JAFO said:
.....I was told the Avanti Sigma 5/8 was a better antenna so I bought one and tried it against the Penetrator.
(snip)
It was a tough decision but I ended up keeping the Penetrator because I thought the Sigma's 'wire'-ended radials seemed cheaper than the Penetrator's full-tubular radial design, and I preferred the Penetrator's radial mounting over the easily cracked aluminum radial hub of the Sigma 5/8.
Isn't Jay's Interceptor match simply an unfolded Sigma 5/8 or Maco V-5/8 'T' (ring) match?
The Avanti Sigma 5/8 IS a better antenna than the Penetrator. As pointed out, the differences are slight, but they do exist.
The stainless steel wires were added to the ends of the radials for one reason; it was less expensive and easy to do. Electrically, the end of the radials see high voltage and the use of the stainless steel stinger does not affect what the vertical signal sees. In other words, it was less expensive and worked just as good.
I never had any problems with cracked hubs. I know people do, but I haven't seen it. There were two versions of the Penetrator; one used two bolts to hold the radials and the other used one bolt. The two bolt version is prefered.
The loop on the Avanti is nothing like the loop on the Maco. On the avanti, it makes up for the missing 1/8 wave required to take the antenna to the next "1/4 wave increment" to allow the antenna to be fed with a 50 ohm feedline. It is horizontal in order to keep it from skewing the vertical radiation of the antenna. Later version of the Sigma 5/8 (after the Antenna Specialist buy-out) used a small coil inside the tube in order to make the antenna DC grounded. Earlier version of the Sigma were NOT DC grounded. This coil required Antenna Specialist to slightly lengthen the antenna to compensate for the electrical changes to the original design.
The Avanti uses an ELEVATED feed system. The Penetrator (and the MACO) do not. During early discussions with Jay, as the Mastadon 5000 was being developed (the I-10K was not even on the drawing board yet), I pointed out that the Avanti used an elevated feed and that the loop was placed in the horizontal plane for the reason I gave above. The Mastadon was a direct copy of the Penetrator except for an upgraded feedpoint (still with the vertical hairpin). As the tests and the years progressed, Jay came to the conclusion that the "Penetrator" design still had flaws. The I-10K was born and it uses a reconfigured loop (in the horizontal plane) and an elevated feed. The new matching network IS adjustable on both sides of the "tap" as Eddie pointed out.
Jay took the best of the best (Sigma and Penetrator) and came up with the I-10K (undisputed world champion antenna).
I could go into detail about the flaws of the Maco antenna. Yet, it is still a good antenna and I recommend it for those on a buget. My exact words are, "If you can't afford an I-10K, at least get a Maco V58!" Stay away from the iMax and the A99! From a leter post, you speak about PHYSICALLY lengthing the Maco in order to achive a true 5/8. You can't look at it that way! You have to look at an antenna ELECTRICALLY. I rebuilt/upgraded a couple of Maco V58 where the owners stated that it was IMPOSSIBLE to get a flat match on them. I was able to and they were floored! The difference was, I tuned both the ring tap AN the physical length pf the antenna to get the desired results. I used a Bird 4030 in a Bird 43 to show the "before" and "after". Using the same mounting (tower), feedline, and antenna, they saw an increase (slight) in transmit and receive signal strength. Still, the mounting of the vertical element to the base section of the Maco is still a design flaw and contributes to it's inability to handle big power.
I have yet to see a Wolf Radio antenna. I'm thinking of buying a .64 just so I can speak intelligently about it. I certainly can see the merits of the concept!
I still have the original e-mails from the discussions Jay and I had back in the late 90's. I shipped him a Sigma 5/8 from Colorado so he could do tests agains the Mastadon. I also have the e-mails from one of Avanti's engineers where he educated me on their use of the stainless steel stingers and the fact that the Sigma IV is a variation of the standard J-Pole (It was nice to see Eddie point that out with no coaxing from anyone! I bet some of you shivered when he said that!
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Over the years, I have collected and rebuilt MANY Avanti antennas! I especially like the Sigma 5/8 an have copies of both the old and newer versions. I also have a number of original Sigma IVs in the garage (no, they are not for sale).
I hope I was able to answer a few of your questions. If you have more questions, let me know.
Eddie, If you want an unbiased test bed for the dual angle prototype, let me know. I love the idea! It's so simple, why haven't people done it in the past? Maybe its he $$$! Ham radio dudes used stacked arrays (horizontal yagis) and are able to switch which antenna is being used (at different heights) in order to change their takeoff angles. A local ham gave me (as a young teenager) a tour of his station and taught me that by changing the height of his single yagi (motorized crank-up tower), he could hear the East Coast or Europe. It was a live demo and like a picture, said a thousand words! I have a 40' tower trailer and make runs out to the high desert to test antennas.