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New Super Penetrator 500
- Thread starter basstracker1970
- Start date
The GM was designed to cover all of 10 meters for the ham operator. Not for repeater use where the antenna needs a little more bandwidth to transmit the output frequency of the repeater. I had one situation where this was required and found if you cut about one inch off the top of the black wire inside the fiberglass you can raise the resonant point of the antenna for a near perfect match at 29.7 Mhz. Don't cut too much off because there is a point of diminishing return where the SWR will not go lower on 29.7 but will increase everywhere else.
Since it's a 10M repeater, and 10M cavity filter/duplexers are rather large, and very hard to find, it's a split site system. An individual GM at each site. Receive site is 29.520, and the TX is set for 29.620. SWR at 29.620 is 1.5:1. Good enough.
An antenna used for a fixed frequency system, whether a repeater of not, isn't required to have a wide bandwidth. In fact, the wider the bandwidth the less efficient the antenna.
- 'Doc
- 'Doc
I originally suggested a couple of Hy gain SPT 500's, but due to commercial site requirements, the site technician suggested some antennas without radials, so the GM it was. I still think we should have used Penetrators.
i was actually told this many years ago. so if i understand it correctly
the p-500,i10k,maco SHOULD be somewhat more efficient.
as a dummy load dont radiate at all [or very little]
Antenna is up, guy wires on and mast is about 18 feet . I've been informed that I should look at mounting it higher for extra coverage. There are telescopic masts that could achieve the extra height.
Spoke to a gent on the Gold Coast ( South east Queensland yesterday 1700 km) and got good reports as was he. Nice antenna. Thicker coax was given to me by a friend which also assists.
Bruce
looks good. hows it working for ya??? and have anything else to compare it too?
hows it doing for local chatting
Cheers Hotrod,
Local chatting is good considering that it needs to go higher. I visited a gent last night after work who manufacturers masts and he showed me some telescopic versions. I could mount one on the roof and it will extend to 30 feet. That plus the height of the roof would give me just under 40 feet to the base which would extend the TXing.
As for DX..I have been picking up Minnesota, Colorado, Hawaii , (sometimes West Coast of OZ ).
I did have a 1/4 wave but it has been down for a while now. I feel the 5/8 is a better antenna for my needs at the moment and later on will look at a Yagi for chatting long distance.
Bruce
Because there is truth in this statement and it does NOT apply to the GM, we should understand why and what the differences are. If the antenna had a matching network wound of light gauge wire and little surface area, it would have these losses. Using this type of transformer matching in a 5/8 wave would increase bandwidth at the expense of power handling and efficiency. The proof would be heating of the matching network causing failure before RF voltage breaks down the insulator and arcs.
We know that is one way to increase bandwidth but should be much more reluctant to paint this broad brush across every wide band antenna you find. Would you consider a long boom television antenna or a log periodic to be broadbanded due to extreme matching loss or inefficiency? Of course not because there are other ways to achieve wider bandwidth.
The TV antenna, Log Periodic and Gain-Master all use a similar technique to widen bandwidth. When different elements of an antenna are tuned to slightly different resonant frequencies that overlap, you get a wider bandwidth without the losses. That is easy for most to envision with the TV antenna and log periodic but may be harder to see in the GM.
The GM is a balanced antenna with a bottom element that has a tuning stub and top element that has a tuning capacitor. If we favor the top element at one end of the bandwidth and the bottom element to favor the opposite end of the bandwidth, then use the tuning cap and stub to flatten out the match in the middle, we get very wide bandwidth that's unfamiliar to many.
All you have to do is sweep the GM with any antenna analyzer to see the evidence of what I've just explained. No matching network gaining bandwidth from loss can produce two different resonant points. The fact the GM has two, so wide apart without a big increase in VSWR between them is an accomplishment.
LOL! Ohhhhhhh Kaaaaaay
Now go buy & try them, then report back your updated opinion
LOL! Ohhhhhhh Kaaaaaay
Now go buy & try them, then report back your updated opinion
From someone who has played with several different 5/8 wavelength antennas over the years, what he said is mostly true. Theory supports this observation as well.
In my experience, very few people would notice the difference between a Maco and any of the $400 plus 5/8 (and even .64) wavelength antennas. Is there a difference? Yes, the Maco V5/8 series antennas is a few feet shorter, and that, if anything, is the cause. That difference, however, is less than your s-meter will be able to show. The difference in gain between the two is next to nothing, if you are a believer in take off angles, the angle will be less than a degree of difference between the two as well.
The only other effective difference between the Maco and the high priced antennas is the matching system, and the matching system on the Maco's design isn't exactly lossy, there isn't really much room for improvement in this area, to the point that even if you somehow created a theoretical lossless matching system the difference would be, again, far to small for any s-meter to pick up.
The real benefit of the high priced antennas is not performance, but survivability. That being said, how many people do you know would spend $400 on their antenna and make any claim that it doesn't outperform everything else out there just because they spent the extra money?
The DB
It's a swing, and a STRIKE!
Sorry, not buying it. I've been on too many roofs and replaced far too many Imaxs with Maco V58s, then seen a fat S unit drop to all the regular locals, and visa-versa, maco gone, Imax up, PLUS 1 S-unit, to be fooled by 'same-same' talk.
THEN there's the Penetrator, another fat S unit stronger than the Imax, but the best example to my memory was last May, helping Mark erect a Penetrator where a Maco had been, the first report from a regular local op, "Hey that antenna is working! You were a 7, now you're a 9!"
- Bad Maco, right?
Nope, less than a month old, got talked into the Penetrator by a friend who saw improvement after replacing his Imax with one, and his Brother needed an antenna (the Maco) for his new location.
Again, it's all just anecdotal info, you'll have to experience it for yourself, over and over again, in order to get on frequency with those of us who have, and know.
But I will conceed that if it's an Interceptor, Penetrator, SigmaII 5/8 or any other 22'5" 5/8 (including the top hat length) sporting a respectively efficient matching network, it's a wash.
My post was addressing the ridiculousness of comparing a Maco V58 to a Penetrator.
Not everything that claims to BE a 5/8 IS a 5/8.
Sorry, not buying it. I've been on too many roofs and replaced far too many Imaxs with Maco V58s, then seen a fat S unit drop to all the regular locals, and visa-versa, maco gone, Imax up, PLUS 1 S-unit, to be fooled by 'same-same' talk.
THEN there's the Penetrator, another fat S unit stronger than the Imax, but the best example to my memory was last May, helping Mark erect a Penetrator where a Maco had been, the first report from a regular local op, "Hey that antenna is working! You were a 7, now you're a 9!"
- Bad Maco, right?
Nope, less than a month old, got talked into the Penetrator by a friend who saw improvement after replacing his Imax with one, and his Brother needed an antenna (the Maco) for his new location.
Again, it's all just anecdotal info, you'll have to experience it for yourself, over and over again, in order to get on frequency with those of us who have, and know.
But I will conceed that if it's an Interceptor, Penetrator, SigmaII 5/8 or any other 22'5" 5/8 (including the top hat length) sporting a respectively efficient matching network, it's a wash.
My post was addressing the ridiculousness of comparing a Maco V58 to a Penetrator.
Not everything that claims to BE a 5/8 IS a 5/8.
When it comes to the new Penetrators in comparison to the Imax antennas, I see the same thing you see, about 1 s-unit in difference.
However, you say the Imax beats the Maco's you set up? Strange, the Maco's I've set up and tuned perform about the same as the Penetrators. They beat the Imax antennas every time. I get an easy s-unit of difference between those two in favor of the Maco every time, over, and over again. The only place I've seen an Imax outperform a Maco is when its base is mounted within 15 feet of the earth.
You claim real world experience? Well, mine clearly disagrees with yours in this case. Something has to be different in either what we are doing, or perhaps environmental conditions in our areas, or something. I have never once seen an Imax outperform the Maco after one replaces the other at roof height or higher.
There is an exception to that never once, but imho it doesn't really count... A Maco was replaced with an Imax, and the coax, which was 200 feet of RG-8x with water damage, was replaced with 200 feet of new LMR-400. I disregard this setup because the significant upgrade in coax had more of an effect than any change in antennas. Yet he doesn't see the coax upgrade as having any effect whatsoever, and swears the Imax is the better antenna, go figure...
I have no problem with conceding (and already have above) that the smaller length of the Maco has an effect, however, its just not enough of a difference to have that much of an effect.
All that being said the antenna I find myself recommending almost exclusively lately is the Gainmaster. I often see that antenna getting an s-unit gain over other 5/8 wavelength antennas mounted at roof height or higher. It does however, need a certain amount of height to see those numbers...
The DB
However, you say the Imax beats the Maco's you set up? Strange, the Maco's I've set up and tuned perform about the same as the Penetrators. They beat the Imax antennas every time. I get an easy s-unit of difference between those two in favor of the Maco every time, over, and over again. The only place I've seen an Imax outperform a Maco is when its base is mounted within 15 feet of the earth.
You claim real world experience? Well, mine clearly disagrees with yours in this case. Something has to be different in either what we are doing, or perhaps environmental conditions in our areas, or something. I have never once seen an Imax outperform the Maco after one replaces the other at roof height or higher.
There is an exception to that never once, but imho it doesn't really count... A Maco was replaced with an Imax, and the coax, which was 200 feet of RG-8x with water damage, was replaced with 200 feet of new LMR-400. I disregard this setup because the significant upgrade in coax had more of an effect than any change in antennas. Yet he doesn't see the coax upgrade as having any effect whatsoever, and swears the Imax is the better antenna, go figure...
I have no problem with conceding (and already have above) that the smaller length of the Maco has an effect, however, its just not enough of a difference to have that much of an effect.
All that being said the antenna I find myself recommending almost exclusively lately is the Gainmaster. I often see that antenna getting an s-unit gain over other 5/8 wavelength antennas mounted at roof height or higher. It does however, need a certain amount of height to see those numbers...
The DB
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ive helped setup/erract macos, p500 and they always beat the imax . especially in the recieve much better with aliumin. ONLY time i seen the imax do better is when the base
height of the imax was higher then the maco/p500.also many have been saying now
the imax /a99 are merely dipole antennasand maco/p500 are TRUE grioundplane antennas
height of the imax was higher then the maco/p500.also many have been saying now
the imax /a99 are merely dipole antennasand maco/p500 are TRUE grioundplane antennas