I have, Booty.
The distance between the bottom of the CH and the top of the coil is 1", as is mine.
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Homebrew Merlin Experiment
- Thread starter HomerBB
- Start date
The distance between the bottom of the CH and the top of the coil is 1", as is mine.
That's about as close as you can get with the 'size' of any antenna. I would think that the dimensions of the capacitor hat and coil would be the only 'fixed' measurements, the rest will vary with each installation and tuning.
Any/all antenna modeling programs are only approximations, never absolutes. That's because the information output is only as 'accurate' as the input information and it's comprehensiveness. There's also the choice of 'best case' and worst case' in the information output. The 'best case' is a truly 'isotropic' result, never 'real world'. The 'worst case' is going to be much closer to the 'real world' results but will still only be an approximation. How do you enter all of the pertinent information in a real world installation, such as the electrical characteristics of a tree/house/whatever? I'm sure it's possible. But who has the ability and equipment (finances and time) to do that measuring?
Does that mean that I think all of this is a waste of time? No! But you do have to keep the results in perspective.
- 'Doc
Any/all antenna modeling programs are only approximations, never absolutes. That's because the information output is only as 'accurate' as the input information and it's comprehensiveness. There's also the choice of 'best case' and worst case' in the information output. The 'best case' is a truly 'isotropic' result, never 'real world'. The 'worst case' is going to be much closer to the 'real world' results but will still only be an approximation. How do you enter all of the pertinent information in a real world installation, such as the electrical characteristics of a tree/house/whatever? I'm sure it's possible. But who has the ability and equipment (finances and time) to do that measuring?
Does that mean that I think all of this is a waste of time? No! But you do have to keep the results in perspective.
- 'Doc
id like to see a review on performance between the A/P and merlin hommer.
at long distances of 20-40 miles [or more] with low power. these kinda test
i find helpful.nothing fanacy just what works at a given distance and what doesnt.
at long distances of 20-40 miles [or more] with low power. these kinda test
i find helpful.nothing fanacy just what works at a given distance and what doesnt.
Homer, Booty is right, there are more dimensions that are important to consider if your buddy will help me/us. See if it is possible he can give you all the dimensions, length and diameter, for each piece of tubing in the whole antenna including the top hat, plus the flat stock used in the coil. The overall length, height, and width for the whole coil would be helpful for my model too.
The dimensions for the small part(s) between the coil and the top hat are very important, because this is where the current starts to decline dramatically into the voltage phase, and it does it over this very small length and diameter...which BTW looks to be much larger that the 1/2" tubing I think is at the top.
It would be nice of we could get all of the dimensions, but that can be intensive work if done accurately.
BTW, I can't read the length for the radials, but it looks like it could be 101.25" rather than 1". How say you.
Copy and Paste from another forum written by a Merlin owner:
The top of the antenna looks basically like the Immortal. All aluminum. Cross on top. 2 turn coil just like the mobiles ( this is the new immortal and 100k watt whipping stick design) The top is a 1/2 in shaft aluminum. Bottom is 1 inch. Very heavy duty. Total tuned length is 72 inches from the top of the insulator. The 3 ground radials drooping at around a 45 deg angle are 101 in long. This antenna is short (1/2 wave) and easier to hide. . .
Tuning.. this antenna can be tuned with a tape measure and be about dead on. 71-72 in from the insulator should do the trick. 101 on the ground radials. And if any adjustment is needed it will be very little.
The top of the antenna looks basically like the Immortal. All aluminum. Cross on top. 2 turn coil just like the mobiles ( this is the new immortal and 100k watt whipping stick design) The top is a 1/2 in shaft aluminum. Bottom is 1 inch. Very heavy duty. Total tuned length is 72 inches from the top of the insulator. The 3 ground radials drooping at around a 45 deg angle are 101 in long. This antenna is short (1/2 wave) and easier to hide. . .
Tuning.. this antenna can be tuned with a tape measure and be about dead on. 71-72 in from the insulator should do the trick. 101 on the ground radials. And if any adjustment is needed it will be very little.
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hotrod,
I don't have an AP right now, and had not planned to build another until Spring. Any cash available will be taken in by the Christmas season, so w'll have to put that one off until then.
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B
BOOTY MONSTER
Guest
those same comments are also in a thread on this forum .
http://www.worldwidedx.com/cb-antennas/28783-new-55-merlin-base-antenna.html
that same thread/post also offers some other info ....
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" ........ Well to test the neighbor issue I put some mild improper english out ( yes i know im a bad boy) to try and prevoke her to call. She is a pain in the butt and when i put out my " please ring my phone 2 times" announcement she doesnt always call. not a plesant or cooporitive person. Any how no phone call. So far so good with bleed over with a uniden 78 and magna 200.. Note the lop of coax. this was needed with the I10k to cut down on bleeding since 5/8 wave antennas are notorious for signal comming down the coax. I just didnt take it out and have to restrap the whole tower again.
signal reports so far are identical to the intercepter 10k. Remember this is a 1/4 wave antenna. But it is wayyyyyy more broadbanded then the I 10k. And is much less wind load then the I10k. In the same day I changed antennas we had skip, nothing on the I10k, changed to the merlin and I got out on ch 6 with my uniden and magna 100.
This antenna needs to be tuned at 15 ft or more above the ground. ...... "
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apparently the user didn't have the bleed over problem you have homer and they were also using a coax choke . it's also said it need a minimum 15 ft tuning height , but it seems this test was done at 75 ft . i am confuse by the user saying signal reports were identical between the merlin and a i10k (5/8 GP) and then in the same paragraph saying the i10k didn't hear skip and then saying the merlin made contacts (i'm guessing it herd skip to confirm the contacts) . but maybe/apparently he's comparing local results (which were identical) to skip contacts ( which had a great deal of difference) ....
Until I get a 5/8 GP together over the next few days I have put a vertical Dipole up for comparison to the Merlin.
The dipole is constructed of wire within fiberglass crappie poles, and is a common center fed type.
Both Of the antennas are mounted at the same top tip height of 43'.
The Cap Hat on the Merlin is at the same upper elevation as the tip of the upper end of the dipole.
According to an operator about 2.5 miles distance from me, the dipole was the best for dead key and forward drive.
Without knowing what antennas I was operating, nor which I was at the moment keying/modulating he simply reported that the dead key was "8 swinging to 9 on that one" and "it's a little above 8 swinging past 9 on that one and you sound a little clearer"
Such a report, if his meter could be trusted on his RCI2995, would indicate around 3db (half an S-unit) of improvement from the Merlin to the Dipole, or twice the power out of the antenna and into his receive. My radio output is a modest 1 watt DK swinging to 4 watts AVG on both antennas. Draw your own conclusions about what he saw and why . . . SWR on both is 1.0:1 on 26,755 AM.
Naturally, with the characteristic lobes of each antenna at different elevations there would be a difference to be expected.
There in lies what may be the reason some report improvement that seems out of character to a particular antenna. Where is the RF strongest, and where are the stations that are reporting dramatic differences between one antenna over the other.
Perhaps by Monday or Tuesday I can have an operating 5/8 GP to replace the vertical dipole. We'll see . . .
The dipole is constructed of wire within fiberglass crappie poles, and is a common center fed type.
Both Of the antennas are mounted at the same top tip height of 43'.
The Cap Hat on the Merlin is at the same upper elevation as the tip of the upper end of the dipole.
According to an operator about 2.5 miles distance from me, the dipole was the best for dead key and forward drive.
Without knowing what antennas I was operating, nor which I was at the moment keying/modulating he simply reported that the dead key was "8 swinging to 9 on that one" and "it's a little above 8 swinging past 9 on that one and you sound a little clearer"
Such a report, if his meter could be trusted on his RCI2995, would indicate around 3db (half an S-unit) of improvement from the Merlin to the Dipole, or twice the power out of the antenna and into his receive. My radio output is a modest 1 watt DK swinging to 4 watts AVG on both antennas. Draw your own conclusions about what he saw and why . . . SWR on both is 1.0:1 on 26,755 AM.
Naturally, with the characteristic lobes of each antenna at different elevations there would be a difference to be expected.
There in lies what may be the reason some report improvement that seems out of character to a particular antenna. Where is the RF strongest, and where are the stations that are reporting dramatic differences between one antenna over the other.
Perhaps by Monday or Tuesday I can have an operating 5/8 GP to replace the vertical dipole. We'll see . . .
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B
BOOTY MONSTER
Guest
Hey Booty and Homer, how do y'all determine antenna lobes and where they are at different heights?
Now Marconi, you are baiting us into saying "by looking at models" 
Of course, I doubt anyone is looking at lobes before they take down their current antenna and put up a Merlin. I think it may be coincidental in some cases reporting great favorable differences that the stations of interest to them are positioned more favorably.
Which brings me to the idea of what would a Merlin and a dipole mounted vertical look like at vertically polarized 43' top height?
Of course, I doubt anyone is looking at lobes before they take down their current antenna and put up a Merlin. I think it may be coincidental in some cases reporting great favorable differences that the stations of interest to them are positioned more favorably.
Which brings me to the idea of what would a Merlin and a dipole mounted vertical look like at vertically polarized 43' top height?
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B
BOOTY MONSTER
Guest
i don't know how to determine antenna lobes through just using a antenna marconi . but let me put it a different/longer way . since i saw for myself how little effect going from 200 watts pep to 500 watts pep (about a 4 db difference) has on TX i don't care about the 1 or 2 db gain differences in omnis in the real world . but at pretty modest feed-point heights on fairly level areas i have seen/herd or been told of significant differences in the few antennas i've made . but i only care about improving on signals that i could barely hear before because of their distance . improving line of sight or ground wave signals locally doesn't interest me (i figure the closer proximity will keep us talking even if meter strength is reduced) but improving LOS/GW down the road does . as for skip , as long as i can keep up with other folks within a few to several miles of me or make my fair share of contacts i figure i'm doing OK . i seem to have done better with antennas that are said to have lower TOA or stronger radiation @ lower angles ... thus my previous post . it seems to me that it's more important where the signal is going coming off the antenna , than how much signal overall is coming off a antenna . but i'm not interested in a stronger local signal to "lock down the town" ...... not that i could with 200 watts .... and a omni
. LOLanyhow ..... the conversations here about TOA and lobes seem to explain why i got the results i have .
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Now Marconi, you are baiting us into saying "by looking at models"
Of course, I doubt anyone is looking at lobes before they take down their current antenna and put up a Merlin. I think it may be coincidental in some cases reporting great favorable differences that the stations of interest to them are positioned more favorably.
Which brings me to the idea of what would a Merlin and a dipole mounted vertical look like at vertically polarized 43' top height?
Well Homer, you're right to a degree. That is all I can come up with unless y'all were using Needle Bender's idea...using the florescent light bulb and mapping the results. :thumbdown:
Right now I'm covered up in models, just trying to get the A/P - Merlin models equal in their settings and trying to make the comparison as fair as I can.
I wasn't expecting all this when the Merlin idea popped up, so I was not preparied. It turns out now that I had to consider using a mast in the project, because the A/P requires a mast as part of the antenna matching.
When I added the mast to the Merlin @ 36' feet, where I made the previous models, the Merlin pattern went to heck in a hand basket and I think that has something to do with that particular height at 27.205, but I can't prove that. That said, and I hadn't even started on trying to get the two models on an even par with the settings.
But I took a break and checked out your request for the dipole vs. Merlin at 43' feet to the tips. Notice I isolated (ISO) the mast from the antenna to help duplicate your Merlin setup.
View attachment Homer's 43' comparison..pdf
How say you?
B
BOOTY MONSTER
Guest
since some of the merlin claims were made using a tower that gave the merlin a 75 ft feed-point why don't you try modeling it at that height to see how your models compare with those claims ? BTW , will a tower under a antenna make it behave differently than a typical mast/pole since the tower is so much bigger and has more mass ?