Testing Portable Antenna

[a71an]

http://www.dxqsl.net/attachment.php?attachmentid=16&stc=1&d=1224006886

I went this after noon along with A71BR, VU3MUV and myself to test a portable antenna on 40M, more details and photos will be posted by A71BR in this thread soon.

[A71CV]

Good morning my friend Rashed
It seem that you, A71BR, and VU3MUV had great time yesterday.
I am looking forward to know the result of the test and waiting for A71BR post

Good job guys :cool:

73

[a71br]

GOOD MORNING EVERY ONE

It was nice attempt yesterday, everything was set up but we face tuning trouble, A71AN say it's not grounded will........
We will try again next week.

73s

http://www.qsl.net/a71a/11.JPG

[N2RJ]

Maybe the antenna is too low to the ground?

When I had my beam on the ground, less than 1 meter over the ground, I could not get SWR better than 1.7. Now it is up in the air, the SWR is 1.1-1.2.

Perhaps the ground is detuning the antenna and causing some problems.

[a71br]

Anything can be happened and effect the swr but Rashid say that we need to
ground the antenna so we will try this week.

[AH6OY]

That is a pretty fancy antenna. Looks neat.

I've found by the books to get an accurate SWR reading the coax is best to be an electrical 1/4 wave length of the operating frequency. You figure the wave length for freq then multiply by the velocity factor of the coax which is around .66 for some coax like rg213. So your 1/4 wave coax ends up a little more than half the wave the 1/4 wave length. Verticals ground mounted with radials make good radiators with a low take off angle so your signal will take less hops getting around the world. If the sand is actual sand that is high silica bearing then it acts as an insulator not RF eater like dirt bearing grounds. Radial would do good on real sand resonating the freq and having less loss. Some times having losses in radials systems is good since it leaves less reflected power. Horizontal dipoles for best results of lower take off angles normally need to be mounted up high to keep the signal from reflecting at a high take off angles into the air.

I had one of these arrive a couple days ago. I got the 43 foot MK-8 version. Now only if I would bring it home from work where I had it delivered.http://www.mgs4u.com/fiberglass-push-up-mast.htm
It looks real sturdy. My plan is to use it near the beach and the house. It can mount a wire dipole or vertical. The verticals can either be wire hanging from the fiberglass mast with radials on guy wires or an aluminum store bought vertical clamped to the top of the mast set up to only go as high as the 1 inch section or maybe smaller ones. I've always had good results with a ground mounted Butternut HF9V vertical because I ground the antenna into a salt water pool and use a lot of radials with some 1/4 wave and others longer up to 50 foot.

Another option you could try is phasing vertical antennas to get gain and directivity. That is what I am looking into doing this second time around playing with my radios. I've been off the air for a while :D

Me personally with the heats of the gulf region? I'd have to use my ATAS-100 or one of my band specific whips mounted on the jeep for day time. Or like you are at night outside in the cooler air experimenting :cool:

It would be nice if the bands would improve.

[a71br]

We did all things perfect flowing the instruction we did transmit with good low swr in my house no tuner, But i forget to mark the tune spot, thinking that it will be easy tuned out side.
I need time to do that in open field . its very sensitive antenna if you fix the swr on one cable say 10 meters length used same cable and same ground cable.

73s to all

[AH6OY]

I use an antenna analyzer called the Autek RF1 RF Analyst. The first one I bought in 1995 quit working in less than a week and they billed me for repair and shipping like a lot of other people that had the same problem. I hope they don't have that manufacturing problem again. Real small and very acurate device. I make sure I always have an extra 9 volt battery in case the RF1 gets low in power.

What I did getting my jeep ready for a chance to sit around outside with the radio is stop at a car stereo installation shop and bought some heavy duty wire. I think its 4 gauge maybe. There are some amazing thicknesses of power and speaker cable wires at stereo stores for guys that run mega watt amplifiers in their cars over here. The lowest loose of voltage is with the thicker wires so you can make longer runs outside the car. Braided is much better than single wire or stranded wire. The stereo shop wire normally is a grey tint and red tint wire so easy to figure which wire is positive and ground with a flashlight if things get disconnected. Other accessories like battery clamps designed for adding big amperage drawing devices to the battery with fuses, distribution blocks to split up power and those big fat cables that don't loose voltage too easy. I think with car stereo shops that install the big fat amplifiers are perfect for getting a good hook up for power to a mobile radio. These companies in the car stereo amplifier business have even gone into making gold plated battery clamps hehehe :D

All of you are doing way better than me. It has been months since I stopped at night to only work on the radio. I use the Google Earth program once in a while to zoom in on areas trying to figure out where would be a good place to set up but haven't made it out the door lately to check some places out. I did zoom in on the picnic site Umm Bad trying the same trick of trying to make it easy finding a place to set up. The maps on the program do seem to be 2005 oriented.

Great job gentlemen. Wishing you the best of luck setting up for the new solar cycle.

[vu3muv]

Hi all,
As it seems we forgot to mention the make and model of the antenna shown in the pic.
This antenna is called Tak-tenna from steve, link to his webstie is http://www.tak-tenna.com/ . he has good support system and answered immediately on all our email questions.
we were amazed with the look and feedback mentioned in the website. And so we bought 2 antennas ( one for 20 and one for 40 Mt band) . I used MFJ 269 antenna analyzer to tune it in A71Br parking lot where I was able get almost 1.2-3:1 SWR on 40. The antenna was mounted on normal camera tripod at 1.5 mt height. This antenna is like lets say single element dipole antenna fed near center(note near, not the center) but elements are coiled on vertical plane. The feed back posts in website shows that many users have tried this antenna near ground (less than 2 mts from ground) and got gr8 results. After getting good match , i connected it IC756ProIII on port 2. Port one was connected to 40 mt Zepp antenna nearby. We attempted to get best possible match in the center of the band ( 7.050 Mhz) without using any tuner. Zepp antenna performed like any wire dipole antenna. Rx Signal report were 59 to 59+ , Tak-tenna had 55 to 57 report on the same signal when we switched between antennas. However tak-tenna had lower noise table compared to zepp which had higher gain and higher noise table too, so over all , they were same to me since tak-tenna was bit quieter. Test equipment were
1. Good pair of ears and
2. IC 756ProIII meter reading.

Like A71BR mentioned , when the antenna was dismanteled( forgetting to mark the matched spot with marker was our biggest blunder) and transported to picnic area few miles away , we were unable to find good match on the beach after almost 2 hours of trial with analyzer and returned disappointed. I suspected the feed cable. However we are waiting for our next visit to same spot to try it again. Will post the findings after that.

Meanwhile we got new mobile HF antennas from Buxcomm based on A71AN's feedback and have been testing/tuning for last few days. Each antenna took any were from 10 minutes to 20 minutes of fiddling to get best match/lowest SWR. Once tuned , the antenna retained the setting. Will post back photos and field test reports soon.

Next field test/picnic will include the following setup.
Radio: Kenwood IC 480 Sat , IC 706
Antenna/s : Tak-tenna ( 40 and 20) , Buxcom mobile whip for 10, 20 , 30 , 40 mt bands and one Outbacker antenna.
Digital mode interface: Signalink SL1+
operator; A71AN , A71BR , VU3MUV and any one else who might be around that day.


Disclaimer: We here in DXQSL neither support or endorse any manufacturer or vendor or represent any brand of amateur radio equipments. We buy what we want and can afford, test them and use any ham related Items that we had bought. We have no specialized lab or test equipment other than MFJ 269 analyzer and lots of odd bits like most Hams and so we do not claim to be experts on the same. All our feed back and reports are same as most Hams would find/discover under normal test circumstances/conditions without any specialized conditions or equipments.We may have missed or erred in our test and if so, I apologize. Our motto is get best bang for our money and share our experience with every one. we invite feedback and experiences from all Hams.


best 73s
Murali
A7/VU3MUV
along with A71BR and A71AN

[vu3muv]

Maybe the antenna is too low to the ground?

When I had my beam on the ground, less than 1 meter over the ground, I could not get SWR better than 1.7. Now it is up in the air, the SWR is 1.1-1.2.

Perhaps the ground is detuning the antenna and causing some problems.
Could be , but same setup in different location gave be almost 1.2:1 SWR when tested with MFJ-269 , I suspected the feeder coax cable from rig to antenna , adding to that was the fact that the rig did not have any ground too. Next trial i will eliminate these issues and test.

Murali
VU3MUv

[a71an]

As I have previously stated this antenna is nowhere near an antenna being portable, it is missy and with very critical tuning, there was no problem with coax cables neither the grounding of the transmitter by any means affected this antenna to synchronize with band.
Testing other portable antennas for the last one week and modifying some of them to server other bands which they are not designed for , like the 30M and given a great result, makes me 100% sure that when I am operating portable I need an antenna which work for me without given hard time.