HFU HF Underground
Technical Topics => Equipment => Topic started by: ChrisSmolinski on March 25, 2008, 0011 UTC
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Has anyone here used one? I've been thinking of setting one up, to supplement my assortment of dipoles for each band.
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George Maroti uses one and told me he likes it. He might be the man to contact on this one.
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I have an RF-Systems T2FD that I've used off & on. It was my main antenna back in 2000 & as recently in 2006 until I switched to the EWE. It was a great performer overall, but I wasn't satisfied with the high angle rejection & needed something a little more directional. It did make for a great one-stop-shop setup for the HF spectrum as a whole. If I was forced to choose only one antenna for all applications & band segments, it would be the one.
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A few weeks ago, I finally put up my T2FD. I went with one 131.5 ft long, so cut for 2500 kHz and up. I'm using a 12:1 balun and feeding it with 100 ft of RG6-U 75 ohm coax. The center termination resistor is 800 ohms.
The high end is perhaps 50 ft up, the low end about 20 ft, and it slopes to the south. Not my preferred orientation, but you take what the trees give you.
I'm really amazed with the reception. While the signal is generally an S unit or two lower than that from one of my dedicated dipoles (for the 90, 60, 48 and 43 meter bands), the noise is much less, hence a much better signal to noise ratio. And it works everywhere on HF, I don't need to keep flipping between antennas.
Performance on the high end of the MW band is also excellent (as compared to an approximately 500 ft long random wire). Performance is much worse on the low end, as expected.
I'm really pleased with the results. I'm actually very close to removing the antennas switch, and just connecting this as my only antenna. It's that good.
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Between these reports from Jon-FL, Chris, Sealord and others I've chattered with online, the T2FD sounds like a winner. I've compared audio clips from Jon-FL, Sealord and other folks in the Florida area, and am continually impressed with the low static levels compared with designs other than the T2FD and Sealord's ewe.
Funny, when I bought my copy of Joe Carr's receiving antenna handbook many years ago the original G.L. Countryman design from which the T2FD was derived was rather lightly regarded and dismissed by some folks as either obsolete or too much of a compromise. Supposedly it was popular on military installations but I wasn't into radio back in the '70s and didn't pay attention to the radio setups on the various bases where I was stationed.
I have a huge back yard at my apartment complex that's virtually unused. Hmm... I wonder how well a T2FD would work with a 100-yard run of coax feedline, which is the closest I could get to the property border?
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Since coax loss at HF is typically very low, I don't see a 100 yard run causing major problems. 100 yards of RG-8 results in a 3 dB loss - half an S unit. Even crappy RG-58 only doubles that to 6 dB, and RG-58 isn't really even coax ;-)
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Even crappy RG-58 only doubles that to 6 dB, and RG-58 isn't really even coax ;-)
You mean that stereo patch cable that CB good buddies instist is for RF? :D ;D
Peace!
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Even crappy RG-58 only doubles that to 6 dB, and RG-58 isn't really even coax ;-)
You mean that stereo patch cable that CB good buddies instist is for RF? :D ;D
Peace!
LMAO!!!
A good 75% percent of my tx'es over the years have been made with antennas consisting of nothing but Dollar Store speaker wire for feedline and antenna. They cost less than two bucks and when the feedline gets so twisted it's not working well,I split it for the next antenna's legs and buy another 100 feet of the same stuff. The stuff is actually lower loss than RG-58.
With a third hand tuner I've been heard across most off North America for the better part of a decade on 10-14 watts of AM and close-out wire. LOL!!!
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LMAO!!!
A good 75% percent of my tx'es over the years have been made with antennas consisting of nothing but Dollar Store speaker wire for feedline and antenna. They cost less than two bucks and when the feedline gets so twisted it's not working well,I split it for the next antenna's legs and buy another 100 feet of the same stuff. The stuff is actually lower loss than RG-58.
With a third hand tuner I've been heard across most off North America for the better part of a decade on 10-14 watts of AM and close-out wire. LOL!!!
Ahh... you've been using ladder line!
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He made it audiophile grade for better modulation - he can sell the dollar store wire now for $50/metre ;D
Peace!
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You're not far off,I've actually had one stolen since the price of copper has gone up. I left it up a tree for later use,when I came back it was gone.
One of the things that separates FM pirates from SW pirates,IMO,is the cheapness on the SW side. A FM pirate will put together a twenty-thirty thousand dollar studio for a 1-5 watt station. Most SW pirates wouldn't spend hard cash on studio equipment if they had money in piles. They're down at the pawn shops and thrift stores wrestlin' the staff for half off on a beat-up mixer or trying to get that fifty cent twenty year old Walkman for a nickle.
It's that ol' hamfest mentality the SW guys come out of.
Glad the antenna worked out for you Chris. I don't have that kind of room but I may try a smaller version. I've got favorable trees towards W.Europe. I could use the thing for listening to Euro-pirates.
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You're not far off,I've actually had one stolen since the price of copper has gone up. I left it up a tree for later use,when I came back it was gone.
Oh geez!
I wonder if they read today's Report on Business, where copper took its biggest single day loss ever!
They might do better stealing aluminum.
One of the things that separates FM pirates from SW pirates,IMO,is the cheapness on the SW side. A FM pirate will put together a twenty-thirty thousand dollar studio for a 1-5 watt station. Most SW pirates wouldn't spend hard cash on studio equipment if they had money in piles. They're down at the pawn shops and thrift stores wrestlin' the staff for half off on a beat-up mixer or trying to get that fifty cent twenty year old Walkman for a nickle.
It's that ol' hamfest mentality the SW guys come out of.
I can't really argue there.
They key to great audio is the studio and processing equipment. If one doesn't put any effort into purchasing or designing the multi-band compressor/limiter, even more so for the amplitude modulation modes, they should stay away from the hobby.
Can always pick out the AM pirate - crappy audio. Or it could just be Radio Cairo ;D
Peace!
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A friend told me the Corps of Engineers used the B&W version of the
T2FD at a few sites and wasn't impressed with performance. Basically your trading bandwidth for performance since the far ends of the antenna wires terminates in a high value dummy load to lower the SWR. in these times of low solar activity (naming the few sunspots and all ;D ) antenna performance (or lack there of) is more evident. at the peak of the cycle a wet string draped across your shack can get you around the world.
When reading reviews of antennas, like on eHam, ALWAYS notice the date and correlate it to the solar cycle.
.
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There's no doubt that signal levels are lower with the T2FD than a dipole cut for the given band (i still have several dipoles to compare to). But, the overall signal to noise ratio is superior with the T2FD vs any of my single band dipoles (all of which are fed with coax to a balun).
YMMV, and I only receive, I don't transmit.
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...and I only receive, I don't transmit.
:o
You were my hero :(
LOL! :D
Peace!
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"W7LPN thanks for your Emails:
Trust me, I've read them all.... Even ole Marty Jue..(XXX) notes of distain:...
The problem now is, all the advertisers who pay big buck$ with XXX, & XX mags to advertise their Antenna tuners have now threatened the ARRL/QST, and CQ to redraw or reduce their advertising if they continue to publish articles about T2FD, and WINDOM (tunerless) antennas. ANY Antenna that does not use an antenna tuner that could be written about in these pubs are bad news for the leading Amateur Publications. Cebik is now SK, but back when he wrote that piece, he was writing books for QST/ARRL.
For eighteen years, I was the digital editor of XX magazine, never missed a month writing my column.. sometimes several... Then when I wrote an article about the T2FD, they refused to print it... then I wrote an article about the Windom.... suddenly I had some sort of writers disease... they would not print it either.
I was furious, as I had put a lot of time and effort into those articles (column).
I gave them my "notice" and immediately stopped writing for them. They got P/O'd and then one of the employees of XX (nameless), called and informed me WHY they would not print my articles about the antennas that did not need an Antenna Tuner....
Seems two of their biggest advertisers threatened to pull all their advertising dollars if they ever gave credence to any article(s) that took away antenna tuner sales.
It's a sad day when politics enters our hobby, and begin to dictate editorial policy… and the rank-n-file HAM suffers because of the all-mighty dollar.
Up until 1995, all the handbooks, HAM magazines, and league publications (Antenna Books) had articles about T2FD, Windoms and specific antennas that did not require an antenna tuner.
SUDDENLY, all the Antenna handbooks, Annual Amateur Radio Handbooks.. and publications sold by the XXXX, XXX, or XX, took a noticeable difference in their hobby antenna related content and antenna information:!
ALL, I mean ALL reference to the T2FD, the Windom, and tunerLESS antennas was noticeably missing from these rags!
Here be side me, in my BOOK CASE are the last 4 years of ARRL Annual Handbooks. Not a word about these antennas.
Add to that, I have the ARRL Classic Wire type Antenna Handbook; first Edition Copyright 1999 through 2009.
Here is a book that should be bulging with T2FD, Windom and other WIRE type antennas (that don’t need antenna tuners), alas… NOTHING!
I tried to make a big noise, but I was laughed at because I related this to some of the "powers-that-be" at the league, and XX.... they poo poo'd it and denied it no less.
I rest my case.
Now you understand why I don't advertise in any of these “Hobby Rags.”
Every chance they get, they'll have some of their cronies put something on an antanna review page in print, trying to discredit me. I'm still here, and most of them are out to pasture.
AND now’ you know "The rest of the story !"
Have a great weekend."
Anonymous, but not too hard to tell who it is.
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Politics ::)
Peace!
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I have 2 of the B&W folded dipoles (T2FD type). They both work much better than standard dipoles. Out of the dozen or so antennas here, the folded dipoles are the 'go to' antennas most of the time.
Gee whiz, the local FCC office has one on their roof for their HF intercept! They can't be THAT bad. I agree with the author, if every ham and SWL tried a commercially built T2FD style antenna, tuner sales would certainly drop drastically. I don't buy into the conspiracy theory, but it is possible I suppose.
One of my folded dipoles is about 9 years old, the other about 3. The first was installed N/S and was just such an awesome performer, I couldn't resist buying the second one when I was able to install E/W. Not a bit sorry about either purchase. Would certainly buy again.
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Thank you for an honest real-time evaluation. I don't really care about whether anyone believes these antennas(T2FD & Windom) have been conspired against. I'm sure if I was the manufacturer and couldn't get a fair deal I would feel very different about it. If you occasionally get on QRZ forum look up antennas, limited space W7LPN thread. The so called experts have been bashing the t2fd for a few days. I'm relatively sure these "Experts" don't, nor ever have, owned a commercially manufactured T2FD. The truth as you have stated it needs to be known.
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That's exactly why I stay off of QRZ forums and other similar forums. You stand a better chance talking reason into a CB forum than you do the ham ones. Hams hear someone say something like "RG-8 is the best coax on the planet" and then they parrot that from that day forward. They don't know, they have never done their own experiments, and 99.9% of them don't have the right test gear to do it right anyway. Heck, 99.9% of them say "I put 1000 watts in, I get 999 watts out" and call it good. What about receive? What about induced noise? What about efficient transfer of those precious few microvolts from the antenna to the receiver? A 2-way conversation requires both stations to be able to copy each other!
The hams are all 'experts' because they have a license. Big whoop. If I have a driver's license, does that automatically make me an expert driver? No, of course not. Same thing.
I happen to be a 'real' RF engineer, and have been a radio and TV Chief Engineer for 30 years. I find it amusing that a ham with no engineering education or background will argue a basic point with me. I have actually had hams with Extra licenses tell me they know more than me simply because I have not upgraded from General. Seriously! In an effort to keep my blood pressure low, I avoid those ridiculous forums. All hambones can disappear forever as far as I'm concerned sometimes. 90% of hams really repulse me. I suggest you adopt the same policy, life is so much more peaceful when you avoid the hambones.
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By the way... I just read your thread on QRZ. The two 'experts' that replied are showing their lack of knowledge, and a sharp prejudice for something they have not tried themselves.
If they had a shred of knowledge in this department, they would know that a balancing resistor on the OPPOSITE side of a folded dipole does not absorb "half the transmitter power" at all. If that were true, that resistor would blow up every time I run 1500 watts on CW. In fact, at most, the resistor will absorb 1/4 of the transmitter power if the antenna is that far out of resonance on my chosen operating frequency. The other 3/4 is radiated with a very small amount coming back (<10%). Most of the time, the balancing resistor isn't doing very much.
And, none of those jerkoffs even considered the receiving characteristics of the antenna (which is what it was actually designed for). The balancing resistor keeps the elements in perfect balance all the time in relation to the feedpoint, and THAT does a very effective job of canceling out local noise. In addition, at MOST, the balancing resistor might cause a 3 dB drop in signal (1/2 an S-unit). Most of the time, it absorbs little, if any signal. Almost all signal is fed to the feedpoint through the folded dipoles because of the slightly lower resistance at the feedpoint that at the balance point. That is why for a 500 ohm feedpoint, you use a 540 to 600 ohm resistor in a terminated folded dipole.
I could go on and on, but I have a job, and a life. Those 'expert' pinheads need one of each too.
See? Hams really jerk my chain!
73, TS
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About the only thing I keep my (extra) license active for these days is to keep people from grousing about the legality of my data and video links. Enough hams can't cope with the idea that someone one third their age is allowed to play with "their" radio waves, or just might actually know something about RF that it almost isn't worth even listening around the bands anymore, let alone transmitting. If you can manage to find someone who doesn't go on about how you "can't be a REAL ham because...", then about all that's left for them to talk about is their medical problems. Beyond that, it's "call, signal report (always an inaccurate 5x9), weather, 73".
Just last week, one of the local FM repeaters was all abuzz with people offering their valuable opinions on which coax a new ham should use to hook up his 2-meter ground plane. One of the "experts" - I know he was an expert because he mentioned several times that he's been a ham for almost fifty years now - repeatedly told him that you didn't need to worry about coax line loss. It was unimportant, he said, because as an example, he's got 10 or 12 dB loss on his antenna, and "you can't hardly even hear a twelve dB sound if you're tryin'". Even so, he said that he just makes up for it by talking louder into the mic, and everyone can hear him just fine (his audio was clipping pretty badly, actually). The saddest part was, NOBODY contradicted him; several even agreed wholeheartedly.
Other "wisdom" I have heard discussed on the radio recently:- RF radiation and ionizing radiation are the same thing (because they're both called "radiation", you know).
- There's no difference between the different types of coax - it's all just price.
- SWR doesn't matter with modern radios - they can pump full power into any kind of antenna (no mention of automatic power reduction when high SWR is encountered).
- You've GOT to have an SWR of 1.1 or less in all cases, or you'll burn up your finals within minutes.
- You can't use a computer and a radio together because they'll blow each other up.
- You can't build your own antennas or radio gear, because the people who make commercial units have access to "special wire", materials, and "design computers" to make them work.
- Regular horizontally-strung dipoles are non-directional (all cases, regardless of frequency or height above ground).
- It's impossible to operate HF from a moving vehicle, because the motion will cancel out the longer wavelengths.
- You can't polarize an FM signal (apparently, horizontal, vertical, RH and LH circular polarization are all just a bunch of hooey, despite demonstrable effect).
- The one biggest thing that can make or break a hamfest is having enough electric scooter carts available for rent (out of all of the above, this is the one item I believe to be true).
Listening to the local repeaters can be hilarious at times, but it doesn't take long before it just becomes too depressing to bear anymore; my dual-band mobiles are most often used for listening to the local EMT dispatchers these days.
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Thanks again. I am not an RF engineer. I know a few of them & they make more sense than any of these "Hambones" you speak of. When he was criticizing the effects of the non-terminating resistor, it sounded like puffed up BS. Sooner or later you can recognize the truth and the level heads in a discussion. Tahnks , & 73.
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First of all, Seamus- You literally had me laughing out loud! I actually spit on my screen when I read the part about the electric scooters! Man, that was funny.
W7LPN- Yes, you are correct. It is pretty easy to spot the 'real' experts sometimes.
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I'm searching for the truth. Please read. :)
W8JI
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Join Date: Oct 2003
Posts: 2,853
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Any one additional comment you can pass back to "tube shortwave" about this:
"If they had a shred of knowledge in this department, they would know that a balancing resistor on the OPPOSITE side of a folded dipole does not absorb "half the transmitter power" at all. "
That wasn't the statement at all. He isn't even honest enough to quote someone accurately.
The statement I made (it is in black and white here on the Zed, so there is no debating he misquoted) is the resistor sometimes dissipates less than half of the power applied to the T2FD antenna, and on other bands it dissipates much more than half the applied power. Nothing worse than a critic who fabricates the very statements he is openly critical of.
He goes on to say:
"If that were true, that resistor would blow up every time I run 1500 watts on CW. In fact, at most, the resistor will absorb 1/4 of the transmitter power if the antenna is that far out of resonance on my chosen operating frequency. The other 3/4 is radiated with a very small amount coming back (<10%). Most of the time, the balancing resistor isn't doing very much."
That's clearly wrong, as any analysis or measurement has shown. What "tube shortwave" is unaware of is the owner of Amp Supply found that antenna design in some publication and decided to build it commercially. I believe he eventually cooked up a deal with B&W to buy the "design" of that, and a terminated V, antenna. The original matching transformers were the filament chokes from amplifiers, wound at Prime Instruments.
I actually directly measured the dissipation in the resistor and it was pretty high overall.
There is considerable mutual coupling between the dipole half with the resistor, and the dipole half with the feedline. Anyone who knows anything about antennas understands mutual coupling of two very long wires (90 feet or so long) spaced a few inches apart is extremely high, plus the ends of the wires are directly connected. The resistor is, for nearly all practical purposes, directly connected across the feedline.
The power division depends largely upon the unterminated impedance at the feedpoint. On bands where the antenna is a conventional half-wave or 3/4 wave dipole length, that impedance is low and the resistor has limited effect on the system. On bands where the feedpoint would have a high unterminated impedance, the resistor soaks up most of the energy.
This is why the SWR stabilizes. What would be a terrible SWR on some bands is reduced by diverting energy into the resistor on those bands.
When testing the antenna as a consultant doing work at Amp Supply, I built an antenna at home and ran the "resistor" side through ladder line to a dummy load. I had an RF current meter in series with the load, and measured load current. I still have the huge resistor I used here, I use it as a dummy load for testing high impedance balanced systems. The measured result was basically as LB Cebik and many others have analyzed and published.
If you search the web you will find many articles telling exactly what the T2FD antenna is, and what it is not.
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I bought it! Thanks guys. I saw no reason so many positive reviews(unsolicited w/o monetary gain) would exaggerate or lie about favorable antenna performance. I think Buck called it right. http://www.buxcomm.com/catalog/index.php?main_page=product_info&cPath=45&products_id=2184&zenid=qj0ragan0h62c260r6lvhbbsf3
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Well, thank you for sharing. However, I am not about to engage in an argument across boards with someone.
Just FYI (for you, not him)- You cannot compare real field and design experience with a guy who just repeats what other people write and calls it 'fact'. Perhaps his non-resonant antenna was being influenced by outside objects or too low to the ground. Or, perhaps his lab conditions were less than ideal for a non-prejudiced outcome.
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I agree completely. Some folks quote technical mumbo-jumbo and have never used the antenna to which they are criticizing. Buck Has one up & has used it for years. The only reason for posting quotes is to sift through the garbage & get to the facts, which I believe I've done. That's why I went ahead and purchased this antenna. I'll know for myself within a couple weeks whether it will operate as advetised here at my QTH. I understand good earth, poor earth, salt water, grounding & reflection, so I'm no ostrich. I will understand some or most of the why's or why not's.
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Well, it will be very nice to hear how it works for you.
You just have to love hams that think they are SO much smarter than us actual RF engineers. It's kinda cute.
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A fellow ham friend is an ex-military, then commercial RF engineer for 40-50 years, and I trust his judgment implicitly. He doesn't have to prove a thing, has been on the local ham clubs board of directors, or a welcome guest at tech meetings for decades. working at a career for 8+ hours a day for nearly 50 years trumps a test you can take 100 times, on line, to practice the right answers, while comprehending nothing, every time in my book.
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Those guys can bite me! I received it today, put it up in a hurry. 40m from Boise to Tacoma to Joe with a 60ft vertical with 600watts, I'm barefoot with 100 watts , we both are 5/9!!!
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Excellent, OM.
Now, go to the ham board and tell all the 'experts'- "Told you so!".
Then, they will fill 5 more pages with how much of your transmitter power is turning into heat, how foolish you are for choosing that antenna, how much better your signal 'would have been' if you had used blah, blah, blah...
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I'm actually going to collect more information first so they can't claim 40m is the only band my antenna will Tx on. :P
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Actually I'm gonna rip them a new one! I've been hitting DX on 10m, & 20m, lots of 600-1800 mile chat on 40m, and my nightly net check-ins on 75m west coast. This IS A QUIET ANTENNA, and a Good performer, matching at least equal to all barefoot incoming signals and equal to one pushing 600 watts.
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Good!