My Search for Portability
Matthew J Towe (KF4ZGZ)
on
July 3, 2002
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I am always looking for new frontiers: new modes, antennas, equipment.
Currently I have been bitten by the portable HF bug. Battery power, or lightweight switching
power supply, small rig and an antenna and away we go!
I have spent more time on the antenna end than anything.... for obvious reasons.
Here's what I have come up with:
for support, I purchased a MFJ telescoping mast. Light and compact. But how to support it? Guy wires, or cords would work, but then you
would be restricted to operating where you could tie them off. I built a folding PVC tripod. It is entirely self supporting and easy to
maneuver.
As for the antenna, it wasn't so easy. I have experimented with 'hamsticks',
dipoles, verticals and everything in between, Since my interest is mostly in
public service -disaster- communications and use on vacations, this ruled out verticals. Well, not really, I have had excellent results getting into state ARES
HF nets with a 'hamstick' on a camera tripod and a "capacitance " type ground system.
This is actually one of my favorites. Very small. compact and doesn't need a tuner as long as you
don't tune around too much. On the higher bands, you may even cover the whole band without a tuner ( I stole this idea from a
ham trying to sell an HF rig at Shelby, NC).
But when all possible signal is needed it leaves a bit to be desired. I finally
decided to build a dipole, but I wanted to multi-band it without a tuner. Yeah right! Either build a fan dipole or a trap. Both not fitting the bill for lightweight
portability. Feed it with ladder line? Nope, still need a tuner. Folded dipole
..ala TV ribbon? Well, that would work - for a single band. You would have to change the
capacitor, stub length and use a balun for multi-band use. Too much to carry.
So what already? A simple resonant dipole, fed with coax is all I need. The catch?
Build the highest band first. A 20 m dipole complete with insulators and tuned to
the band center. It will cover the entire band and the coax gives a 50-ohm load. No
tuner, no balun. Then instead of attaching support line to the other side of the
insulator, attach enough wire to resonate the next band of interest. Add an alligator
clip to jump the insulator and all you have to do to change bands....attach or remove
the alligator clip. Repeat as needed for all the bands. I decided to go from 17m -40m...
about 65 ft. This gives me an inverted vee self supported by the mast and the ends
are high enough for safety.
If I want to go to 80m...well, there's always a tuner.
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My Search for Portability
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by WB2WIK on July 3, 2002
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Nice job.
With a small tuner (MFJ-971 fits the bill at $99) I've found another cool trick: 40m roll-up dipole fed with 58 feet of TV-type (lightweight) 300 Ohm twin lead. The feedpoint Z at the "rig" end of the twin lead is just about 50 Ohms (1/2-wavelength of line repeats the doublet's impedance exactly without transformation), so I just plug the twin lead into a small 1:1 balun, and then use a short jumper of 50 Ohm coax to the rig for 40 meters. Ditto on 15 meters, where the dipole and the feedline are both 3/2 wavelengths long. On 20, 17, 12 and 10 meters, I eliminate the 1:1 balun and plug the twin lead into the "balanced" terminals of the tuner.
The entire antenna, including its feedline, can roll up into a 4" diameter ball and stuff into my pocket. The tuner attaches to the top of my Ten-Tec Scout with velcro (tuner weighs about one pound), and the station can be powered for several hours using a 7.5AH 12V gel cell, provided the Scout's turned down to 5W output. At the full 50W output level, the 7.5AH gel cell lasts about one hour of transmitting at a 50% duty cycle.
I made these comments only to remind folks that virtually _any_ feedline will work with a doublet, and mirror the doublet's feedpoint impedance, if the feedline (including provision for velocity factor) is trimmed to a multiple of 1/2-wavelength -- so we needn't be restricted to "coax," which can be bulky and has more loss than twin lead.
WB2WIK/6
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My Search for Portability
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by NB6Z on July 3, 2002
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I agree... It is hard to beat a 1/2 wave dipole for simplicity, predictability and low cost. They are efficient and, as pointed out, you can play tricks with the feedline to match your radio/tuner for different bands. If you can get a horizontal dipole up 1 wave high (or more) and clear from other objects, they make good DX antennas. I also would add that you can get even more gain, along with multi-band operation, when using longer center fed wires with twin-lead line, such as an Extended Double Zepp (EDZep).
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RE: My Search for Portability
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by N2EIO on July 4, 2002
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I keep searching for that perfect portable antenna, and I like your idea about the 40m dipole fed with 300 ohm twin lead. To take simplicity one step further, why not ditch the 1:1 balun and just feed the antenna thru the tuner ALL the time? The tuner can "match" the 50 ohms. Can you think of any downside to this? Thanks and 73, David (N2EIO)
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RE: My Search for Portability
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by VE3WMB on July 5, 2002
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Rather than a 40M dipole, try a 44ft doublette.
This antenna when fed with ladder line or Twin lead through a tuner will cover 10-40m. The advantage is that the lobes for all bands will be be in the same direction. Checkout the article by LB Cebik titled "Suppose I could only have one wire antenna" (http://www.cebik.com/aledz.html).
I use this setup with the DK9SQ Fiberglass mast (very similar to the MFJ mast).
Here are a few tricks .....
Use a small PVC T as the center insulator for the antenna. Lie the T flat and drill a hole through the side of each of the horizontal arms. This is where
you connect each leg of the doublette and the bottom, vertical part of the T is used along with a couple of cable ties to take the strain off of the feedpoint, by securing the twin lead or ladder line.
Next put the T upright into a vice and drill a
3/8" hole in the top of the T. This allows you to simply slide your center insulator over the top of the fiberglass mast. This beats tying or taping your antenna to the mast. And easily allows you to erect an inverted V with the center at about 30 ft. The T slides down the mast to a point where the diameter of the mast is such that it can take the strain.
Next if you want to guy your mast ... buy a standard guy ring designed for a tv mast (you can get these at home depot) and cut a 2 inch piece of black foam pipe insulation and stuff it through the middle of the guy ring. Now you can slip this over your fiberglass mast without fear of abrading the fiberglass.
Then precut 4 guys from lightweight nylon rope (brightly colored so you and others can avoid walking into them). At one end of each of these tie a loop and attach a small metal S-hook. The S-hooks attach to the guy ring. At the other end of the guys I make a small loop and stake the guys to the ground using a package of cheap screwdrivers as pegs (works like a charm).
The whole thing goes up in minutes and can withstand some pretty heavy winds.
I personally use a decent quality tv twin lead as a feedline and run it though a balun and then into my LDG autotuner.
One other trick. If you don't like using guys and are putting up your mast where the soil is well packed you can simple take a piece of ABS pipe somewhere between 1 to 2 feet long and sufficient size that the bottom of your fiberglass mast will fit inside. Attach it to a 3 foot length of aluminum angle stock using two or three stanless steel hose clamps of sufficient size. You want to leave enough of the angle stock sticking up above the top of the pipe so you can pound the support into the ground with a rock or hammer without damaging the top of the pipe. You probaby want somewhere between 8 inches to a foot (or more) of the angle stock protruding below the pipe to support the whole thing. Hint, take a hacksaw and saw the bottom ends of the angle stock to make it pointed ... it will still drive into the ground ok if it is flat but taking it to a point makes it a lot easier.
Michael VE3WMB
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My Search for Portability
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Anonymous post on July 7, 2002
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You are not alone trying to figure this one out. I always thought there were no ideal answers until I bought an AH-4 tuner. I can't put this tuner in my pocket and it really isn't all that small but it isn't all that large either. It only weighs about 4 pounds and requires no external power except from the xcvr. What makes this an ideal portable device isn't so much being automatic but its a remote tuner. I have used this tuner as far as 300 feet from the IC 718. Since the tuner can be remoted anything that can even remotely be considered an antenna will work and work well. A "loop" is a very good performer. There can be literally no feed line between tuner and antenna, they really become "one". I use the word "loop" loosely because it can look like any shape that is all or part horizontal / vertical. Other manufacturers make a similar product if you don't use Icom.
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My Search for Portability
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Anonymous post on July 7, 2002
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In case anyone wanted to know how I construct outdoor loops, I throw insulated wire on to trees, bushes, poles, parts of the house, whatever, and hook it to the AH-4 at a convenient spot. The best antenna I used only for a few hours was a vertical dipole made by hanging an AH-4 out a 5th story window. That antenna gave me over 12 new countries in less than 2 hours on 20 meters with about 10 watts out.
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RE: My Search for Portability
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by KD7LXO on July 8, 2002
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Good ideas on portablility in HF bands.
I've just been a'gettin' ready to go back on HF after a several year hiatus, and have new Gen ticket so I'm interested in 15-20-40-80, which my ol' Drake has.
My sole surviving antenna is a 40-80, trapped dipole which I've been threatening to "slingshot" up into the trees, but I sure like your idea of spring-clipping for 15-20, etc.
Would you mind sending me a little diagram of how I might connect the coax to the setup for this?
I'm a reasonably bright guy, but sometimes it takes me a while to dope out the most practical way to make something, and you probably have this deal down pat.
Thanks
John Merchant,JD
kd7lxo
jmer1627@aol.com
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My Search for Portability
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by W8PCK on July 10, 2002
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When I go portable I take my mobile dipole and mast set. Two identical mobile antennas mounted but to but with an easily obtained bracket (from R&L Electronics). One antenna is connected to the center of the coax and the other is attached to the shield. (I use PL-259 hardware to attach the coax.) When I want to change bands I just lower the mast (15 to 20 ft.) and attach a different set of mobile antennas. I keep the antennas in PVC pipes with end caps. Two pipes with antenna parts inside, 3 or 4 ea 5 ft. mast sections and I cover all the bands 6 through 80. All antennas are adjusted to resonance with an MFJ antenna meter and usually require little adjustment when used as a mobile whip. Works for me.
Ron w8pck
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My Search for Portability
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by KG8DP on July 11, 2002
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Equipment:
Icom 706MK2G with HS-706
New Wave Port-a-Pole 12 foot extension
New wave Big Foot mount for antenna. Secured by tire of auto.
Attach screwdriver antenna 80-6 m coverage
2 nuts to attach 12 volt power source
1 shade umbrella & Chair
all the fun you can stand. or at least I hope so. This is whats going to go with me to NA-052 in 2 weeks. Listen for us on the IOTA freq's and low bands. 73's Mark
www.qsl.net/na8kd
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My Search for Portability
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by KG8DP on July 11, 2002
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Equipment:
Icom 706MK2G with HS-706
New Wave Port-a-Pole 12 foot extension
New wave Big Foot mount for antenna. Secured by tire of auto.
Attach screwdriver antenna 80-6 m coverage
2 nuts to attach 12 volt power source
1 shade umbrella & Chair
all the fun you can stand. or at least I hope so. This is whats going to go with me to NA-052 in 2 weeks. Listen for us on the IOTA freq's and low bands. 73's Mark
www.qsl.net/na8kd
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RE: My Search for Portability
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by KR6EL on July 11, 2002
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use a bow & arrow(no tip!) will put it in a tree...forget a sling shot!!
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RE: My Search for Portability
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by KD7PKO on July 11, 2002
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IMHO, the best way to attach guys to any of the portable masts is to use a "simple" mast-head knot. Don't ask me to describe in words how to tie one, it would take forever and I would probably get confused with my own description!!! Basically, a mast-head knot is used for emergency support of sailboat masts, hence the name. When properly tied, the knot has three "loops" around the preimiter. Guys or "stays" are attached to the loops. As tension is pulled on the loops, the "center" of the knot gets tighter around the mast. This type of knot can be used with any shape, square, round, oval, etc. Get ahold of any local scout troop and they will probably be happy to tie one up for you. Once constructed, the knot can be loosened and used over and over. It also will allow repositioning when "freed up". For really tall portable masts, I use two, one at the top and one near the mid-point. So get out and help somebody earn their knot merrit badge and have 'em tie one on for ya!
73,
KD7PKO,Chris
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RE: My Search for Portability
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by KE4DRN on July 12, 2002
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Hi,
Here is a link for the masthead knot that
Chris suggested
http://www.northnet.org/ropeworks/archive/masthead.html
73 james
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My Search for Portability By NJ6F
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by NJ6F on July 13, 2002
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Greetings All,
Here is my solution to the portable situation.
Yeasu FT100D - 5.5 lbs with 100 watts! not just 5 assures me I will not waste my time trying to get someone.
MFJ 4125? new switching power supply 25 amps and only 2 lbs with no meters/ very small... I just love it.
Runs cool also. 115 and 220 switch.
I took it to Belgium with me portable and it worked great in the hotel room.
Antenna - I hate compromise...I want all the bands and the only decent antenna is a balanced...dipole for DX.
directivity, less noise on the sides, Lower angle for DX, and no ground plane wire hassles.
***** I use the Spider dipole antenna with balun and all bands...yes thats right it loads up on 6,10,12,15,20,30,40, and 75.
* Yes there are 2 coils for each band mounted on the end of each dipole and on a collar 6 inches in as well.
The coils are even adjustable with a ferrite ring on a numbered calibrated deal the length of the coil. Size of the coils for 20 for instance is 3/8 inch thick and maybe 2.5 feet long or so. No you dont need those Monster Hustler coils to get the job done. They are thin...up to 200 watts or so. I even use a vertical version of the dipole when mobile due to less wind resistance with the thin coils...less wind load.
The two extention aluminum poles are 4 foot each/ 2 of them in a fishing case with a balun where the reel goes. I carried it thru customs in Europe and US with not one question...they either thought it was ski poles or a fishing pole...I can even cut the 4 foot poles in half if I want them to go into a suitcase which I have not done yet.
This shortened dipole really works. I put it to test up on a 12 foot pole here in San Diego on 20 meters to Russia was S9 broadside and S2 with the antenna pointed away from the station...same for Japan. I feel there is not much sacrafice signal wise for these shortened dipoles.
ON the subject of getting the dipole out the hotel window I will be using a extentable MFJ non metal pole that I can ( swivel ) the dipole around once it is outside the window or use it in a field to just elevate the dipole vs using it as a swivel out a window with a string attached to the end to swivel it.
So there you go, a neat 100 watt effective all band setup. That you can bring in from your window after your done and pack it in your suitcase and fishing pole carrier in a few minutes.
Have fun
Regards,
Rich
NJ6F
El Cajon, CA
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My Search for Portability
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by W4WNT on July 13, 2002
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I tested out a Super Antenna MP-1 recently and found it very successful. I posted a short review on e-ham under product reviews. It even works with a camera tripod as the base.
Bill, W4WNT
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My Search for Portability
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by 9V1SM on July 13, 2002
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There is a group called HFPACK on yahoogroups of which I am a member. There are a lot of ideas going back and forth.
One antenna worth mentioning is the buddipole -an amazing little antenna. Dont get fooled by the looks. I have one and it has always amazed me! ;-)
try
www.qsl.net/w3ff
www.buddipole.com
73
Sasi
9V1SM / VU3SNM
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RE: My Search for Portability
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by AD5IU on July 14, 2002
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I second the vote for the home built Buddipole ( www.qsl.net/w3ff ). Bud has a new 'fancy' commercial version (www.buddipole.com) that I haven't tried but I can attest to his 'cheap & dirty' homebrew PVC version. The homebuilt version won't win any beauty contests but who cares? It is 'modular', breaking down into very small components for transporting. It is cheap to build (<$25 from scratch). and oh yea, it WORKS.
I use one of those 18' telescoping 'paintroller extension' poles you can find in Home Despot for a mast and it works far better than you might imagine.
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My Search for Portability
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by KF4ZGZ on July 17, 2002
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WOW! Thanks for all the comments guys. I was surprised and pleased when the article made the "front page". I realy didn't expect much from it so I didn't check the comments until recently...thanks again!
Now just a few remarks about the comments.
I wrote this to show what I had done and to show what is possible when you THINK! I may not have the science down pat, but I have been told by employers and friends in others hobbies that I have an ability with practicle application.
I wanted to carry as little as possible into the field...minus tuner and balun, thats about a pound. ( I use a MFJ 901b for portable.)
I take a flat piece of pvc, plexiglass, of whatever I
have thats rf proof and drill a 1/2" hole. I round the edges and put the mast through it to get it in the air as a center support.
If anyone is interested, I made quick diagram in MSPaint. Email me direct if you would like it or any other info. Look in the mail for notuner.zip
I also use the "hamstick dipole" with good results.
btw- I also use the hamsticks on a camera tripod with my version of the Alpha Delta capacitance ground. You'd be amazed.........!
When all else fails or I have a tall tree , I too use bow and arrow.
As for the discussion groups, I am a member of HFPack and The Live Wire Group. I highly suggest both for those who are into portable operation or antenna building.
Thanks again guys...73 de Matt, kf4zgz
and as always...
"The best antenna is the one you build yourself!"
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My Search for Portability
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by KF4ZGZ on July 17, 2002
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WOW! Thanks for all the comments guys. I was surprised and pleased when the article made the "front page". I realy didn't expect much from it so I didn't check the comments until recently...thanks again!
Now just a few remarks about the comments.
I wrote this to show what I had done and to show what is possible when you THINK! I may not have the science down pat, but I have been told by employers and friends in others hobbies that I have an ability with practicle application.
I wanted to carry as little as possible into the field...minus tuner and balun, thats about a pound. ( I use a MFJ 901b for portable.)
I take a flat piece of pvc, plexiglass, of whatever I
have thats rf proof and drill a 1/2" hole. I round the edges and put the mast through it to get it in the air as a center support.
If anyone is interested, I made quick diagram in MSPaint. Email me direct if you would like it or any other info. Look in the mail for notuner.zip
I also use the "hamstick dipole" with good results.
btw- I also use the hamsticks on a camera tripod with my version of the Alpha Delta capacitance ground. You'd be amazed.........!
When all else fails or I have a tall tree , I too use bow and arrow.
As for the discussion groups, I am a member of HFPack and The Live Wire Group. I highly suggest both for those who are into portable operation or antenna building.
Thanks again guys...73 de Matt, kf4zgz
and as always...
"The best antenna is the one you build yourself!"
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My Search for Portability
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by K6RXL on July 17, 2002
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For single-band operation, an end-fed, half-wave wire can't be beat! No bulky coax to carry and only one support is needed! The wire spools up on one neatly packed roll. And, the antenna is just as efficient as a center fed version! When used with the DK9SQ portable 33-ft fiberglass mast, you have a half-wave vertical which needs no radials (maybe just one as a counterpoise)! Or just hang in a tree and use vertical and throw away the mast! The possibilities are endless! The only downside is an antenna tuner is required due to the very high impedance with end-fed wires. I use a K1 with a built-in tuner so this, of course, is no problem.
If you are in the mood for some good homebrew, a VERY good multi-band (40 thru 10) portable vertical antenna project, cheap to build, and very efficient (condidering the design)...can be found in this month's QST (July 2002).
'73 and see ya all on the trails!!
Kevin
K6RXL
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My Search for Portability
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by N7QY on July 20, 2002
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How about one of Force 12's Sigma series vertical dipoles? I have the Sigma 5 good for 10-20, but they have one to cover thru 40, also.
See www.force12inc.com
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My Search for Portability
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by G3CWI on July 22, 2002
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Check out www.natworld.com/ars and www.qsl.net/g3cwi for portable tips!
73
Richard
G3CWI
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RE: My Search for Portability
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by K2GW on July 26, 2002
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>>you can simple take a piece of ABS pipe somewhere between 1 to 2 feet long and sufficient size that the bottom of your fiberglass mast will fit inside. Attach it to a 3 foot length of aluminum angle stock using two or three stanless steel hose clamps of sufficient size. You want to leave enough of the angle stock sticking up above the top of the pipe so you can pound the support into the ground with a rock or hammer without damaging the top of the pipe. You probaby want somewhere between 8 inches to a foot (or more) of the angle stock protruding below the pipe to support the whole thing.
Good Idea.
For a quick, no construction support for my DK9SQ mast, I've also used a five foot steel fence post (the kind use to support wire fences) and two velco cable straps from the Home Depot. The mast nestles into the curved side of the fence post quite nicely. It's a bit heavier and longer, but if you're car portable it's OK. BTW, A small block of two by four protects anything you're driving in with a hammer.
Another idea I've seen for use on paved surfaces (such as is often the case near shelters and EOC's) is to take a piece of PVC pipe larger than the mast, place it in a 5 gallon plastic bucket and fill the bucket with cement. Not something you would want to backpack with, but it works with the the relative light weight of the DK9 SQ mast.
73
Gary, K2GW
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