Yup, the gama match has been around for decades and unlike the sweep tube and 44 in the desert will not be going away anytime soon.
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Avanti Sigma4: An alternative view point
- Thread starter bob85
- Start date
Yes it is the same person, he keeps getting banned, and creating a new user name to get back on and as soon as we see it he gets banned again.
If he had something to contribute to the forum in the way of positive input maybe there could be a way to work something out, but it seems as if this individual has an agenda that serves only his own line of reasoning.
If he comes back again ( and I have no doubt he will ) try to ignore the comments and let one of us know and he will just get banned again.
When I have more time I will go through the threads and clean up any nonsense that has been posted.
We try to let everyone have there say about equipment and radio related topics here on the forum, but when it turns out like this it is bad for everyone.
This Topic about the avanti sigma 4/ Vector 4000/LW150 style antennas has been very informative and thought inspiring, thanks to all that have contributed to it.
Thank You.
73
Jeff
"GAMMAS ARE LOSSEY . THATS WHY THEY CATCH FIRE "
i see you did not graduate in physics or material sciences
"PLUS NO DC GROUND"
or basic electrical principles, there is little wonder you cannot see past a simple j-pole,
"THEY ARE STRUCTURALLY INFERIOR TO AN ANTRON"
this is true,
"IF YOU LIKE THEM YOU HAVEN'T HAD A 10-K"
yes i do on both counts,
the i10k is a great 5/8wave, one of only two available today that will survive for years in our weather, the vector will not stand even moderate weather, i don't like the vector construction quality but i like the superior performance,
"ASK ABOUT THERE 30 DAY UNCONDITIONAL MONEY BACK GUARANTEE"
funny, people don't talk about that but they do talk about your lack of communication and long delivery times,
"OH THAT'S US SORRY YOU WON'T GET THAT FROM ANYONE ELSE BUT US"
thats true, you can usually pay for and receive other brand antennas within 3-5 days,
"IF ANYTHING IS WORTH DOING IT'S WORTH OVER DOING"
not if you are cooking dinner,
"I DON'T GET IT"
that does not surprise me at all,
"PEOPLE WILL SPEND MONEY ON AN AMP BUT NOT A GOOD ANTENNA"
people that buy / build large amplifiers usually don't use onmidirectional antennas, omnis and big amps are for assholes that get a kick out of annoying locals, real dxers use beams,
"I GUESS YOU ALL HAVE A 10 AMP SUPPLY AND A 2 PILL"
thats very presumtuous and unprofessional of you and typically incorrect,
"THAT JUNK WON'T EVEN SUPPORT A 3CX1500A7"
true again, the stock gamma is ok to 1200w fm, higher power requires a high watt rated gamma,
"MY FIRST [LITTLE] METAL CERAMIC TUBE LIT THAT GAMMA JUNK ON FIRE"
a smart guy would not use high power on a stock gamma that is rated at 1000w cw by the manufacturer,
"THAT'S OK , IF YOU DON'T NEED AN INTERCEPTOR 10K DON'T BUY ONE . MORE DUCKS FOR ME TO MAUL"
could you translate this into terminology used by professionals, i tried bablefish but had no luck, bablefish translates various languages but hillbilly to english is not in the list,.
"All constructed of 6063 t8 alloy and commercial grade components"
the i10k does indeed use quality components,
sirios are "Made of aluminium alloy 6063 T-832" the low wind survival comes from using .049" wall tube not some fictional low grade alloy, the strength of the i10k comes from the fast stepped taper design not any special high grade alloy,
6063 was originally created for use in furniture as a cheap alternative to aircraft grade alloys, it became popular with antenna manufacturers because it is significantly less expensive yet strong enough for most antenna applications,
the higher quality.058" wall 6061-t6 aircraft grade material used by avanti has become too expensive for all but a handfull of antenna manufacturers, it is still used in the aircraft/microlite industry where your life depends on it,
"you all speak snake oil"
your failure to comprehend anything more complex than a simple albeit well constructed groundplane does not infere we talk snakeoil anymore than the smell you create around here mean you talk bullshit,
we are not trying to sell anybody anything
i see you did not graduate in physics or material sciences
"PLUS NO DC GROUND"
or basic electrical principles, there is little wonder you cannot see past a simple j-pole,
"THEY ARE STRUCTURALLY INFERIOR TO AN ANTRON"
this is true,
"IF YOU LIKE THEM YOU HAVEN'T HAD A 10-K"
yes i do on both counts,
the i10k is a great 5/8wave, one of only two available today that will survive for years in our weather, the vector will not stand even moderate weather, i don't like the vector construction quality but i like the superior performance,
"ASK ABOUT THERE 30 DAY UNCONDITIONAL MONEY BACK GUARANTEE"
funny, people don't talk about that but they do talk about your lack of communication and long delivery times,
"OH THAT'S US SORRY YOU WON'T GET THAT FROM ANYONE ELSE BUT US"
thats true, you can usually pay for and receive other brand antennas within 3-5 days,
"IF ANYTHING IS WORTH DOING IT'S WORTH OVER DOING"
not if you are cooking dinner,
"I DON'T GET IT"
that does not surprise me at all,
"PEOPLE WILL SPEND MONEY ON AN AMP BUT NOT A GOOD ANTENNA"
people that buy / build large amplifiers usually don't use onmidirectional antennas, omnis and big amps are for assholes that get a kick out of annoying locals, real dxers use beams,
"I GUESS YOU ALL HAVE A 10 AMP SUPPLY AND A 2 PILL"
thats very presumtuous and unprofessional of you and typically incorrect,
"THAT JUNK WON'T EVEN SUPPORT A 3CX1500A7"
true again, the stock gamma is ok to 1200w fm, higher power requires a high watt rated gamma,
"MY FIRST [LITTLE] METAL CERAMIC TUBE LIT THAT GAMMA JUNK ON FIRE"
a smart guy would not use high power on a stock gamma that is rated at 1000w cw by the manufacturer,
"THAT'S OK , IF YOU DON'T NEED AN INTERCEPTOR 10K DON'T BUY ONE . MORE DUCKS FOR ME TO MAUL"
could you translate this into terminology used by professionals, i tried bablefish but had no luck, bablefish translates various languages but hillbilly to english is not in the list,.
"All constructed of 6063 t8 alloy and commercial grade components"
the i10k does indeed use quality components,
sirios are "Made of aluminium alloy 6063 T-832" the low wind survival comes from using .049" wall tube not some fictional low grade alloy, the strength of the i10k comes from the fast stepped taper design not any special high grade alloy,
6063 was originally created for use in furniture as a cheap alternative to aircraft grade alloys, it became popular with antenna manufacturers because it is significantly less expensive yet strong enough for most antenna applications,
the higher quality.058" wall 6061-t6 aircraft grade material used by avanti has become too expensive for all but a handfull of antenna manufacturers, it is still used in the aircraft/microlite industry where your life depends on it,
"you all speak snake oil"
your failure to comprehend anything more complex than a simple albeit well constructed groundplane does not infere we talk snakeoil anymore than the smell you create around here mean you talk bullshit,
we are not trying to sell anybody anything
Ya know, I was just thinking (no, REALLY!) - What about using an I-10K and adding some bent tubing to the bottom radial mounts, bent up to become upward radials like the SigmaIV, add some basic aluminum tubing for the ring, then add a few feet of maybe Wilson 1000 whip or equivalent to fab your own high-longevity SigmaIV-type omni aerial?
do any of you guys even talk on the bowl.If so what are your numbers.I dont see any beams up next to the omni antennas in your pictures.
Ya know, I was just thinking (no, REALLY!) - What about using an I-10K and adding some bent tubing to the bottom radial mounts, bent up to become upward radials like the SigmaIV, add some basic aluminum tubing for the ring, then add a few feet of maybe Wilson 1000 whip or equivalent to fab your own high-longevity SigmaIV-type omni aerial?
Based on my experience with homebrewing one of these, I believe the position of the radials along the length of the main aerial is critical to the performance of the antenna. Making one as you describe is virtually what I did, and it performed poorly even compared to my 1/2^ monopole closed-sleeve I also have up at a lower elevation. It is possible to get a good SWR, but it is not working well.
When I have more time, and the weather cools some, I hope to rework the antenna and see what happens.
Oh no, I intended it to be that way, though I truly believe in comparisons which utilize the same mast / coax / radio, etc, I wanted to try out two antennas simultaneously to my friend 80 miles away, who's at 2200' ASL.
They are right at ½ wave separation which is a null, so each sees the other as basically invisible.
Only at directions directly perpendicular to the plane running across both antennas can I feel it is a somewhat fair comparison.
- Also, I ended up using identical lengths of the sme coax from the same piece I cut in half.
Maybe not a perfect scenario, but interestingly revealing and closer than a hand grenade! :blush:
...oh, and I LOVE my pair of 4-400Cs in a homebrewed GG amp! 4600v / 1.25a
I guess it's critical that the upwardly going radials begin right at the hub, perhaps drilling holes into a radial hub plate for close mounting would make the difference?
What was your Gamma Match?
looking at the diagram for the SigmaIV the radials are mounted well above the bottom hub. mine are at the hub, but doesn't do the job properly at that point, or so i suspect. . . .
the gamma is a homebrew.
I appear to be unclear in my reference, but I am speaking of the 16 1/2" distance up the center aerial from the bottom of the antenna as shown in the SigmaIV assembly instructions.
http://www.cbtricks.com/ant_manuals/avanti/av174/graphics/sigma4_av174_om.pdf
Maybe I'm wrong?
I don't know if you're wrong or not. I'm the one that is confused about what you said. You said the Sigma 4 radials were mounted well above the bottom hub in your post, and I think that is wrong. That is why I raised the question. I thought maybe you were talking about the Penetrator 500 instead, which does raise their radials above the bottom feed point hub.
If I am still misunderstanding your point, what is significant regarding this 16.5" part of the bottom of the main radiator below the hub? Are you suggesting this may be why your homebrew Vector is not working up to par?
Here's where I went wrong - It is not above the hub on the SigmaIV, seeing the feedpoint is at the bottom of the radials, not the bottom of the main aerial (or the hub) as it is on my homebrew. I said what I meant poorly. Yes, I was referring to the the 16.5" as you noted, and I was suggesting that the radials being higher up the main vertical aerial is likely why mine, being at the base of the main aerial, is not performing properly.
I think it has something to do with matching/performance as the open sleeve does on a sleeved monopole, or even the 1/4 wave stub on the J-Pole. No, I don't think the SigmaIV is a fancy J-Pole, but I do suspect the whole thing with the radials seems to be highly influential in the overall performance of the antenna. i do not have the deeper knowledge some here on the forum have, so I have to just physically wrestle with the mechanical aspects of the antennas I've played with.
I will test my thoughts by pulling down the antenna and rebuilding it closer to the form the SigmaIV model has. Then I'll check its performance against the simple closed-sleeve 1/2 wave monopole that is presently kicking its butt in every way in terms of observable transmit and receive.
I understand now, but I disagree that this small 16.5" section of tubing has much if anything to do with the performance or tune of your antenna. When I look at the image below that you provided us in the "Modified Vector 4000" thread, I see that piece in the mast of your roof mount, so it's not missing.
I think you're correct that the relationships for all of the elements in the bottom of the Vector are critical to the performance and tune.
I find from personal experience with my Sigma 4 that the precise gamma position in the space between the two radials can make a big difference in the resonance. I never did get to really test performance, but I didn't notice any performance affects while my gamma was skewed a bit. My resonance was high in frequency and I had to add a longer element to the tip to get to 27.205. I wondered why, so I was looking for some other measurement issue somewhere else on the antenna. I felt the antenna was designed for the middle of the 40 channel CB band or maybe even lower for the old 23 channel days, but not higher. When I fixed the gamma position in the middle, the antenna responded as it should and I was able to use the stock element in the tip. I was surprised at that, and don't think I would have noticed it if I was just looking at SWR to tune. I know that Bob saw improved results and I think he only used a SWR meter, but my analyzer results never did look good. I always showed and unacceptable amount of reactance at the best SWR.
I also think the space between the bottom of the radials and the radiator is an important dimension to consider. In the pictures it is hard to tell, but this radial space on the Vector looks to be a bit closer than my Sigma 4. Homer, your radials look to be very close, maybe even touching the radiator where they mount. It is not the touching that matters, but maybe the close spacing. I don't know for sure if being close could be an issue or not. If helpful, the gamma spacing on my Sigma 4 is a bit more than 1" from the center of the gamma to the OD of the radiator. This measurement is taken at the bottom, measured at the bolts. At the tap point, the center of the gamma rod is about 5" from the OD of the radiator. Again, I think maybe the space between the gamma and the radiator is critical. Maybe the unusual angle of the gamma and being parallel with the radials instead of the radiator also has some affect on the tune as well.
I think you're correct that the relationships for all of the elements in the bottom of the Vector are critical to the performance and tune.
I find from personal experience with my Sigma 4 that the precise gamma position in the space between the two radials can make a big difference in the resonance. I never did get to really test performance, but I didn't notice any performance affects while my gamma was skewed a bit. My resonance was high in frequency and I had to add a longer element to the tip to get to 27.205. I wondered why, so I was looking for some other measurement issue somewhere else on the antenna. I felt the antenna was designed for the middle of the 40 channel CB band or maybe even lower for the old 23 channel days, but not higher. When I fixed the gamma position in the middle, the antenna responded as it should and I was able to use the stock element in the tip. I was surprised at that, and don't think I would have noticed it if I was just looking at SWR to tune. I know that Bob saw improved results and I think he only used a SWR meter, but my analyzer results never did look good. I always showed and unacceptable amount of reactance at the best SWR.
I also think the space between the bottom of the radials and the radiator is an important dimension to consider. In the pictures it is hard to tell, but this radial space on the Vector looks to be a bit closer than my Sigma 4. Homer, your radials look to be very close, maybe even touching the radiator where they mount. It is not the touching that matters, but maybe the close spacing. I don't know for sure if being close could be an issue or not. If helpful, the gamma spacing on my Sigma 4 is a bit more than 1" from the center of the gamma to the OD of the radiator. This measurement is taken at the bottom, measured at the bolts. At the tap point, the center of the gamma rod is about 5" from the OD of the radiator. Again, I think maybe the space between the gamma and the radiator is critical. Maybe the unusual angle of the gamma and being parallel with the radials instead of the radiator also has some affect on the tune as well.
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