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To 7/8 or NOT to 7/8, that is the equastion

I posted three Vector models. I also posted a Sigma 4 model to specs. All with masts attached.

1. 28.6' model is the Vector extended as your suggested, The black line is the Primary model
2. 26.8' the stock Vector and is blue

I should not have added the last two models. Forget the comparisons I added with the S4 length idea for the last two, green and red patterns. Black and blue are the two colored line patterns that apply to your question...as I understand it.



Sigma 4 model is 331" x .75" inches used for the overall radiator length, and 90.5" x .50" inches used for the overall length of the three radials.



NB, I will add the 1" to the "Vector 28.6' with mast" model that is set at 28.6' inches already...the black line in the overlay patterns above. Do you really think one inch will make a difference that matters? I would be surprised if it did. The Vector model also has a 5" inch diameter top hat that is not included in the overall radiator length, but is part of the model.
I just Purchased and Assembled my New Vector 4000 and have the 10k Gamma Match on the Way for it What is the Best Length to run the Gamma at for 27.205 I tried the listed settings but the Ohmage is lower than it should be and the SWR's are Up, i seen somewhere where they suggested moving the Gamma Bar up the Antenna to Increase the Resistance , i may have screwed up the Translation some How What would you suggest i set the Gamma Bar and Rod At?
Im going to shoot for the Taller option!
 
I just Purchased and Assembled my New Vector 4000 and have the 10k Gamma Match on the Way for it What is the Best Length to run the Gamma at for 27.205 I tried the listed settings but the Ohmage is lower than it should be and the SWR's are Up, i seen somewhere where they suggested moving the Gamma Bar up the Antenna to Increase the Resistance , i may have screwed up the Translation some How What would you suggest i set the Gamma Bar and Rod At?
Im going to shoot for the Taller option!
On flat terrain, maximum signal on the horizon will occur, right between 3/4 and 7/8th wave. If you can't get a good match with the aftermarket gamma, try the stock one. Especially if the aftermarket one is shorter. Selling a 10kw gamma match for the Vector is a bit of a gimmick since the connector itself is limited in power, right around the same place as the stock gamma. If you need to increase the power handling, the stock connector is the first thing that must go. Also, if the gamma is the one with red heat shrink tubing on eBay, it doesn't appear to be any larger in diameter than the stock one. The 10kw match Maco sold, use to be 3/4 inch diameter and only handled 10kw PEP. No where near 10kw average. If the tubing is close to stock diameter and only the insulation has been replaced with Teflon, figure on 5kw PEP before bang. The connector will get you, long before this point too.

The stock connector bracket can be drilled and tapped to accept the standard sized, single hole, threaded UHF connector, that is Teflon insulted. I don't recommend just drilling the hole larger and using the connectors nut to hold it in place because, the bracket material is thick enough that you won't have enough threads, to securely tighten the nut. This bracket has been upgraded and is now made from Zamak alloy, which is much stronger than aluminum. Meaning, you'll need a starter tap for this job otherwise, you'll just strip out the threads as you cut them, with a standard finishing tap. You can solder a round, "crimp on" eye connector to the center pin of the new UHF connector and bolt it to your heavy duty gamma match. The eye connector soldered to the top of the UHF connector, is exactly how Avanti made this connection 35 years ago on the original Sigma IV. Apply clear "GE Advanced Silicon 2" caulk over the back of the connector, to prevent water migration.
 
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On flat terrain, maximum signal on the horizon will occur, right between 3/4 and 7/8th wave. If you can't get a good match with the aftermarket gamma, try the stock one. Especially if the aftermarket one is shorter. Selling a 10kw gamma match for the Vector is a bit of a gimmick since the connector itself is limited in power, right around the same place as the stock gamma. If you need to increase the power handling, the stock connector is the first thing that must go. Also, if the gamma is the one with red heat shrink tubing on eBay, it doesn't appear to be any larger in diameter than the stock one. The 10kw match Maco sold, use to be 3/4 inch diameter and only handled 10kw PEP. No where near 10kw average. If the tubing is close to stock diameter and only the insulation has been replaced with Teflon, figure on 5kw PEP before bang. The connector will get you, long before this point too.

The stock connector bracket can be drilled and tapped to accept the standard sized, single hole, threaded UHF connector, that is Teflon insulted. I don't recommend just drilling the hole larger and using the connectors nut to hold it in place because, the bracket material is thick enough that you won't have enough threads, to securely tighten the nut. This bracket has been upgraded and is now made from Zamak alloy, which is much stronger than aluminum. Meaning, you'll need a starter tap for this job otherwise, you'll just strip out the threads as you cut them, with a standard finishing tap. You can solder a round, "crimp on" eye connector to the center pin of the new UHF connector and bolt it to your heavy duty gamma match. The eye connector soldered to the top of the UHF connector, is exactly how Avanti made this connection 35 years ago on the original Sigma IV. Apply clear "GE Advanced Silicon 2" caulk over the back of the connector, to prevent water migration.
I just Assembled it with the Stock one for Now im going to use the 10k replacement later when i get my Swan Mark 1 Fixed! My Main Concern is the Gamma Rod and Bar what should these be set at? Also i have seen where people recommend a Balun but i am running LMR400 so i was thinking about using of using a RG8 Jumper temporary for that purpose.... Im trying to Tune this for the Center of CB Band, Your help is appreciated!
Also i am in a Valley in North Georgia @ 1726' above sea level with a 1800' elevation ridge behind me East and a 2300' elevation hill to the west i am starting out with this antenna lower to the ground 10-15' off the ground but have a 50' Tower to put up it will be on Eventually when i get some things moved around and Help to put it Up!
 
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I just Assembled it with the Stock one for Now im going to use the 10k replacement later when i get my Swan Mark 1 Fixed! My Main Concern is the Gamma Rod and Bar what should these be set at?
The proper setting is the one that shows a 1:1 VSWR. The reactance test on most analyzers is inaccurate enough that you can completely ignore it and just tune for minimum reflected power.
 
The proper setting is the one that shows a 1:1 VSWR. The reactance test on most analyzers is inaccurate enough that you can completely ignore it and just tune for minimum reflected power.

Im trying to tune this with a Nano VNA and im New to these what should i set as the 4 set i just set number 1 to SWR? Currently this Antenna reads lowest @ 2.2SWR lowest SWR i think because of the Gamma the capacitance is over 120. and the resistance is low im thinking i need to move the gamma bar up and the gamma rod out! I just removed several trees that limbs was close and it Helped now im going to put it on a different pole and set the Gamma! it is Now resonating About 27.045 wich is fine and under a 2 by the Nano the ohms are around 40


!
 
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Use whatever shows SWR. Pay less attention to the impedance the device shows and just tune for best SWR.
Indeed that is what i have Always Done but Seek input Thanks for the Input. the gamma is reading high on Capacitance Also i seen in another post it should be Around 55pf its reading 120, I question Everything ... Like to Fine Tune All Setups until its Best, I Designed and Built a High Nickle Stainless Starduster with a Analyser Flat SWR on CB and Wide Banded i Made 3 of them with my Neighbor Professional pipe fitter Welded all of them together! i want to get this Antenna to Flat SWR also just trying to save some time in the setup! I Also Made a J pole out of Aluminum Scrap that worked well about 27' tall , im not used to dealing with this type of Gamma match I know the length of the Antenna is in the Neighborhood but think the Gamma needs some tuning and i have to Make a Balun for it was thinking about 6' jumper of RG8 for now the rest of the Coax is LMR400!
 
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This is my first antenna with this type of Gamma Match so i appreciate Advice! i have it down currently to make and install the Balun and fine tune the Gamma!
 
This is my first antenna with this type of Gamma Match so i appreciate Advice! i have it down currently to make and install the Balun and fine tune the Gamma!

If you're looking for a perfect VSWR, it will take going over both gamma match adjustments several times before you tune out all of the reactance. The length of the bar and the location of the bracket, interact in such a way that adjusting both for lowest setting, will allow you to go back over them again, and find a match that continues to improve until it's flat. Then you go and install it in a different location that works fine, but the match is no longer "perfect", or required to be so. Start by seeking perfection and be satisfied with close.

If it's not at least 15 or 20 feet off the ground during tuning and it's going to be installed higher than that, you're kind of wasting your time because a ground reflection that is too close, will change your impedance when the height is increased.
 
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If you're looking for a perfect VSWR, it will take going over both gamma match adjustments several times before you tune out all of the reactance. The length of the bar and the location of the bracket, interact in such a way that adjusting both for lowest setting, will allow you to go back over them again, and find a match that continues to improve until it's flat. Then you go and install it in a different location that works fine, but the match is no longer "perfect", or required to be so. Start by seeking perfection and be satisfied with close.

If it's not at least 15 or 20 feet off the ground during tuning and it's going to be installed higher than that, you're kind of wasting your time because a ground reflection that is too close, will change your impedance when the height is increased.
Yea im working on the 50' tower i have only one section of it up so far and on a 10' pole Half way up the 10' section of Tower! About 5' overlaped
i Changed to the 10k Gamma today and Shortened the Gamma
bar setting to verify what i need to do is the Opposite and will do so tomorrow! Thanks for the Advice! Its what i was thinking myself after i get it tuned i will add more sections of tower and guide wire! I still have to Make the Balun i know it helps allot with Jpoles from my Previous Antenna i made completely out of Old Antenna parts and Aluminum ! I found with it the Longer i made the antenna the longer i had to make the Gamma but it was the direct connection type!
 
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Nothing i did Helped SWR much i think my LMR400 is Bad from being crushed i have rg213 mil spec on the way to replace it something more durable and i think it will handle plenty of Power!
 
If you're looking for a perfect VSWR, it will take going over both gamma match adjustments several times before you tune out all of the reactance. The length of the bar and the location of the bracket, interact in such a way that adjusting both for lowest setting, will allow you to go back over them again, and find a match that continues to improve until it's flat. Then you go and install it in a different location that works fine, but the match is no longer "perfect", or required to be so. Start by seeking perfection and be satisfied with close.

If it's not at least 15 or 20 feet off the ground during tuning and it's going to be installed higher than that, you're kind of wasting your time because a ground reflection that is too close, will change your impedance when the height is increased.
I know from other Post i need a Balun for this Antenna, What size would you recommend i make with the RG213? i have a 75' Length RG213 on the way and i got a 6' RG213 jumper to make the Balun, Would it be best to Make the Balun from the 75' lengths end @ the antenna or make it with the Jumper and join it with a Barrel connector?
 
IMHO, easiest would be to do a "string of beads" on the 75' RG213. This will give you an effective, easy solution. Not the best and not the cheapest, but easy and it will work.

Buy 50 of these for $34.70 :
https://www.mouser.com/ProductDetai...%2B3O5gg6243vliloM00VjuJZ2kcIpoPSy6mI3hU9Hg==

These are type 28 round ferrite "beads" that will slip over your RG213 coax. Each bead will have ~120 Ohms of impedance @ 27Mhz. Before you attach your connector, slip all 50 of these beads onto the coax, then attach the connector. Have these beads starting within 3" of the antenna side connector, wrap electrical tape around the coax on both ends of the stack so it stays together. Stacked, they will cover about 56.25" of your RG-213 and give you ~6000 Ohms of impedance which is enough to be affective in stopping common mode currents from coming down your shield causing RFI and SWR issues. In my experience the Vector 4000 definitely needs a choke balun.

This is a better performing solution than putting them on your 6' RG-213 jumper and using a barrel connector.

If you are thinking of going ham some day and want to operate on the lower HF ham bands, then a type 31 or 77 material is better suited for making this style choke balun on those lower bands.

Good Luck

73
Dr_DX
 
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IMHO, easiest would be to do a "string of beads" on the 75' RG213. This will give you an effective, easy solution. Not the best and not the cheapest, but easy and it will work.

Buy 50 of these for $34.70 :
https://www.mouser.com/ProductDetail/Laird-Performance-Materials/28B0734-000?qs=/ha2pyFaduiBN%2B3O5gg6243vliloM00VjuJZ2kcIpoPSy6mI3hU9Hg==

These are type 28 round ferrite "beads" that will slip over your RG213 coax. Each bead will have ~120 Ohms of impedance @ 27Mhz. Before you attach your connector, slip all 50 of these beads onto the coax, then attach the connector. Have these beads starting within 3" of the antenna side connector, wrap electrical tape around the coax on both ends of the stack so it stays together. Stacked, they will cover about 56.25" of your RG-213 and give you ~6000 Ohms of impedance which is enough to be affective in stopping common mode currents from coming down your shield causing RFI and SWR issues. In my experience the Vector 4000 definitely needs a choke balun.

This is a better performing solution than putting them on your 6' RG-213 jumper and using a barrel connector.

If you are thinking of going ham some day and want to operate on the lower HF ham bands, then a type 31 or 77 material is better suited for making this style choke balun on those lower bands.

Good Luck

73
Dr_DX
Yea I was trying to just make the Balun with the Coax instead of the ferrites i was going to have 6 10" loops and attach it Below the Antenna! My Coax is Pre Assembled and Sealed and that's the only issue with your suggestion thanks for the input....

Amazon product ASIN B07QHW3DBNthat is my COAX on Amazon.
 

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