ZEROFIVE cOLOSSAL 10KW Antenna

[Ranch55]

Okay, well I have the Colossal 10K up and running.
I was only able to get it tuned to 1.18 VSWR on my RigExpert 55 Zoom analyzer.
This is at the antenna. Coming into the radio room, the VSWR is at 1.26 .....
These are good readings, but I was hoping to get it down below 1.1 like my Penetrator 500 will tune to.
It seems that the receive is as good as the Penetrator with very little rf noise.

 

[JAF0]

Okay, well I have the Colossal 10K up and running.
I was only able to get it tuned to 1.18 VSWR on my RigExpert 55 Zoom analyzer.
This is at the antenna. Coming into the radio room, the VSWR is at 1.26 .....
These are good readings, but I was hoping to get it down below 1.1 like my Penetrator 500 will tune to.
It seems that the receive is as good as the Penetrator with very little rf noise.

If you continue to work with the length & matching network you should be able to tune to 1:1 & X=0 @ 50-52ohms.
If you tend to work mostly ch17 - ch40 I've found 265.5" a good vertical length from match to tip.

Where do you live, what channel/frequency do you frequent & what's your call? I'll listen for you.

 

[Ranch55]

If you continue to work with the length & matching network you should be able to tune to 1:1 & X=0 @ 50-52ohms.
If you tend to work mostly ch17 - ch40 I've found 265.5" a good vertical length from match to tip.

Where do you live, what channel/frequency do you frequent & what's your call? I'll listen for you.

Are you using the ZEROFIVE Colossal 10K 5/8 wave antenna ?
At this time, the total antenna length, from tip to very bottom, is at 22' 5" ........
I did not measure from tip to the hor. radials, or down to the matching capacitor.
I am out on a ranch in southwest Texas.....
Tom, ( ZEROFIVE ANTENNA builder), told me to only work with the matching capacitor adjustment, and to set the length as he has it marked for assembly.

 

[hotrod]

your swr looks fine to me. im more curious what your x= and r =

 

[Ranch55]

FIVE ZERO Colossal 10K 5/8 wave 11 meter antenna .......500khz bandwidth
Rig Expert AA-55 Zoom and MFJ-259C readings match ......
LMR400 UF multi-strand center conductor .......

I set center frequency at 27.345 mhz ......

SWR reading at antenna with 3' lead to analyzer ..... 1.10

Readings below are in radio room coax lead coming in .......

SWR = 1.12 at center frequency 27.345 mhz
Z = 54 ohms
R = 53.9 ohms
X = 6.52 ohms

SWR
- 250 khz = 1.3
+250 khz = 1.3
-500 khz = 1.8
+500 khz = 1.7

 

[Red Bull]

Old thread, but are you still rocking to he colossal 10k?

 

[FredTx63]

I just put a Colossal 10k in the top of an ~80 ft. tall pine tree. It's over 100 ft. high to the tip. I need to have my tree climber go back up in the next week or two to adjust the tuning capacitor at the base of the antenna (I never should have touched it in hindsight, but once on the 10 ft. tall test pole in my yard, I fine-tuned it for channel 20, once 80+ ft in the tree on a 20 ft. mast (only a few ft. of the mast protrudes above the top of the tree) resonance moved to 27.780 or so. Thankfully my tree climber has agreed to go back up and make the adjustments while I watch my analyzer (for no chump change, mind you - and I don't blame him!) I plan to make a post soon outlining my install w/ details, pics, results and impressions of the antenna.

 

[Marconi]

Fred, you may find a lot more going on than a simple adjustment of the capacitor you plan to make up in the pine tree.

What you describe above going on from channel 27.205 to 27.780 mhz on raising over 100'...sounds like feed line radiation out of control and changing the match with the change in feed line length on raising.

I think I've also heard other owner's of this Colossal say that their new antenna can be pre-tuned on request, and if that was so it was also said in the instructions DO NOT adjust the antenna on installation if it does not respond with a good match.

Further more, if you have problems contact the manufacture for further tuning instructions. This is either true or this statement is not true.

 

[Ranch55]

Old thread, but are you still rocking to he colossal 10k?

Yes sir, the Colossal 10K is still up and rocking.......
I am extremely pleased with it.

 

[FredTx63]

Fred, you may find a lot more going than a simple adjustment of the capacitor you plan to make up in the pine tree.

What you describe above going on from channel 27.205 to 27.780 mhz on raising over 100'...sounds like feed line radiation out of control and changing the match with the change in feed line length on raising.

I think I've also heard other owner's of this Colossal say that their new antenna can be pre-tuned on request, and if that was so it was also said in the instructions DO NOT adjust the antenna on installation if it does not respond with a good match.

Further more, if you have problems contact the the manufacture for further tuning instructions. This is either true or this statement is not true.

The owner/builder says not to make any adjustments to the primary element or radial lengths (assemble using his sharpie marks and leave the lengths alone) to affect tuning, only to make minor adjustments to the sliding tuning cap at the bottom. Antenna resonance was a bit below CB channel 1 on the 10 ft. test mast with my analyzer at the end of my 150 ft. of LMR-600. A few adjustments to the cap helped me move resonance to mid-CB band with an SWR of about 1.06. Then the antenna was mounted to a 20 ft. mast and hoisted up into and bolted to the pine tree. Ground radials re-installed once the antenna mast was secured to the tree.

I guess it's possible some component of either matching network could have been bumped when being hoisted up and into the tree or when the climber was securing it. I did supervise the entire installation though and didn't see anything like this happen. I've even flown my drone up and checked everything out and nothing looks bent or anything.

I really have no reason to believe a few minor adjustments to the tuning capacitor wouldn't bring resonance back down to 27.205 from 27.780 or so where it is now. Why it changed so much from test mast to top of tree I'm not certain of. Maybe it was too close to the ground originally and had I left well enough alone it would have been closer to resonant at channel 20 once it got up in the tree? I believe the builder tunes all of the CB Colossal antennas for channel 20 unless a different frequency is requested. It seems the tuning I now need to make is to "undo" the tuning I did with it 10 ft. off the ground. A number of things changed from test to final installation: 10 ft vs 20 ft mast, the addition of 100+ ft. of #6 braided copper ground wire from the bottom mast bolt on the antenna to ground rod below, etc.



In the second picture you can see the tree climber had still not removed the old mast from the Imax 2000 I had in the tree previously, that was removed while he was up there.

 

[hotrod]

before ya make any adjustments id call and talk withthe builder ask him why it changed so much

 

[RParz]

The owner/builder says not to make any adjustments to the primary element or radial lengths (assemble using his sharpie marks and leave the lengths alone) to affect tuning, only to make minor adjustments to the sliding tuning cap at the bottom. Antenna resonance was a bit below CB channel 1 on the 10 ft. test mast with my analyzer at the end of my 150 ft. of LMR-600. A few adjustments to the cap helped me move resonance to mid-CB band with an SWR of about 1.06. Then the antenna was mounted to a 20 ft. mast and hoisted up into and bolted to the pine tree. Ground radials re-installed once the antenna mast was secured to the tree.

I guess it's possible some component of either matching network could have been bumped when being hoisted up and into the tree or when the climber was securing it. I did supervise the entire installation though and didn't see anything like this happen. I've even flown my drone up and checked everything out and nothing looks bent or anything.

I really have no reason to believe a few minor adjustments to the tuning capacitor wouldn't bring resonance back down to 27.205 from 27.780 or so where it is now. Why it changed so much from test mast to top of tree I'm not certain of. Maybe it was too close to the ground originally and had I left well enough alone it would have been closer to resonant at channel 20 once it got up in the tree? I believe the builder tunes all of the CB Colossal antennas for channel 20 unless a different frequency is requested. It seems the tuning I now need to make is to "undo" the tuning I did with it 10 ft. off the ground. A number of things changed from test to final installation: 10 ft vs 20 ft mast, the addition of 100+ ft. of #6 braided copper ground wire from the bottom mast bolt on the antenna to ground rod below, etc.

View attachment 41483 View attachment 41484

In the second picture you can see the tree climber had still not removed the old mast from the Imax 2000 I had in the tree previously, that was removed while he was up there.

What ever happened with this? From what I've read 5/8 ground plane antennas are designed with mast grounding in mind. A pine tree, while quite tall, probably doesn't offer the counterpoise that is assumed. Not that you can't do what you're trying to do, you probably just need to make some tree-specific accommodations.