one of the set screws for the stinger as it decided to fall into the opening in the truck bed for the gooseneck hitch. I had eyes on it at one point and when I tried to fish it out with a T-handled allen wrench, it rolled on out of site! Hopefully I can run into Home Depot tomorrow during lunch and find a replacement!!!

[jessejamesdallas]

Well I went back at it and got the SWR's down some on the 17" shaft, so I placed the 27" on the riser a few inches above the bottom of the rear glass. SWR's as of right now are 1.2 to 1.4.5, not bad, but not like I had with the 17" on the roof. I will continue to try and work with it and try to get it FLAT!!!!! It started raining on me tonight and is suppose to rain all week, maybe this next weekend I can fool with it some more! I am also going to look for another L-shaped mirror bracket to use as this one does not seem to be real stable. During the process of jacking with the thing yesterday, I managed to loose one of the set screws for the stinger as it decided to fall into the opening in the truck bed for the gooseneck hitch. I had eyes on it at one point and when I tried to fish it out with a T-handled allen wrench, it rolled on out of site! Hopefully I can run into Home Depot tomorrow during lunch and find a replacement!!!

This is where it's nice to have one of those magnet thingy's on a stick, to fish out screws that fall where your hand won't fit!

[SARGE]

Sorry JJD, I somehow managed to leave out the part where I magnatized my T-handle allen wrench. Yeah I use to have a small magnet on a stick till someone borrowed it at work and failed to return it, guess they were too cheap to smend like $5.00 on one themselves! I hope mine breaks off and stabs them in their hand, would serve them right!!!!!!!!

[SARGE]

Well I ran with the 27" 10K today and after talking to my two local friends, the radio still does not sound 100% like it did before (1) I changed the antenna location and (2) had the issues with the squealing, which wound up being the fault of the external speaker shorting out inside the case. Before I was running the mic gain at 3 o'clock and this evening I had to cut it back to 11 o'clock for it sound anything like it use to prior to these issues. I did have the radio and amps checked out after the squealing began just for some piece of mind. I don't understand why the radio sounds different now, unless it is due to the fact that the SWR's are not nearly as "flat" as they were on the 17" when mounted on the roof using the tri-mag?

['Doc]

SARGE,
This may be because of my just not understanding how something was said. So, if so, don't pay any attention to it.

An antenna can't, and doesn't affect the audio of a signal. It radiates whatever signal is sent to it. If the audio of that signal has changed, look somewhere else besides that antenna for the reason for it.
Now if that difference in audio is actually a difference in 'loudness', sure, I can understand and agree with that. That's from the 'amount' of signal being radiated. Lots of chances of something being misunderstood because of how it's said. Then, you're changing the mic-gain has a bit to do with it too.
Good luck.
- 'Doc

[preacherman]

Hi Sarge...
One other issue is that the antenna doesn't have nearly as good a ground plane
now as it did with the trimag mount. It's going to be a bit more directional
now...better toward the front than the sides and the back.
Preacherman