Theory, and practice, are far different. There is NO substitution for experimentation.
I know a Ham in Detroit with a Hustler Vertical with NO Radials on a 5 story apartment building, who does just fine. OK, the RF is going somewhere, maybe the rebar, furnace vents, or electric wires in the building are providing the missing 1/2 of the antenna, but something sure is.
LOL, we scared him so bad, he put RF Chokes in his coax, and his vertical still works.

I have to agree, I would simply fix and reinstall the G5RV.

But I would still keep my eye out for a used vertical, and TRY it, see what happens ?
If it works, keep it. If not, sell it. If you buy it used, you will not lose money.

Wow, the bottom antenna is pretty low ? Would you not have been better off to use a single 4 or 5 element Yagi at 54 feet, vs the stack of 2's ?

WHY ground it, at all ? Is not that kind of like ASKING for a lightning strike ?
I live in Tampa, we get a lot of lightning here. Plenty of ungrounded verticals on chimney mounts down here, never heard of any ungrounded verticals ever getting hit.

Merry Christmas to you too Mike! No "fuss" really, just a bunch of bored old guys, talking about design compromises in our antennas.
As G3TXQ  correctly pointed out, trap, no trap, or full size trapless monobanders, ALL are a compromise, in one way or another.
I think it as all about finding the right compromise for YOU, and your operating habits.

I own the Hy Gain Explorer 14, with the 40 meter add on kit for instance Mike. I wanted a small (no more then 14 ft boom) tribander, with the best 10 meter performance I could buy, on that boom length. The Hy Gain Explorer 14 is almost a "monobander" on 10 meters, compared to any other tribander I could buy, on that boom length. It has dual driven elements on 10 (no traps) and a trapless, full size separate 10 meter reflector. Only the director element has a trap in it, for 10 meters.
W4RNL felt the dual driven element feed system used for 10 meters in the Explorer 14 (Hy Gain calls it a Para Sleeve) give a small amount of extra gain vs a single dipole feed.
It also gives great 10 meter bandwidth as well!
I think the Hy Gain Explorer 14 is overall the best 14 foot boom tribander money can buy, and certainly the best on 10 Meters. Like I said earlier, 10 meter performance is a MUST for me. I feel Roger Cox did an awesome job on the Explorer 14 design, and made the right compromises for me, and what I want and expect, from a small tribander.

I am up at 50 feet, pretty much the same height as my friends, one who has the 24 foot boom Hy Gain 10 meter monobander, and one who has the 4 element SteppIR.
WE are all within 20 miles of each other.

DO I kick their butts ? Heck no, the 24  foot boom computer optimized 10 meter Hy Gain 10 meter monobander is king, followed by the 4 element SteppIR, then my little Explorer 14.

But, I am "right in there" with the big boys. Both of my friends constantly comment on the clean pattern the little Explorer 14 has, on 10 meters.
I live near Tampa, and often have 1/2 of South America trying to bust into the back of my beam. Often, I can hear stations with less interference then they can, but I just can not match the firepower of the 24 foot 10 meter Hy Gain monobander.
The 4 element SteppIR does not have the firepower of the Hy Gain 10 meter monobander. The signal differences between him and me are not nearly as great as me and my Exporer 14 vs the Hy Gain 10 meter monobander.
So, I feel like I made the right choice, for me/

Now, interestingly enough, we have another Ham Friend who has a small Hex Beam.
He is only up at 38 feet (we are all at 50 feet) though. He has truly excellent rejection on his little Hex Beam.
In fact, this is his SECOND Hex Beam! He started out with a Traffie Hex Beam, and did very well with it too. But, he was less then thrilled with the lack of front to rear rejection, on 10 meters. I told him all about the KIO Hex Beams, and how Steve Hunt was able to get better rejection with his design. So, he took the Traffie Hex Beam to a Ham Radio Tailgate at the last Tampa Hamfest. It sold right away!
USED Hex Beams are nearly impossible to find here in Florida. WE have many retired Hams (winter only residents) who want a small, decent performing lightweight beam antenna, they do not have to worry about in every thunderstorm.
He was able to get 400.00 for the used Traffie Hex Beam, put a few hundred dollars more with it, and ordered the K4KIO Hex Beam.
I remember both antennas well, and the KIO Hex Beam did exactly what he expected, it greatly reduced the South American interference.

So, getting back to the thread, it is all about compromises. Like me, my Hex Beam owning friend found the right compromise for him.

Maybe because he is 12 feet lower in elevation then us, the signal from the KIO Hex Beam is nearly always from 1/2 to 1 S Unit lower then we are. I am sure the little 2 element Hex Beam just does not have the gain the 3 of us have, but it was the right compromise for him.
So many antenna makers IMHO seem to always push Gain as their reason for existence. IF I had told my Ham Friend that the KIO Hex Beam had more gain then his Traffie Hex Beam, I feel quite sure my friend would have kept the Traffie.
But, because Steve Hunt chose to offer better front to rear rejection in his KIO Hex Beam design, his design was chosen as a compromise my friend was willing to accept, and BUY!

The Force 12 owning ham in this thread bought the N6BT Force 12 design, because it does what HE wants it to do.

He appears to be as happy with his choice of antennas, as I am with my Hy Gain Explorer 14 semi trap design.

And, my other friend, with the 24 ft long Hy Gain 10 meter monobander, bought his Yagi, as the ONLY antenna on his tower! He sacrificed all the other HF Bands, to be "King Chit" on 10 meters.

Guess what, not surprisingly, it worked! It truly "messes with him" though, that he does not "kill us" with the big monobander.
But, never underestimate a determined Ham!
The last time we talked, he sent me to the M2 web page, to look at the 42 foot long M2 7 element 10 meter monobander 

LOL, and my Guy wires "act as reflectors and directors" for my Beam, but wait, there's more! I have a metal scarecrow (Obamacrow) on the very top of my antenna mast. And, the dimensions of this metal scarecrow was arrived at by computer simulation, to act as a director at multiple HF frequencies!~
You can read all about it, in my book, called "A Bunch Of Bullchit"

I agree that putting a smaller antenna up higher is a great idea! That is why Hex Beams are so popular. They are lightweight, and easy to stick up in the air, w/o heavy duty tower considerations.
But, wait a moment ?
I remember reading the best overall height for a triband beam antenna based in Newington, CT was only 52 feet!
I read this in QST
Do any of you guys remember that article ?

Hi Steve! Good to see you over here! Where do you stand on the Trap Loss Debate ?
I know you do a considerable amount of computer modeling. Is it not also true that any non trap interlaced Yagi for 3 or more bands will have some element interference that may effect it's performance ?

Trap Loss, or lack of it, in triband beam antennas, has always been a subject I have wondered about.
I just Googled "Trap Loss W4RNL" to see what he had to say about this matter of interest to me.

Check it out

The Effects of Traps on Beams

Experience has shown that the losses in gain of center loaded elements are additive, at least in 2-element Yagis. If this experience holds true of the 14.1 MHz elements with 15-meter traps, then one might expect about 0.5 dB loss of forward gain relative to a full size Yagi of the same design but unloaded.

To test this hypothesis, I scaled a 10-meter beam with a 50-ohm feedpoint impedance for 14.1 MHz. The new full-size beam spaced the elements by 12.12', again using 1" aluminum tubing for modeling simplicity, as shown in Figure 3. With a driven element 32.2' long and a reflector 34.94' long, the beam achieved its maximum front-to-back ratio (10.68 dB), a figure almost exactly that of its 10-meter counterpart. The resonant feedpoint impedance was 50.7 ohms. The forward gain under these condition was 6.13 dBi.


If a beam using two trapped elements could be constructed with a comparable maximum front-to-back ratio and a comparable feedpoint impedance, then the gain difference between it and the full size beam would be a good measure of gain reduction due to the shortening and other losses imposed the traps. In fact, such a beam was modeled, using the same element spacing. The driven element was 27.06' long, and the reflector was 27.7' long. The 15-meter traps were left in their original positions. It is possible that positioning the traps as they might be in a 2-band trap beam could alter the 20-meters values slightly, but the alteration was judged unlikely to be significant.

The maximum front-to-back ratio of the 14.1 MHz beam with 15-meter traps was 10.68 dB, while the feedpoint impedance was 50.5 ohms. Under these control parameters, the forward gain was 5.64 dBi. (Note: for all the 2- element beams modeled here, higher forward gains are certainly possible, but at reduced front-to-back ratios.) The gain difference between the full size Yagi and the version with 15-meter traps is 0.49 dB.


Models of tri-band beams with 3 or more elements and/or more than 2 traps per element will follow the same procedure used here for these simplified models. Data for each trap will be needed for calculations of appropriate parallel R-L-C values. Also need will be a precise element diameter schedule, along with the exact location of the traps. Although time-consuming, such modeling projects should be quite straightforward.

Conclusion

If the technique of modeling traps is sound, then their presence does occasion some loss in forward gain relative to trapless antennas of comparable design, at least for frequencies lower than the resonant trap frequency. How significant this loss may be is a judgment requiring the examination of factors in addition to those included in the modeling exercise. Models also suggest that at frequencies for which the traps represent resonant terminations, gain will be very similar to that of trapless versions of the antenna.

Whatever the gain situation, the exercise does demonstrate that traps can be modeled effectively as parallel R-L-C loads for each frequency of interest.



So, if W4RNL is correct, and he quite often was, then trapped multiband beam antennas DO have about 1/2 db of Loss.
The question then becomes, how much, and what kinds of penalties does one have to pay, in a non trapped multiband beam antenna, for the electrical interaction between all those full sized elements.
Does Gain, Bandwidth, or Rejection (pattern) suffer, in a non trap multiband yagi, and if so, how much ?

Then, we have increased size (longer elements) and windload in the full size non trapped and interlaced multiband Yagi.

I think what CAN be safely said, in all of this, is that any Triband Yagi, trapped or full size non trapped, is a compromise antenna, vs a full size Monoband Yagi, of equivalent boom length.

Good Post Jonathan.
It seems every Ham has their own opinions on how damaging, or not,
 Traps really are, as far as loss goes.
I have to admire the excellent sales job done by Force 12, supporting their design approach (No Traps). LOL, they really "put the fear of God" in many Hams about the loss "inherent in a triband beam" that uses traps.
I have only been a Ham for 27 years, a short time, compared to many.
But I never recalled any of us Hams being worried, as some are now, about Trap Loss.
All our triband yagi antennas had traps, and we pretty much accepted it.

Putting aside the loss question about the use of traps in a triband beam, lets look for a minute at what happens if we choose not to use traps.
WE get more windload for one, because of all the extra elements. Then, the full size elements are considerably longer, important to some of us on small city lots.
Then, there is the automatic interaction we get, by having several different antennas, all on the same boom, in an interlaced design.
How MUCH interaction, and it's effect on performance, is beyond my limited technical capability. We will have to ask some really smart Antenna Elmers, like W8JI, etc, etc.
I understand that with careful computer modeling, this interaction can be minimised, but never completely eliminated.

It sort of surprised me, that none of the trapped tribander antenna makers like Mosley, Hy Gain, or Cush Craft, confronted all the possibly misleading claims of Force 12, and the other Non Trap Triband Beam makers.

You know what they say ? Tell a big enough Lie often enough, and with no counter argument, it becomes "Truth" !

Steve, These Mosley Vertical Antennas http://www.mosley-electronics.com/pages/series/rv.htm#rv6c really get my goat, if you know what I mean ? I hope I did the link right on this Forum ?

As you are probably well aware of, there seem to be several "Mosley Haters" in our ranks, ever since the Champion Radio tests. I am not one of them.
But Steve, have you ever checked out the PRICES Mosley wants for these things ?
These Mosley Trap Verticals cost nearly 4 Times as much as a Hustler or a Butternut!
WTF ?

Then, to further tick me off, Mosley tell us a full, or any kind of radial system is "not required"
Again, WTF 

LOL, u are 2 funny!
Hey, one day I saw a contester bragging about his new Force 12 Tribander!
I knew he used to have a Hy Gain TH 7.
I asked him if he really thought the Force 12 was better ?
He told me the Force 12 was more "amplifier friendly"
IOW, it would easily accept the output from his 3 hole 8877 Amp more better.

I owned them both, and got the Butternut first. It actually scared the little boy next door, and made him Cry, every time he saw it!
So, I went for the Hustler. Over the same radial field, I did not notice any difference at all. The Hustler costs less, and is less of a contraption. It also has the cool DX Engineering Radial Plates for it. Either way, I think u will be happy, as long as u get a good radial field under them.

Yes, but they certainly have more gain then then the interlaced 2 element Force 12 antenna being touted in this thread by a Ham as being "better" then a Hy Gain TH 7.
I have zero "problems" with the Force 12 triband antennas.
Their full sized, interlaced, non trapped elements, are one design approach to making a triband beam antenna.
But, to think that traps have so much loss, that a trapless 2 element Force 12 tribander, can equal, or even approach a trapped Hy Gain TH 6 or a Hy Gain TH 7  IMHO is mental masturbation.
The Bigger Hy Gain Thunderbirds will tear the little Force 12's a new azz, in the pileups.

Now, IF you want to compare a 2 element trapless Force 12 tribander against a smaller 3 element trapped Cush Craft A3 or Hy Gain TH 3, you MIGHT have a case.
I say MIGHT, because if you are a 2 element trapless Force 12 owner, you are still up against 3 Elements vs 2, if you compare your antennas against a CushCraft A3, or a Hy Gain TH 3.
So, the QUESTION is this - Can a 2 element non trapped, interlaced full size tribander, compete with a 3 element trapped tribander ?

Next time, try reading the whole thread ?

There are hundreds of Hams using the 4 element Sirio "CB Beam" on 10 Meters, with great results!
The 4 element Sirio "CB Beam" was designed for the middle of the 11 meter band. (CB Channel 20)
That is 27.205 mhz
You simply take 27.205 and divide it into 28.5, and you will get a number like .97 percent.
Then, take that ratio, and multiply all spacings and element lengths by it, to get the new dimensions for the 10 meter band.