Predator 10k issues

[The DB]

Wondering if I should think about investing in an analyzer? At this point that would be the only tool to help me get past this right?

Most new people who use antenna analyzers use them wrong. To benefit from such a device you need to get over the SWR tuning mindset. If you get one with the sole purpose of getting SWR lower you are not getting the real benefit that the analyzer provides, and ending up not getting any more benefit out of it than an SWR meter can provide. Seriously though, to get the most out of an antenna setup, SWR really doesn't tell you anything aside from weather or not it is safe to transmit.

As it is now with a permanent mount you can lengthen and shorten the antenna, and with the addition of changing the lower shaft length that is the limit of what you can do. If you are not looking to tune for resonance, and instead focused on low SWR the analyzer is a waste of money for you. Your amplifier will require this anyway...

If you can't get that SWR down, drive the amplifier with less power. This would make the use-able safe SWR range for the amplifier larger, and actually, people receiving would not notice the difference anyway. It takes far more of a change in power for someone to notice a difference than most people think. If you cut your output power in half, that is 1/4 an s-unit on a properly calibrated s-meter (good luck finding one of those in the "real world", especially on the CB side of things...)


The DB

[BIGHOG]

Wondering if I should think about investing in an analyzer? At this point that would be the only tool to help me get past this right?

Most new people who use antenna analyzers use them wrong. To benefit from such a device you need to get over the SWR tuning mindset. If you get one with the sole purpose of getting SWR lower you are not getting the real benefit that the analyzer provides, and ending up not getting any more benefit out of it than an SWR meter can provide. Seriously though, to get the most out of an antenna setup, SWR really doesn't tell you anything aside from weather or not it is safe to transmit.

As it is now with a permanent mount you can lengthen and shorten the antenna, and with the addition of changing the lower shaft length that is the limit of what you can do. If you are not looking to tune for resonance, and instead focused on low SWR the analyzer is a waste of money for you. Your amplifier will require this anyway...

If you can't get that SWR down, drive the amplifier with less power. This would make the use-able safe SWR range for the amplifier larger, and actually, people receiving would not notice the difference anyway. It takes far more of a change in power for someone to notice a difference than most people think. If you cut your output power in half, that is 1/4 an s-unit on a properly calibrated s-meter (good luck finding one of those in the "real world", especially on the CB side of things...)


The DB

I'm not familiar with the operating function of an analyzer in tuning an antenna. Is it better to use an analyzer or swr meter? Trying to learn more about it. Yes, I want to maximize my antenna system to its full capacity. Turning the amp back does not really seam like the solution for me. Though I completely understand why you recommended that. This is a from scratch install using all quality components and materials. I am a perfectionist at heart and enjoy the tinkering and challenge part of the hobby, not just communications. If I need to purchase a new tool (analyzer) I am willing to do so, depending on a reasonable cost of course. Tools are never a waste of money IMO. I just want to do this the correct way at 110%

[jessejamesdallas]

Something you could try that may help...If you have access to a magnet mount for the 10K, (something like a tri-mag mount) then you could move the antenna around on the roof till you find the "sweet-spot" and see if it will tune any better.

I know you've already drilled da hole, but you will probably find you drilled in the wrong spot... I've found this to be true a number of times dealing with Predator 10K's.

[MDYoungblood]

For years I used and compared several different SWR/Watt meter when making adjustment to antennas, then I purchased a MFJ-259B Analyzer, it changed my entire way of making antenna adjustments. I knew about capacitance, resistance, resonance, but never really used that before the analyzer. After reading the manual (several times) and playing with homemade antennas I have using it down pat. An SWR meter will get you close but an analyzer will tell you so much more plus it saves wear and tear on your radio equipment. If you have the means I would get one, I bought mine for personal use but it has made it's way around adjusting my close friend's antenna systems. If you find one used, they can be found for a good price, it may need to be calibrated, manuals can be gotten online.

Now the other question, if the SWR from 1 to 40 is a flat 1.5:1 then I don't think longer or shorter is going to help. You have the idea, get the SWR on ch 19 the lowest you can get it then balance out channels 1 and 40, you could even go a band up and down to see more curve in the SWR.

What DB is saying is there is no need to run the amp full tilt, the receiving end is never going to see the difference. Running the amp on a lesser wattage setting will increase it's longevity and create less heat with that slightly higher SWR.

3's

Greg

[The DB]

I'm not familiar with the operating function of an analyzer in tuning an antenna. Is it better to use an analyzer or swr meter?

If you are tuning a raw antenna and don't have that strict SWR limitations, proper use of an antenna analyzer will almost always give you better performance than just an SWR meter. However, if you are in a situation where a low SWR is the primary requirement, and you are limited in the adjustments of the antenna (can't move it around and such and can only really adjust things like length) an SWR meter will do just as much as that fancy antenna analyzer.

Trying to learn more about it. Yes, I want to maximize my antenna system to its full capacity. Turning the amp back does not really seam like the solution for me. Though I completely understand why you recommended that.

In your case, you have the choice of one or the other, and you might not even have one of those choices available. It is also an option to get you on the air now. You can spend a week or two gathering info and work to fix it later. This would also give you the experience of how much a difference such a change in power actually makes.

This is a from scratch install using all quality components and materials. I am a perfectionist at heart and enjoy the tinkering and challenge part of the hobby, not just communications. If I need to purchase a new tool (analyzer) I am willing to do so, depending on a reasonable cost of course. Tools are never a waste of money IMO. I just want to do this the correct way at 110%

Sometimes working with antennas is a science, and others it is an art. Perfection with antennas (especially mobile antennas) is a rare thing, although always something to shoot for. In a mobile environment, for example, you have at least two big strikes against you before you even get started. Your vehicle, for example, is not really a great ground plane to begin with, and this includes large SUV's, although smaller cars are even worse. There is also the fact that the antenna is mounted very close (as far as the antenna is concerned) to the earth, height really is might after all. Antenna lengths used are often a compromise as well, while your antenna is long enough, many people are limited to antennas of five feet in length or shorter, which is a third big strike. Even with all these compromises, antennas still often work, how well depends on how well the installer dealt with said compromises.

It is all a learning process, there are those who have spent decades learning this stuff, and are still learning today. Don't be afraid to try things, and if something unexpected happens ask about it, there is always a reason.

Bonding was mentioned in your first post, but I don't see where it has or has not been done. If you haven't yet, I would do that before doing anything else. If you need help, search online, there is plenty of information on it out there. If you still need help ask. Bonding, in and of itself, will often lower SWR, although depending on your setup is can raise the SWR as well. In either case, the antenna system will perform better with it done than without it.

Something you could try that may help...If you have access to a magnet mount for the 10K, (something like a tri-mag mount) then you could move the antenna around on the roof till you find the "sweet-spot" and see if it will tune any better.

I know you've already drilled da hole, but you will probably find you drilled in the wrong spot... I've found this to be true a number of times dealing with Predator 10K's.

As he has already drilled a hole I was hesitant to suggest this. It will show him how SWR can change simply by moving an antenna around a vehicle. The thing is things like the antenna system's radiation pattern will also change, and not always for the better, and it is difficult to see those changes. It doesn't hurt to do though. If something like this is done be careful with the tri-mag mount, you want something between it and your paint or your paint will get scratched up as you move it around. Also, don't use that amp through said mount, the capacitive coupling generally cannot handle that kind of power, and you will end up with burn marks on said paint. In most cases a magnet mount can handle about 100 watts safely, sometimes a little more.

One other thing to try, check the antennas SWR with the amp on and off. If it is higher with the amp on, then the amp is generally not putting out a clean signal, at which point the amplifiers power is not only not on the channel, but possibly not even in the bandwidth of the antenna in question. Such transmitted power is doing you absolutely no good, and possibly causing other people elsewhere in the spectrum interference problems.


The DB

[BIGHOG]

Such good info gentleman.! No, nothing on the truck is bonded yet. I actually took a Wilson 1000 mag mount and moved it around to come up with the location to drill. my old truck was bonded beyond belief and it did help both with handling power and with swr. The new setup will be fully bonded as well. That might get me to where I want to be. Hopefully, seeing how I already drilled. Lol. I will get some pics up tonight as soon as I can figure out how to shrink the file size.

[jessejamesdallas]

Such good info gentleman.! No, nothing on the truck is bonded yet. I actually took a Wilson 1000 mag mount and moved it around to come up with the location to drill. my old truck was bonded beyond belief and it did help both with handling power and with swr. The new setup will be fully bonded as well. That might get me to where I want to be. Hopefully, seeing how I already drilled. Lol. I will get some pics up tonight as soon as I can figure out how to shrink the file size.

Problem using the Wilson to find the sweet-spot, is it's a different antenna than the Predator because the coil is right on bottom vs. the Predators coil is 17" off the roof, so they can tune differently... Best to use the antenna that your planing on using permanently to find the sweet-spot...Then get drill happy!

Case in point...On my Suburban, my Predator 10K tuned the best about 6" from the back...In the middle of the roof or up closer to the front, I couldn't get it to tune worth a crap...However, I had a Wilson 5000 Mag Mount antenna that tuned just fine close to the front...(the Wilson also tuned ok near the back)

[BIGHOG]

Such good info gentleman.! No, nothing on the truck is bonded yet. I actually took a Wilson 1000 mag mount and moved it around to come up with the location to drill. my old truck was bonded beyond belief and it did help both with handling power and with swr. The new setup will be fully bonded as well. That might get me to where I want to be. Hopefully, seeing how I already drilled. Lol. I will get some pics up tonight as soon as I can figure out how to shrink the file size.

Problem using the Wilson to find the sweet-spot, is it's a different antenna than the Predator because the coil is right on bottom vs. the Predators coil is 17" off the roof, so they can tune differently... Best to use the antenna that your planing on using permanently to find the sweet-spot...Then get drill happy!

Case in point...On my Suburban, my Predator 10K tuned the best about 6" from the back...In the middle of the roof or up closer to the front, I couldn't get it to tune worth a crap...However, I had a Wilson 5000 Mag Mount antenna that tuned just fine close to the front...(the Wilson also tuned ok near the back)

SO am I just screwed on this deal? The 108 tunes flat but that's 9' on top of a dually! Not gonna work..... Just start bonding the crap out of it and hope the swr comes down? And maybe try a 22'' base? I hate just throwing money at parts to try.....

[Deleted User 14541]

You can try adding some bonding straps between the cab and bed but if you don't see any change in SWR I'd move on to something else. A longer shaft might do the trick or another antenna might be your best bet. Either choice is going to be a crap shoot. If you just have to make that one work adding some inductance or capacitance at the feed point might be the solution...basically building a matcher.

The 22" shaft really puts the coil too high for my taste. It hits everything as it is and the more shaft the less flex. A friend of mine had a similar issue with a 1 ton van. We thought it would be a walk in the park with a larger roof than a suburban. The short shaft wilson would not tune on 11 meters, a 102 was a perfect match in the upper portion of 10 meters. He ended up using 2 antennas anyway so his solution was much different.

[BIGHOG]

You can try adding some bonding straps between the cab and bed but if you don't see any change in SWR I'd move on to something else. A longer shaft might do the trick or another antenna might be your best bet. Either choice is going to be a crap shoot. If you just have to make that one work adding some inductance or capacitance at the feed point might be the solution...basically building a matcher.

The 22" shaft really puts the coil too high for my taste. It hits everything as it is and the more shaft the less flex. A friend of mine had a similar issue with a 1 ton van. We thought it would be a walk in the park with a larger roof than a suburban. The short shaft wilson would not tune on 11 meters, a 102 was a perfect match in the upper portion of 10 meters. He ended up using 2 antennas anyway so his solution was much different.

I thought this dually would be a breeze as well because of its size. The first antenna I checked was the 108. When it came in flat with zero bonding I was stoked . The I screwed the 10k on and had my bubble popped fast So how do I know if I need inductance or capacitance? Is that where the analyzer comes in? Should I post this in the mobile setup section as well?

[MDYoungblood]

Not really, you are obligated to the location of the puck now just need to get the right configuration of antenna that will work. Since the 108" (check the actual length, could be 102") whip is tuning out so will the P10K. Never did ask if there was a cap on the bed, that too could be a factor.
Another thought is the design of the antenna may be exhibiting some common mode current causing a misreading. Coax location and positioning can also cause this too. I would get started on the bonding like you said and take some readings as you go.

Here is a good site to read, [Please login or register to view this link] , It's a ham site but everything there can be used in CB too.

3's

Greg

[Deleted User 14541]

You can try adding some bonding straps between the cab and bed but if you don't see any change in SWR I'd move on to something else. A longer shaft might do the trick or another antenna might be your best bet. Either choice is going to be a crap shoot. If you just have to make that one work adding some inductance or capacitance at the feed point might be the solution...basically building a matcher.

The 22" shaft really puts the coil too high for my taste. It hits everything as it is and the more shaft the less flex. A friend of mine had a similar issue with a 1 ton van. We thought it would be a walk in the park with a larger roof than a suburban. The short shaft wilson would not tune on 11 meters, a 102 was a perfect match in the upper portion of 10 meters. He ended up using 2 antennas anyway so his solution was much different.

I thought this dually would be a breeze as well because of its size. The first antenna I checked was the 108. When it came in flat with zero bonding I was stoked . The I screwed the 10k on and had my bubble popped fast So how do I know if I need inductance or capacitance? Is that where the analyzer comes in? Should I post this in the mobile setup section as well?

Yeah you'd really need an analyzer to work out something like that out without a lot of guess work. Honestly I'd try a longer shaft first.

Do you have anything you could use to temporarily extend the shaft you have now? Maybe a piece of all thread and some nuts or some spare antenna parts, some nuts spot welded to a piece of pipe. You could even hose clamp something together. Not sure what your situation is or what kind of resources you might have laying around.

[BIGHOG]

You can try adding some bonding straps between the cab and bed but if you don't see any change in SWR I'd move on to something else. A longer shaft might do the trick or another antenna might be your best bet. Either choice is going to be a crap shoot. If you just have to make that one work adding some inductance or capacitance at the feed point might be the solution...basically building a matcher.

The 22" shaft really puts the coil too high for my taste. It hits everything as it is and the more shaft the less flex. A friend of mine had a similar issue with a 1 ton van. We thought it would be a walk in the park with a larger roof than a suburban. The short shaft wilson would not tune on 11 meters, a 102 was a perfect match in the upper portion of 10 meters. He ended up using 2 antennas anyway so his solution was much different.

I thought this dually would be a breeze as well because of its size. The first antenna I checked was the 108. When it came in flat with zero bonding I was stoked . The I screwed the 10k on and had my bubble popped fast So how do I know if I need inductance or capacitance? Is that where the analyzer comes in? Should I post this in the mobile setup section as well?

Yeah you'd really need an analyzer to work out something like that out without a lot of guess work. Honestly I'd try a longer shaft first.

Do you have anything you could use to temporarily extend the shaft you have now? Maybe a piece of all thread and some nuts or some spare antenna parts, some nuts spot welded to a piece of pipe. You could even hose clamp something together. Not sure what your situation is or what kind of resources you might have laying around.

Yes, I can come up with a temporary shaft to try out to see the result. Might look into an analyzer as well, I know I could have used one a few times in the past and could use one now. Usually if you need a tool three times.................

[drdx]

I'm late t this topic, but do you have a pic of the underside connection? I've had issue there before where I had a bit of I shielded center conductor exposed, effectively part of the antenna once it leaves the shield, and I redid it and resolved some readings. Coincidence? Who knows but it behaved after that. Have you tried a tuned wire counterpoise anywhere or a choke, just to see where things go reading wise?

-drdx

[BIGHOG]

So this afternoon I got everything fired up. The install is complete. I am now referencing my Ameritron AWM-35 as well as the RS swr meter. The Ameritron has the remote box after the amp and sends signal via CAT 5 cable to the display on the dash. The rs meter still reads a flat 1.5 across the band. The Ameritron is giving me just a hair over 1.1. Difference caused by location of of sampling? I just said screw it and start powering up the Fatboy 2x8. I am seeing 750w RMS (1250pep) with 18w of reflect all from a 2.5 w DK. I'm happy with that as a starting point seeing how no bonding is in place yet. Made multiple contacts on skip as well as local this evening and all reports were excellent. Not seeing excessive draw from the charging system IMO and everything seems to be running at an acceptable temperature. I'm now wondering which meter to believe... As soon as I figure out how to make pictures smaller I will post up some pics of the install. Also....... On watching the Ameritron during modulation the reflect actually decreases when modulating but still have forward swing.... Normal? Cant say that I ever remember seeing that before. Opinions or concerns on these numbers or information, at least for the initial power up? This may have gone beyond the "Predator 10k issues" post in the antenna help section... Sorry

[drdx]

Nice. I run that same meter and love it for a mobile. Great numbers too.

-drdx

(edited by MDY, removed double post)

[jessejamesdallas]

drdx loves that meter in his mobile!

[BIGHOG]

Who knows how to take the pics on my Android phone and make the file size smaller so I can post up?

[Deleted User 14541]

I used one if those meters on the base for years. The amps are in the garage and the radios are in a spare bedroom so a remote head is a must. It didn't like a 2kw carrier when I tune up so I finally retired it and bought a bird.

The reason you are getting different readings is because the meters are at different points. There may be some common mode on the feedline causing that or some other minor issue. Did you use the ferrite or a choke at the feed point?

What I would do is install the watt meter sensor with a double male pl259 directly to the output of the amplifier. If you have to use coax for any reason keep it as short as possible. If you have low swr at that point the amplifier is safe.

The reflect dropping with modulation is nothing to worry about. The numbers you posted sound good to me. 750 with 18 reflected is just a hair over 1.3 swr. What kind of reflect do you see with a dead carrier? You said 18 watts reflect with 2.5 dk. I'm assuming the 2.5 is deadkey into the amp. How much reflect do you have and how much is the amplifier dead keying?

[drdx]

I run a low pass filter after the radio and before the amps. Depending on how clean the radio is, it can make a real difference in the readings. Garbage in, more garbage out and I figure I may as well nip it at the bud before the 54mhz harmonics hit the antenna and my reflect rears its ugly head. Avoiding export radios and using stock radios is my way of life now.

I have the palstar and it is much nicer on fit and finish but the meter box doesn't lend itself well to mobile use. The only issue I've had on the mfj was keeping the cat 5 connection at the sensor end nice and clean.

-drdx

[Deleted User 14541]

I run a low pass filter after the radio and before the amps. Depending on how clean the radio is, it can make a real difference in the readings. Garbage in, more garbage out and I figure I may as well nip it at the bud before the 54mhz harmonics hit the antenna and my reflect rears its ugly head. Avoiding export radios and using stock radios is my way of life now.

I have the palstar and it is much nicer on fit and finish but the meter box doesn't lend itself well to mobile use. The only issue I've had on the mfj was keeping the cat 5 connection at the sensor end nice and clean.

-drdx

X2 on the LPF and avoiding the super trucker radios.

I use the palstar 2000am mobile, it's been a good meter. After re drilling the mounting bracket it fastens to the bottom of my radio using the speaker mounting screws. To prevent scratching I put few layers of tape on the bracket between it and the radio case.

I'm afraid the quality on the ameritron meters slipped. My first awm 35 that I bought around 2009 was a good one. I did have some issues with the light flickering with high power but some ferrite on the cat 5 cable solved that. I broke that meter when I took my station apart to build a new desk this year, so I bought another one. At 2kw it flickered and the readings were so erratic I couldn't tune the amp. It actually stopped working for a few minutes and after that the readings seemed to be a little off. It was used outside it's rating so I guess I can't blame the meter.

[BIGHOG]

I used one if those meters on the base for years. The amps are in the garage and the radios are in a spare bedroom so a remote head is a must. It didn't like a 2kw carrier when I tune up so I finally retired it and bought a bird.

The reason you are getting different readings is because the meters are at different points. There may be some common mode on the feedline causing that or some other minor issue. Did you use the ferrite or a choke at the feed point?

What I would do is install the watt meter sensor with a double male pl259 directly to the output of the amplifier. If you have to use coax for any reason keep it as short as possible. If you have low swr at that point the amplifier is safe.

The reflect dropping with modulation is nothing to worry about. The numbers you posted sound good to me. 750 with 18 reflected is just a hair over 1.3 swr. What kind of reflect do you see with a dead carrier? You said 18 watts reflect with 2.5 dk. I'm assuming the 2.5 is deadkey into the amp. How much reflect do you have and how much is the amplifier dead keying?

No ferrite chokes at the feedpoint. Yes, the dk is into the amp.
I had some of those numbers mixed up switching between meters and RMS and PEP. With the Ameritron meter between the amp and the antenna I'm giving the amp 2.5w from the radio. Which is giving me a carrier of 500w RMS forward , 12w RMS reflected. When modulating I'm getting 750w RMS forward, 3w RMS reflected.

I'm thinking about pulling the trigger on a MFJ-259C. How would I got about building a matcher to make the 10K resonant? I have been doing lots of research on tuning and it makes sense to me know why resonance is so important. It seems like there could possibly be a lot left on the table performance wise if the antenna is not resonant even though the SWR looks acceptable. Is this a correct statement?

[Deleted User 14541]

A matching device doesn't make the antenna resonant. It just gives the transmitter a 50 ohm load to fire into. A good tuner will give you a perfect swr with a coat hanger antenna but it won't transmit very well. An example of a matching device would be using a coil of wire (inductor) in series with the center conductor connection and fine tuning it with a capacitor from center conductor to ground. One or the other may not be needed and the configuration will be different for different situations.

There's no simple answer other than buy some books and experiment. As close as you are there is absolutely nothing to be gained from doing that, you might even make the system less efficient even though you get a lower swr...a good friend of mine calls that meter bating. When I mentioned the matching network I wasn't completely serious. Most guys would have laughed at me and tried another antenna. You are still just a hair over 1.3 so enjoy it.

At 1200 pep you aren't abusing that amplifier so I really wouldn't worry the swr but I would run the carrier at around 300 watts. Not because of your antenna system but if you're running 1200 pep you don't have enough headroom for a fully modulated 500 watt carrier. It will also give those $65 transistors some breathing room. If you need a little extra pep in your step turn it back up enough to get the job done then back it off. It never hurts to have a reserve.

[BIGHOG]

A matching device doesn't make the antenna resonant. It just gives the transmitter a 50 ohm load to fire into. A good tuner will give you a perfect swr with a coat hanger antenna but it won't transmit very well. An example of a matching device would be using a coil of wire (inductor) in series with the center conductor connection and fine tuning it with a capacitor from center conductor to ground. One or the other may not be needed and the configuration will be different for different situations.

There's no simple answer other than buy some books and experiment. As close as you are there is absolutely nothing to be gained from doing that, you might even make the system less efficient even though you get a lower swr...a good friend of mine calls that meter bating. When I mentioned the matching network I wasn't completely serious. Most guys would have laughed at me and tried another antenna. You are still just a hair over 1.3 so enjoy it.

At 1200 pep you aren't abusing that amplifier so I really wouldn't worry the swr but I would run the carrier at around 300 watts. Not because of your antenna system but if you're running 1200 pep you don't have enough headroom for a fully modulated 500 watt carrier. It will also give those $65 transistors some breathing room. If you need a little extra pep in your step turn it back up enough to get the job done then back it off. It never hurts to have a reserve.

"Most guys would have laughed and tried another antenna" LOL. I saw your comment as a challenge and something new to learn and tinker with!!!!

[Deleted User 14541]

A matching device doesn't make the antenna resonant. It just gives the transmitter a 50 ohm load to fire into. A good tuner will give you a perfect swr with a coat hanger antenna but it won't transmit very well. An example of a matching device would be using a coil of wire (inductor) in series with the center conductor connection and fine tuning it with a capacitor from center conductor to ground. One or the other may not be needed and the configuration will be different for different situations.

There's no simple answer other than buy some books and experiment. As close as you are there is absolutely nothing to be gained from doing that, you might even make the system less efficient even though you get a lower swr...a good friend of mine calls that meter bating. When I mentioned the matching network I wasn't completely serious. Most guys would have laughed at me and tried another antenna. You are still just a hair over 1.3 so enjoy it.

At 1200 pep you aren't abusing that amplifier so I really wouldn't worry the swr but I would run the carrier at around 300 watts. Not because of your antenna system but if you're running 1200 pep you don't have enough headroom for a fully modulated 500 watt carrier. It will also give those $65 transistors some breathing room. If you need a little extra pep in your step turn it back up enough to get the job done then back it off. It never hurts to have a reserve.

"Most guys would have laughed and tried another antenna" LOL. I saw your comment as a challenge and something new to learn and tinker with!!!!

That's good. People that like a challenge seem to go further with this hobby.