Broadband HF Dipoles In Use By FLEX-6000 Owners ?

Paul, WB5AGF

With The FLEX-6000 Radios having the ability to simultaneously display virtually the entire HF spectrum it would seem desirable to have an antenna which provides a reasonable impedance match over the entire range (without frequency sensitive tuning).

(In my situation a basic dipole or vertical antenna are the only reasonable choices so I am restricting my considerations to those types.)

I have some knowledge of the literature covering the resistively terminated antenna types popularized over the past 30 - 50 years but would appreciate feedback from actual users of these antennas. (I'm aware of the 'fan-dipole' broadbanding technique but don't believe that it's practical in my situation.)

The two dipole style resistively terminated antennas that immediately come-to-mind are the folded-dipole (both 2 and 3 wire) and the 'Australian Dipole' (the first I heard of it was years ago in 'Ham Radio' when Bill Orr, W6SAI, mentioned it in his column).

Just today I came across a reference to the 'Robinson-Barnes HF Broadband Antenna' but when I go to the manufacturer's Web Site (Bushcomm HF Antennas in Bayswater, Western Australia) their folded-dipole style antennas (they make some other types) look to me like terminated folded-dipoles (they use stainless-steel for the antenna wires and I'm reminded of the old Barker & Williamson broadband terminated folded-dipole of years past) and not something 'different'.

Are there members who have experience with resistively terminated dipole type antennas ? If so I'd like to hear from you - your experiences and opinions.

Thanks;

Paul, WB5AGF

ctate243

Paul I spoke briefly with Gerald in Visalia on the the issue regarding Flex friendly antennas that would truly allow broad banded slice availlability and performance for the Flex.  The most amazing of radios are only as good as their antennas. This could be an important topic for the brain trust.   My first thoughts revolve around Log Periodic beams...  And a search for a lightweight one would probably be worth checking out.  That being the issue, they are heavy (logs of aluminum) and expensive.

kr4k

I operate three of the Bushcomm antennas with the 6700:
BBA-100Ce
BBA-600Ve
BBA-1kDe

I use it on ham, MARS, and WH2XOO experimental license frequencies, 2.2 MHz to 27 MHz. I also operate these on 160M because they are the long versions.

The antennas often get reports "best signal on the band".

Have had one of the Bushcomm antennas up for 11 years. The only notice of weathering is on the fiberglass spreaders, and those are only a little fuzzy.

The Robinson-Barnes HF Broadband Antenna is a terminated 3-wire antenna. For details on the theory and NEC modeling results, recommend Cebik's article "Notes on Wide-band Multi-Wire Folded-Dipoles".

Array Solutions used to sell a similar antenna:
http://www.arraysolutions.com/Products/AS-BB-XXSeries.htm

There are other commercial versions of the RB 3-wire:
http://www.moonraker.com.au/#!hf-antennas/c1byd
http://www.lencom.com.au/index.php/products/hf-base-antennas/3-wire-folded-dipole-antennas

Have used the B&W two-wire versions, and the Bushcomm antennas are much better.

73/gus  KR4K

ctate243

BTW I experimented on those resistive terminated folded dipoles many years ago when I was just starting out.  They work ok on the upper bands..  the have low SWR on the low bands but so does a dummy load.. and these are pretty close to that.    

kr4k

Can recommend the Tennadyne T8 as an excellent HLPA for use with the 6700.

73/gus

ctate243

Thats a mighty looking beast but I am sure it works great.

EA4GLI

Have you considered a HexBeam?

kr4k

I have documented that the Bushcomm antennas perform just as Cebik describes in his article. The low frequency knee on mine is about 100 kHz lower than he predicted. I have the center up 48 ft. with ends at about 30 ft.

These antennas are not dummy loads - any more than many claim of HLPA antennas vs yagi antennas.  If you need a broadband HF antenna without a tuner, I can recommend the 3-wire RB antennas after many years use.

73/gus
Dr. Gus Lott, KR4K

ctate243

another choice on my short list perhaps for a residential station.  At my hilltop contest station a hex beam may last an afternoon or so before it becomes one with the hill..  

ctate243

Hi Gus.  I agree that they definitely work..but performance is definitely relative.

 I think the one I worked with was a B & W and in fact I am aware they use these in some military applications.. or at least used to.  Not for everyone however.  My requirements are a bit less modest at a competitive station at 2000 ft, it needs to be rotatable,  handle 120 mph winds, have measurable gain and handle full legal limit power.

Barry Kanne

Hi Paul:

I have been using a B&W folded dipole, model BWD-90, that covers down to 160 meters.  It has supported my 3000 and now my 6500 with excellent results.  It is no longer available via normal ham channels as B&W have seemed to drop out of the amateur market in favor of the much higher priced government market.  But, if you come across one, I am sure you will enjoy its performance.

Mine is strung between 2 tall pine trees with a heavy duty screen door spring on each end where the support cable (aircraft cable) is connected to the tree trunk.  That way as the trees sway in a wind, the antenna remains protected against undue strain and the springs take up the slack.

I also have a 4 element beam for 10-20 and appreciate the additional gain it provides, but for general use, the folded dipole is my primary antenna.

73,
Barry in Atlanta

Dale KB5VE

I have run a Tenadyne t6 and it is unreal with the pan adapter on the 6000 series, I talked to a ham running a 6500 with a cobra antenna,

Steve N4LQ

This version is interesting. Read toward the bottom. He claims a length of 122' instead of the usual 90' puts the low current point at the resistor on harmonic related bands. Interesting. 
http://www.b-squareengineering.com/TerminatedFoldedDipole.htm

73 Steve N4LQ --- Tilted but not Terminated

Steve N4LQ

Gus
How is the 3rd wire connected? 

k3Tim

Good find Steve!   Their comments seem to be spot-on.  

I had a B&W TFT long ago and it seemed to do fine under certain conditions.  Mine wasn't at the proper height.

Tim

kr4k

Above is from Cebik's article. I add the Bushcomm OFO kit which allows you to place the BALUN at the ground. The OFO kit also significantly improves NVIS performance.

My BBA-100Ce antenna have been through at least two severe thunderstorms where winds exceeded 80 mph, toppling about 18 oak trees, and a hail storm that totaled our Airstream trailer. They are commercial grade, wind rated to 130 mph, and are built like tanks - just like the 6700 design!

Recommend reading the eHam.com reviews and Cebik's article.

The Bushcomm RB antennas and the Tennadyne T8 HLPA make using the 6700 so easy, allowing for excellent broad spectrum pan adapter views. They simplify remote 6700 operation, and antennas like this add 6700 use options like ALE and broadband waveforms. For my 6700 use, they are worth the small performance degradation compared to a dipole.

KD8TVB

I run an inverted V OCF dipole for 10-80M, center is at 30 ft, ends at 9 ft... amazed how well this antenna works

Ken - NM9P

I also run a home built Offset Fed Dipole, cut for 160 Meters.... About 90 ft. on the short leg and about 180 ft. on the long leg. Use a good 4:1 current balance at the center. Elevation is about 38 ft. at the feed point, and about 18 ft. on the ends with two left-hand bends on the long end to make it fit my yard. It works well on all bands except 15 meters. I still use the tuner to tweak it.

Roger Rockwell/na4rr

How about  the broadband hexagonal beam as designed by G3TXQ.  ( http://www.karinya.net/g3txq/hexbeam/broadband/ ). and shameless plug for the one I’ve been building and selling for about three years.  This is my main antenna for 6m-20m.  I usually have panadapters open on 6,m 10, and 17.  I have become one of those 6m freaks and that is where I prefer to be.  You never know when the band is going to open or from what direction.  The hex is plenty good enough to keep an eye on the band.  When it shows some promise I switch over to the 6 element quad.  I have it on a 50ft tilt over crank-up tower.  It is at 25ft 99% of the time.  Talk about becoming a lazy ham.  I just find them on the flex6700 and talk to them.  To put icing on the cake, since the tower tilts I added Al’s (NN4ZZ) http://www.nn4zz.com/HexLock.html  The only thing that is going to make heaven better is to have a zero noise level.  Did I mention that all Flex owners get a discount on the antenna.  

 

There are about 3 people making the antenna here in the states.  All are good and make a great antenna for the Flex radios.  It is also a very buildable antenna to home brew. 

 

Roger

NA4RR

Peter K1PGV

Another OCF user/lover here, about 40' up.  I'm using the Buckmaster one... perf just as Ken describes: works well except on 15 meters.

Peter
K1PGV

Kevin WB4AIO

Low SWR across the spectrum and flat receive frequency response across the spectrum are not the same thing. It is the latter that would be most desirable for utrawideband spectrum display.

The B&W version of these resistor-antennas is approximately 13 dB down from a dipole on 75 meters.

I have not made tests, but it wouldn't surprise me if a simple fan dipole had flatter receive response than one of these resistor-type antennas.

The resistor-types will have spots in the spectrum where they have high loss despite a perfect match. A plain dipole or fan dipole will have spots in the spectrum where the SWR goes very high -- but may receive well on those frequencies just the same, despite the loss due to the mismatch.

Steve N4LQ

This site has more info on these broadband antennas.
http://hflink.com/antenna/

Steve N4LQ

Steve N4LQ

Ebay is loaded with these things http://www.ebay.com/bhp/folded-dipole

Tom Warren

   I built the six-band center-loaded off-center-fed dipole by Serge Stroobandt, ON4AA. It's certainly not a StepIR but works very well and frees-up the tower for VHF/UHF yagis.
                                      http://hamwaves.com/cl-ocfd/en/  
Tom - W4TMW

kr4k

Cebik explains the theory that causes the low end knee effect you describe. 90 ft. versions of these terminated antennas are really for 4.5 MHz up. The BBA-100C 27m version ~ -8 dB, BBA-100Cs 20m ver ~ -15 dB, but the BBA-100Ce 57m ver < -1 dB from a dipole on 80m.

In any case, can highly recommend a 3-wire version over the 2-wire.

Barry N1EU

Sure looks like $335 worth of antenna to me (duh).

Barry N1EU

Steve N4LQ

Here's how you justify this. 

Either pay $335 for that antenna or pay $700 for an MFJ-998 auto tuner. 
So you buy the antenna instead and pocket the $365 or put it toward an amplifier 
to make up for the lost db
. 
The 16:1 balun is $35 from Buxcomm and those resistors total about $35 for 200 watts of dissipation. Add the wire cost and some insulators and you may hit $125 for parts. 

Al_NN4ZZ

Roger's hexagonal beam is also a good choice as the second antenna for diversity reception on the 6700.  I use several antennas for 80-6 meters connected to ANT 1 on the radio that are selected by an antenna switch.  I have the hexbeam connected to ANT2.   Works well for monitoring other bands in the second panadapter as well as diversity.  

Roger's antenna is well made and works great.   Check it out here:

http://www.k4hex.com/home.asp

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com


******** hexagonal beam right outside the shack *********

kr4k

Rotatable? Recommend Tennadyne T14.10-30HD and two BBA-1kDe. Or you could get the 19-element 1005-CA from arraysolutions.com, which weighs at 2100 lb., rated to 25 kW:
http://www.usantennaproducts.com/pdf/lp1001_1002_1005data_sheet.pdf

73/gus

kr4k

For a 53 m (175 ft.) 3-wire built using 3mm (0.125 in) 304, 7x19 stranded stainless wire, high power arraysolutions.com 16:1 BALUN, and heat-sinked Ohmite TA800 resistor, stainless hardware, insulators, etc, your cost will be about $600-750. Should be continuous duty, 1.5 kW.

That would be an ideal project to have connected to the 6700.

73/gus

KY6LA_Howard

Just to throw gasoline on the fire. Most of the time my 6700 is connected to a SteppIR MonstIR @85' Even when tuned to say 20M I find that I still hear a lot of signals on every other band I have an Alpha Delta 160m-10M dipole and a Pixel Loop. BUT I still hear more signals on the SteppIr on all bands at the same time than any of the other antennas which makes me wonder why people seem to be so concerned about needing broadband antennas. Likely the better performance of the tuned antenna is due to its height. 85' vs 30'.