View Full Version : Wa2nan - True-talk 102' G5rv Antenna
N7SGM
07-07-2008, 03:30 PM
I have a few questions about the WA2NAN True-Talk 102' G5RV antenna. I have a Kenwood TS-450SAT and am wondering if the radio's built-in antenna tuner will work for this antenna? I would mount it about 40' high as an inverted "V" in a North/South manner. Also, would the steel mast have a bad effect on the antenna? I would like to operate on 80, 40, and 20 meters. Thanks very much!!
Best 73's
Bob
I can't answer your question about the auto-tuner, as I have no experience with it, but as for the steel mast; no, there should be no adverse effect! Hams and commercial SWBC sites have been using steel masts and towers for antenna supports for years!
In fact, half slopers use the mast as part of the radiating system, and of course, there are always verticals which used the tower AS the radiator !
String it up and enjoy! If your auto-tuner will not match all the frequencies, get an external tuner with additional matching range. You might want to consider getting a balanced tuner and feeding the antenna as a convention balance-fed doublet rather than a "G5RV" design. You will probably find that it works much better that way !
73, Jim
The ladder line needs to be kept a few inches away from the steel mast.
You internal tuner might be able to match the G5RV, and it might not. No way to tell until you try it. The internal tuner on my IC-746Pro matched my G5RV on all bands from 160m to 6m.
G0GQK
07-07-2008, 09:21 PM
To answer your question, No. The tuners in tranceivers are to be regarded as trimmers, if an antenna is almost resonant at the frequency you wish to use then the in- built tuner will do it. A G5RV requires an external ATU and very often these will not allow the use of 15 metres and sometimes 10 metres.
G0GQK
K1FBI
10-06-2008, 07:27 PM
My WA2NAN 102 ft G5RV tunes perfect on 15 meters as a flat-top. 40 meters is 2:1 without a tuner and 20 Meters is 3:1 without a tuner and the same for 80 Meters. Don't even think about 10 Meters it's at least 5-6 S units down from my AR-10 Vert.
My USED TS440s Came with the built-in Tuner but it does not have much range but I never use my antennas out of the bands I designed them for anyway. Well....I used my 160 M dipole for 60 M a few timesw but it was only about 2.5:1 and the tuner did handle that mismatch ok.
WA8RTI
10-07-2008, 01:26 PM
I can't say for your Kenwood, but my ICOM 746 Pro tuner had no problem finding a match 80 to 10 meters with my homebrew 102' G5RV.
W5DXP
10-07-2008, 01:40 PM
My WA2NAN 102 ft G5RV tunes perfect on 15 meters as a flat-top.
If you install an SWR meter between the tuner and the G5RV to measure the actual SWR on the coax, you might change your mind. EZNEC says the SWR is 30:1 resulting in 6.7 dB loss in 80 feet of RG-8x used on 15m. That's about 80% of your power wasted heating the coax on 15m. A G5RV is NOT a good 15m antenna. Probably the only reason your autotuner can match it is because the transmission line is acting as a dummy load.
If you install an SWR meter between the tuner and the G5RV to measure the actual SWR on the coax, you might change your mind. EZNEC says the SWR is 30:1 resulting in 6.7 dB loss in 80 feet of RG-8x used on 15m. That's about 80% of your power wasted heating the coax on 15m. A G5RV is NOT a good 15m antenna. Probably the only reason your autotuner can match it is because the transmission line is acting as a dummy load.
Additionally:
The G5RV was meant by design to be a 3/2w 20M antenna.
Mine is a 102' version and is fed with 450-ohm "window line". It'll cover the lower end of 20M with a VSWR of less than 1.4:1.
If your particular full-size G5RV will not resonate with a fairly "close" match on 20M, something's amiss with its feedline...and as 'DXP points out, the coax is likely being used as a dummy load.
W7WAC
10-07-2008, 05:38 PM
Hello,
I have the 204' version and with a Yaesu 920 driving and think it best to use a external tuner, but to be honest I have never tried it with just the radio tuner. Also I would strongly advise contacting Kerry, the builder of the True- Talk, he is very helpful and always willing to listen. Kerry
E-mail Address(es):
kerry@northnet.org
I have my 204' up 55' on a tower and Kerry said to use at least 12 inches stand off for the ladder line.
Great antenna by the way..
Good Luck!
K1FBI
10-13-2008, 08:14 PM
If you install an SWR meter between the tuner and the G5RV to measure the actual SWR on the coax, you might change your mind. EZNEC says the SWR is 30:1 resulting in 6.7 dB loss in 80 feet of RG-8x used on 15m. That's about 80% of your power wasted heating the coax on 15m. A G5RV is NOT a good 15m antenna. Probably the only reason your autotuner can match it is because the transmission line is acting as a dummy load.
10/12/2008, 4:58 UTC, 21.305 MHz, Contact with VP2E Anguilla...1700 miles! I really like my "dummy load"!:)
K1FBI
10-13-2008, 08:31 PM
Additionally:
The G5RV was meant by design to be a 3/2w 20M antenna.
Mine is a 102' version and is fed with 450-ohm "window line". It'll cover the lower end of 20M with a VSWR of less than 1.4:1.
If your particular full-size G5RV will not resonate with a fairly "close" match on 20M, something's amiss with its feedline...and as 'DXP points out, the coax is likely being used as a dummy load.
I trimmed 16 inches off my G5RV after reading your post and SWR is now 1.5 to 1 on 20 meters without my tuner (Palstar AT2K). On 40 meters 1.7 and and 3.875 MHz I have 2.0 to 1 without the tuner. Glad I had today off! Thank you for that advice. As for you supporting the "dummy load" comment; Multiple contacts with 27 Countries and 9 Islands on this "dummy load"! I should do even better with the lower SWR.
K1FBI
11-15-2008, 01:11 PM
21.290 Mhz/13:02 UTC/contact with TM6VG(France)...not bad for 15 Meters on a "Dummy Load".
W5DXP
11-15-2008, 02:08 PM
I trimmed 16 inches off my G5RV after reading your post and SWR is now 1.5 to 1 on 20 meters without my tuner (Palstar AT2K). On 40 meters 1.7 and and 3.875 MHz I have 2.0 to 1 without the tuner.
What is the SWR on 15m without the tuner?
21.290 Mhz/13:02 UTC/contact with TM6VG(France)...not bad for 15 Meters on a "Dummy Load".
The "Dummy Load" remark was meant to imply a dummy load in parallel with the system load, not a dummy load used by itself. Resistors in antenna systems are generally not a good idea and the loss in the RG8x is mimicking a resistor.
If you are running 100 watts on 15m, you may be radiating 20 watts on that G5RV. One can certainly talk all over the world with 20 watts on 15m but wouldn't you rather be radiating 80 watts instead of wasting 80 watts as heat in the RG8x coax?
An internal autotuner is not likely to match an impedance on the 30:1 SWR circle. The coax loss seems to be lowering the 15m SWR at the tuner to a more manageable value. But if you are happy with 20% efficiency, I guess that's all that matters. Just remember you could be radiating 6 dB more power on 15m thus increasing your signal reports by at least an S-unit.
Incidentally, here is a graph of the optimum lengths of twinlead matching sections for a G5RV for all the HF bands. http://www.w5dxp.com/G5RVlen.jpg
You can see the mismatch problem is not as bad on 15m as it is on 30m, 17m, and 10m.
K1FBI
11-17-2008, 05:40 PM
What is the SWR on 15m without the tuner?
The "Dummy Load" remark was meant to imply a dummy load in parallel with the system load, not a dummy load used by itself. Resistors in antenna systems are generally not a good idea and the loss in the RG8x is mimicking a resistor.
If you are running 100 watts on 15m, you may be radiating 20 watts on that G5RV. One can certainly talk all over the world with 20 watts on 15m but wouldn't you rather be radiating 80 watts instead of wasting 80 watts as heat in the RG8x coax?
An internal autotuner is not likely to match an impedance on the 30:1 SWR circle. The coax loss seems to be lowering the 15m SWR at the tuner to a more manageable value. But if you are happy with 20% efficiency, I guess that's all that matters. Just remember you could be radiating 6 dB more power on 15m thus increasing your signal reports by at least an S-unit.
Incidentally, here is a graph of the optimum lengths of twinlead matching sections for a G5RV for all the HF bands. http://www.w5dxp.com/G5RVlen.jpg
You can see the mismatch problem is not as bad on 15m as it is on 30m, 17m, and 10m.
Look at your own chart for 12,15 and 75 Meters..if what you propose is at all true then the antenna design should also be down about 80% of power on 12 and 75 meters. With 4 feet or less wire compared to 20 Meters using your chart, it is highly doubtful. If you want to see someone who actually tested things, look at this link which lines up with my actual results. http://www.w8ji.com/g5rv_facts.htm
73
W5DXP
11-17-2008, 06:35 PM
Look at your own chart for 12,15 and 75 Meters..if what you propose is at all true then the antenna design should also be down about 80% of power on 12 and 75 meters.
On 75m, being off by two feet is equal to less than 1% of a wavelength, i.e. mostly negligible. On 15m, being off by four feet is equal to 9% of a wavelength, i.e. not negligible.
It is entirely possible that the dimensions of your "G5RV" differ from the G5RV design specifications in which case, it may not have 80% loss on 15m. If you will tell me what is your SWR on 15m and what kind of coax you are using, I can be more accurate about your coax losses.
K1FBI
11-18-2008, 10:45 PM
Without the tuner my SWR is 3.2:1 and I can tune 1:1
The coax is 31 FT of HD 300 Ohm window line into 70 FT of RG8X.
Don't forget I trimmed 16" off the total original overall length of the 102 FT antenna section.
Should be interesting. Thanks and 73 K1FBI John.
W5DXP
11-18-2008, 11:49 PM
Without the tuner my SWR is 3.2:1 and I can tune 1:1
The coax is 31 FT of HD 300 Ohm window line into 70 FT of RG8X. Don't forget I trimmed 16" off the total original overall length of the 102 FT antenna section. Should be interesting. Thanks and 73 K1FBI John.
Well, everything is clear now. Your antenna doesn't meet the G5RV specifications as it is now resonant on approximately 14.5 MHz. Your dipole is shorter than 1.5WL on 20m and your parallel matching section is shorter than 1/2WL on 20m. EZNEC says the SWR at the coax/twinlead junction on 15m is now 6:1 instead of the 30:1 reported for the standard G5RV. I also checked 80m, 40m, 20m, and 12m. The changes don't seem to have bothered the performance much on those other bands. Looks like an excellent modification. Congratulations.
K1FBI
11-19-2008, 12:23 AM
Thanks for running those calculations for me Cecil. That is good news.
73, John
You might want to consider getting a balanced tuner and feeding the antenna as a convention balance-fed doublet rather than a "G5RV" design. You will probably find that it works much better that way !
73, Jim
Outstanding advice. Why the so called "G5RV" antennas are so popular is beyond me.
A fan dipole fed with W7FG ladderline and a homebrew balanced tuner was the best investment I ever made to my station.
W5DXP
11-19-2008, 12:49 PM
Outstanding advice. Why the so called "G5RV" antennas are so popular is beyond me.
Would you believe that a 102 foot dipole fed with 300 ohm twinlead all the way to the tuner has more feedline loss on 80m than a G5RV fed with RG-213? The reason is the 20:1 SWR on the twinlead vs the 4:1 SWR on the coax.
KJ4DKT
10-21-2009, 01:16 AM
i hung kerrys true-talk 102 ft as inverted v about 3 mos ago. i have talked all over the world with no more than 100 watts. the metal mast will not affect the performance. it has to be the best made antenna in its class. pay more or pay less but you cant beat it for performance. kerrys product is number one in my opinion. fred
Why go round and round about this?
Those who answered on a technical basis are more correct.
Those who list their contact acomplishments and think it supports something are missing the technical side of the issues. As stated, contacts can often be made as well at 20 watts as at 100 watts, in many cases so what do contacts prove?
How would you know that you could or could not do better on a more correct antenna setup unless you see the technical side and make the changes and do the long term comparisons?
Why not try and understand that on different bands the impedence changes at the antenna terminals and is reflected at the radio termination by the changes in transmission line physics AND that radiation angle changes per band for an antenna at a fixed height.
As for the auto tuner, it depend on the tuner's range. If it sees an impedence within it's range, a match will be found. Dosn't make it correct or really fix anything just a transformation. It dosn't change losses in the system.
Changing the antenna length even by the few inches may be enough to "reflect" an impedence within the tuners range that the antenna would not at it's previous length.
Let me throw somthing else into this mix. I see on the use of my AT and looking at total output power into a matched condition with and without the AT inline, even into a dummy load that the AT may be responsible for as much as a 10 watt loss when in the circuit.
I can match the radio through an external tuner and it's watt meter will always show a 10 watt loss with the AT inline when all is flat matched.
Unless I am missing something, I see this as a lose in the AT.
So add this to an antenna that is not resonant and you lose even more.
The overall impedence the radio sees is a very complex summation of all the points in the system such that one can't just say with any ease, certainty or simplicity what is better or worse and why, unless you look at all the part and see where the largest issues occurr and reduce them with the best compromises.
Would you believe that a 102 foot dipole fed with 300 ohm twinlead all the way to the tuner has more feedline loss on 80m than a G5RV fed with RG-213? The reason is the 20:1 SWR on the twinlead vs the 4:1 SWR on the coax.
Great, but I never used 300 ohm twinlead nor would I recommend it. I use 600 ohm open wire. ANd I have yet to see the G5RV made with RG-213 :D
According to the coax calculator here: http://www.qsl.net/co8tw/Coax%20Calculator.htm the 600 ohm open wire has 1/2 the loss at 20:1 as RG-213 does at 4:1.
W5DXP
10-21-2009, 03:53 PM
Great, but I never used 300 ohm twinlead nor would I recommend it. I use 600 ohm open wire.
Excellent! Please note that my earlier statement was about 300 ohm twinlead, not about 600 ohm open-wire feedline.
Note that simply changing the G5RV's series matching section from 300 ohms to 600 ohms results in a change in coax SWR on 3.8 MHz from 3:1 to 34:1 so that particular modification is not recommended.
Outstanding! That would be of great interest if I ever consider using a G5RV, which is about as likely as me hitting the Powerball jackpot.
I have a few questions about the WA2NAN True-Talk 102' G5RV antenna. I have a Kenwood TS-450SAT and am wondering if the radio's built-in antenna tuner will work for this antenna? I would mount it about 40' high as an inverted "V" in a North/South manner. Also, would the steel mast have a bad effect on the antenna? I would like to operate on 80, 40, and 20 meters. Thanks very much!!
Best 73's
Bob
Do not waste your money spending the extra dollars on the "true talk" antenna. I promise you it will not play better than the $35 mfj 450 ohm version. If you use a steel mast, keep the ladder line a few inches away from the mast!
I use 4' fiberglass mast sections that I found on ebay. They were used by the military to support tents. I have my G5RV supported by these and is 40' up.
Don't get caught up in the "true talk" hype..PLEASE
i hung kerrys true-talk 102 ft as inverted v about 3 mos ago. i have talked all over the world with no more than 100 watts. the metal mast will not affect the performance. it has to be the best made antenna in its class. pay more or pay less but you cant beat it for performance. kerrys product is number one in my opinion. fred
Oh come on! The true talk is junk! cheap construction, no balun! The guy is making money off of the ignorance of others!
Outstanding advice. Why the so called "G5RV" antennas are so popular is beyond me.
A fan dipole fed with W7FG ladderline and a homebrew balanced tuner was the best investment I ever made to my station.
haha, the G5RV is popular because it works well and is a decent multiband compromise. The SWR is acceptable on 15, 20, 40, and 80. I feed mine with 70' of 213, 70' of 213 will not act as a dummy load, lol.
Cecil, I read your comments about 300 ohm twinlead, but I cannot imagine that any true ham would use such poor feedline for ANY ham antenna.
Right now, 400 ohm ladder line is in very scarce supply here in the U.S., and it could be a blessing in disguise ! I can envision many hams building their own open wire feedline to feed their doublet antennas ( I intend to ! ) and I believe we will all be the better for doing so !
That's JMHO, but I think it bears scrutiny !
WN9HJW
10-21-2009, 10:57 PM
i hung kerrys true-talk 102 ft as inverted v about 3 mos ago. i have talked all over the world with no more than 100 watts. the metal mast will not affect the performance. it has to be the best made antenna in its class. pay more or pay less but you cant beat it for performance. kerrys product is number one in my opinion. fred
As has been pointed out, you're not radiating 100 watts and on some bands it may be considerably less than that. You could easily do even better.
My first antenna was a G5RV and I thought, at first, that it was a miracle worker. But then I put up just a plain jane coax-fed half-wave dipole for 40 (3/2 wave on 15 meters) and it was like night and day on 15m compared to the G5RV.
I have the WA2NAN "TrueTalk" G5RV. I have used it with a Kenwood TS-450S
with the internal tuner. It found a good match on 80, 40, 20, and 10 Meters.
For some reason it didn't find a match on 15. It even found a match on most of the WARC Bands.
My recommendation is to install it just as WA2NAN says to install it. Don't make the Inverted "V" too steep an angle. I wound a choke Balun with the coax right at the bottom of the 300-Ohm ladder line, before the coax entered the shack. Remaining coax is wound up on the floor of the shack.
I have been very satisfied with the G5RV and get good reports. WA2NAN makes a good antenna. 73 and Good DX de KJ9R, Joe.;);)
