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Base HY-GAIN PENETRATOR vs Maco V58
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Wow, just wow.
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You still missed the point that we were trying to make, and now you try to reframe what has been said, or at least why it was said...
No one said length isn't important, although I would differ as to why it is important and how it affects the antenna. Saying/presuming that I said otherwise is just being dishonest.
The biggest difference between what you and I are saying when it comes to antenna length is scale. The rest is simply me factoring in things that you refuse to consider might have an effect...
I wasn't treating you like a fool, I was treating you like you had potential for growth. Perhaps I gave you to much credit?
The DB
Wow, just wow.
...
You still missed the point that we were trying to make, and now you try to reframe what has been said, or at least why it was said...
No one said length isn't important, although I would differ as to why it is important and how it affects the antenna. Saying/presuming that I said otherwise is just being dishonest.
The biggest difference between what you and I are saying when it comes to antenna length is scale. The rest is simply me factoring in things that you refuse to consider might have an effect...
I wasn't treating you like a fool, I was treating you like you had potential for growth. Perhaps I gave you to much credit?
The DB
Chop the radiator all the way down to half wave, peel a little off the top half of the matching inductor to accommodate the lower impedance and you may have lost a just over 1/6 of an s unit or 1db going all the way down to a 1/2 wave. That's with a change to both the physical and electrical length of the radiator. In the case of the SP-500 vs. the Maco V58, the difference is a small change in physical length but the electrical length of the radiator is still 5/8 wave because of the capacitive reactance in the base mount.
The SP-500 sat on my roof for several years during the 1980's. It's a great antenna that never disappointed me. Having said that, I can't say there was any difference in performance when compared to the Radio Shack .64 wave it replaced. The only difference was the Radio Shack burned its PC board inductor up with the D&A Warrior but the heavier gauge aluminum wire on the SP-500 did not.
One of the 4 wires on the top of my SP-500 broke off from bird landings. When that happened, I took the screw out of the top to remove all four, lengthened the radiator about an inch or two until the VSWR dropped back into place and could not see any signal changes there either.
The SP-500 sat on my roof for several years during the 1980's. It's a great antenna that never disappointed me. Having said that, I can't say there was any difference in performance when compared to the Radio Shack .64 wave it replaced. The only difference was the Radio Shack burned its PC board inductor up with the D&A Warrior but the heavier gauge aluminum wire on the SP-500 did not.
One of the 4 wires on the top of my SP-500 broke off from bird landings. When that happened, I took the screw out of the top to remove all four, lengthened the radiator about an inch or two until the VSWR dropped back into place and could not see any signal changes there either.
If only most of what you wrote wasn't false.
When you shorten a 5/8 down to a 1/2 wave the impedance goes up not down because an end fed 1/2 wave is the highest impedance point an end fed antenna will be, that of around 2500 ohms +/-
or the equivalent of about a 50:1 SWR - before the matching network.
The capacitive reactance added to the bottom of the MacoV58 offsets the inductive reactance of the too-long 19' 8" radiator because the Maco is not fed at the point of maximum current as is the 5/8 Penetrator but at a point of high voltage, via it's curved shunt match, as an elongated half wave, and why I avoid using one as I do not appreciate RFI in the shack, as voltage fed antennas are notorious for causing.
The 1dB gain of the Penetrator over the MacoV58 you're referring to is near-field only, or what you might see at 1-10 wavelengths at an antenna testing range but the real test is at or beyond the horizon where the difference between the MacoV58 and a Penetrator has been up to 2 s-units in favor of the full 5/8 wave Penetrator.
If you removed all four 9.5" top rods you would not have been able to achieve a low swr/ low reactance condition much below 28.5mhz because there isn't enough extra material telescoped inside since Hy-gain cut their Penetrator tubing to just enough for a tuned condition at 27.0
And You would have needed much more than just a couple inches.
An additional 9.75" of exposed 5/16" tubing would be required for a tuned condition at 27.185mhz after cutting off the top 3/4" of tubing housing the threaded aluminum insert.
Come on Donald, I thought you were smarter than that.
The point was when you shorten a 5/8 wave down to a 1/2 wave, you could lose up to 1.2db once you compensated for the impedance change. Seeing more than that within various 5/8 wave designs is a likely sign that other things were at play.
I wasn't saying the SP-500 has 1db over the V-58 either. I was saying that a 5/8 wave with a good ground plane under it could achieve about 1.2db over a 1/2 wave. Those are not near field differences but what you could expect in the distance. Keep in mind the end fed 5/8 wave is very dependent on an effective ground plane to hit those numbers and the SP-500 and V-58 are about equal there too.
You are probably right about there not being enough material in the SP-500 to compensate for taking the top hat off. It's been a long time since the 1980's but that would have delayed the retune one trip down the ladder to get another piece off the old RS it replaced. Not a memorable event. The point there is, it was easily be retuned without the top hat and without losing any performance.
It's not about "who's smarter than that" or more endless debate about antennas. If you've had a different experience than others, that's fine. Just trying to encourage you to look for the reasons.
I wasn't saying the SP-500 has 1db over the V-58 either. I was saying that a 5/8 wave with a good ground plane under it could achieve about 1.2db over a 1/2 wave. Those are not near field differences but what you could expect in the distance. Keep in mind the end fed 5/8 wave is very dependent on an effective ground plane to hit those numbers and the SP-500 and V-58 are about equal there too.
You are probably right about there not being enough material in the SP-500 to compensate for taking the top hat off. It's been a long time since the 1980's but that would have delayed the retune one trip down the ladder to get another piece off the old RS it replaced. Not a memorable event. The point there is, it was easily be retuned without the top hat and without losing any performance.
It's not about "who's smarter than that" or more endless debate about antennas. If you've had a different experience than others, that's fine. Just trying to encourage you to look for the reasons.
Ok, see, you ARE smarter than that since you rewrote most of your previous post more correctly, or with excuses for the errors,
except when you stated the fallacy,
"Those are not near field differences but what you could expect in the distance"
Because I would not expect something other than the 1-2 s-units improvement FROM a MacoV58/5000 TO a Penetrator which I've experienced time and time again.
Contrary to yours and the db's mistaken expectations and belief, if an increase of at least a full s-unit wasn't achieved when replacing a MacoV58 with a full 5/8, such as a Penetrator, only THEN would I begin to search for a system malfunction.
And reasons are the very thing I'm offering, apparently much to the dismay of a few who seem to wish to avoid them and muddy the waters with vagaries such as, "Your experience" etc.
The voltage fed 19'8" MacoV58 elongated 1/2 wave is a very different performing vertical omni than a full 5/8 wave such as the Penetrator and would only provide preferred performance when operated rather deep in the hills or mountains due to it's higher radiating angle (where a simple 1/4 wave ground plane would probably perform even better) or possibly within very short skip conditions or backscatter.
except when you stated the fallacy,
"Those are not near field differences but what you could expect in the distance"
Because I would not expect something other than the 1-2 s-units improvement FROM a MacoV58/5000 TO a Penetrator which I've experienced time and time again.
Contrary to yours and the db's mistaken expectations and belief, if an increase of at least a full s-unit wasn't achieved when replacing a MacoV58 with a full 5/8, such as a Penetrator, only THEN would I begin to search for a system malfunction.
And reasons are the very thing I'm offering, apparently much to the dismay of a few who seem to wish to avoid them and muddy the waters with vagaries such as, "Your experience" etc.
The voltage fed 19'8" MacoV58 elongated 1/2 wave is a very different performing vertical omni than a full 5/8 wave such as the Penetrator and would only provide preferred performance when operated rather deep in the hills or mountains due to it's higher radiating angle (where a simple 1/4 wave ground plane would probably perform even better) or possibly within very short skip conditions or backscatter.
There isn't an S-unit (6db) difference between the smallest Starduster and the biggest Sigma IV let alone between two 5/8 wave models. To get 2 S-Units (12db) over just a 1/2 wave would take a directional antenna or 16 stacked dipole bays in a colinear omni configuration. Another way to look at those 2 S-units are it's equivalent to going from a barefoot 100 watt rig to over legal limit at 1600 watts. Does it still seem reasonable to say going from the V-58 to the SP-500 increased your Effective Radiated Power by 16 times or is it more likely we are seeing the results of the typical, inaccurate S-Meter?
JAF0, after rereading some of your posts I'm going to be upfront and say I see a lot of who I was a few years ago in you. Too much emphasis on being right, to be polite. Too much joy in showing others how false what they say is, to realize I could be wrong. Having to point out all the reasons why someone couldn't achieve what they claimed rather than trying to understand how they could come up with a different result. It all boils down to believing something to the point where we become more apt to argue than learn about how the differences we see are possible. That took the fun out of this for me for a few years. Don't be the old Donald.
JAF0, after rereading some of your posts I'm going to be upfront and say I see a lot of who I was a few years ago in you. Too much emphasis on being right, to be polite. Too much joy in showing others how false what they say is, to realize I could be wrong. Having to point out all the reasons why someone couldn't achieve what they claimed rather than trying to understand how they could come up with a different result. It all boils down to believing something to the point where we become more apt to argue than learn about how the differences we see are possible. That took the fun out of this for me for a few years. Don't be the old Donald.
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Im going to give this a try. I put it together in the basement and had plenty radiator to work with.
Casey New member Username: Casey Post Number: 8 Registered: 11-2010 Posted on Friday, May 20, 2011 - 9:18 pm: This excellent article about an old friend since 1974 needs to be kept alive. I believe the Penetrator is actually a .64. I believe they called it a 5/8 because .64 is so close to .625 and because all top antennas were 5/8 back in the day, so why call it anything other than what was selling at the time? Mine measures 274" of radiator for zero reactance and 1:1 swr on 27.385. If you add the average circumference of the radiator (.65 Pi = 2") to the 274" radiator you get 276" .64 of a full wave at 27.385 is 276" .625 of a full wave a 27.385 is 269.5" I get just about an s unit improvement over my Imax and about 2 s units more than my MACO V5/8. I saw about 1/2 s unit more than my I-10K until I extended the I10K to .64, then they were neck and neck at 75 miles. Rumor has it production of the Penetrator by MFJ will begin around July 2011, however, I believe it will be sold as a 10m / 12m Amateur radio antenna.
Hey old goat 321, I received an email yesterday from a friend in SoCal who just set up his spt-500 at 272.5" total above the radial plate.
I'm going to order up an spt-500 just to see how bad a copy of the original it is, and how it tunes.
Just analyze it if you have an MFJ analyzer available and if not, start with Kevin's 272.5" to the tip, no top rods or 9.5" shorter, 263" including the top hat rods and shorten as necessary to achieve the lowest SWR at the desired frequency, but make sure you bend the top hat rods down at a 45 degree angle if you keep them on.
FYI, the old school original Penetrator measured 260.5" to the tip where the 9.5" top rods connect but possibly used a slightly different "hairpin" match length and shape compared to the newer spt-500.
Kevin in SoCal hangs out on channel 20 so that's where he set his SWR. It should be around 1.5"- 2" shorter for 38 SSB.
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I think he is. I cant wait to get my spt 500 on top of my 40' tower. Brand new lmr 400. Hope i see a few s-units over my 20 year old a-99 with 20 year old rg8x mounted at 20'. But to be truthful , i think if i just set my radio up on top of the tower with out an antenna it might perform better than what i have now. Now, im not saying a penetrator is 2 s over a a99. What i am saying is i hope the new coax and penetrator and height and grounding equals a much better system.
Wow, 274" for Ch.38? I wonder if someone replaced the hairpin with one custom made and was a bit off on the measurements?
That might account for the extra radiator length.
YMMV (Your Mileage May Vary) as they say, especially if any mods have been made.
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