| Author |
Message |
    
mikefromms
| | Posted on Thursday, June 26, 2003 - 6:37 pm: | 
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Well, I have my new President Lincoln. Reminds me a lot of my old (10 years ago) Uniden 2510, which I loved. This radio has a built in swr meter and so I used it to check the swr on my astroplane. I'm puzzled...the astroplane is supposed to have good swr(acceptable for transmitt) from 26mhz to somewhere up in the 28 mhz band. Mine gives acceptable reading with full rf power turned to the right only from about 27.700 to 28.850. Here I can get 2:1 or less. The lowest readings are around 28.450 with a 1:2 reading on full power. I am very disappointed about this.
Maybe you can help me find my problem as we explore the variables.
1)Using 50ft. of Radio Shack RG-58-U coax with the smaller connectors pieced together from the factory.
2)Coax wrapped around the support pole coming down the pole for a 10'run.
3)Coax cut to wrong length.
4)Meter on radio defective after mods. (won't send it back if it is).
5)Common problem with type of antenna.
6)Coax size (diameter of conductor wire) affects bandwidth.
7)antenna too close to shingled roof (bottom ring ten inches).
What do you guys think? Any other variables? What would you correct first?
Mikefromms |
Keithinatlanta
| | Posted on Thursday, June 26, 2003 - 7:32 pm: |
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If you have the coax "wrapped around the pole", I would think that that is as bad as coiling up the wire because you had extra coax. Let it hang straight down until you send it into the house.
I would also suggest that you utilize a good external swr meter when checking as you can always unplug it when done.
Hey everybody, am I even close?
Keith in Atlanta |
mikefromms
| | Posted on Thursday, June 26, 2003 - 10:54 pm: |
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Thanks Keith. Right after I started this new topic it started raining hard. After I got off the computer I went back to check the dx conditions and swr. Surprise! Swr was flat right on channel 20 of 27 mhz band. With the antenna and coax wet the frequencies under 2:1 swr ranged from 26000 to 28500 (close in that range). Now I can live with that. Now, a new question is factored into the equation (which I feel very experienced folks will quickly remedy): why did the swr drop to flat and useable over a broadband area when it was raining? I'm sure someone has seen this condition before and has the answer.
Thanks for any help you can give. Oh, I talked to New Orleans, short skip this afternoon. First dx contact on Lincoln and AP.
Mikefromms |
Damyankee
| | Posted on Friday, June 27, 2003 - 12:47 am: |
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Mike.
I'm leaning toward a few possibilities here.
1st - Junk The RAD Shack Coax! Your connectors are likely crimped on, the core is solid & the shield is maybe 80%. Marginal for mobile, not suited for a base set-up. 2nd - Unwrap the coax like Keith suggested. 3rd - Make absolutely sure that you have a good ground (to the ground) from the antenna & pole. Think, rain, water, good conductor to ground...Bury that ground rod deep & water it if necessary. 73's - Ron 340 Ark |
mikefromms
| | Posted on Friday, June 27, 2003 - 7:12 am: |
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Thanks for the comments. The coax claims to be suitable for this application but I have my doubts too. The ground should be good, but I though the AP would operate on its own without an extra ground. I'll unwrap the coax first and see what effect that has. I can also wet the ground rod the next time the swr rises and see if anything changes. Next, wet the antenna and coax. I appreciate all feedback. I hope the coax isn't so thinly shielded that the rain helped to ground it and otherwise it's not making good ground through the shields as it is. We'll just have to see.
MikefromMs |
Tech833
| | Posted on Friday, June 27, 2003 - 10:43 am: |
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Mike,
There is a problem, that is obvious. Your SWR should not change at all when the antenna gets wet or dry.
First of all, make sure that you scuffed up the aluminum where the pieces meet and where the hardware touches it. Also, make sure that you did not wrap tape around anything except the coax connector. One thing that happens a lot is the coax getting pulled where it goes into the connector that screws in to the antenna. Make certain that all the hardware is tight! Use an Allen wrench to make sure the cap head screws on the top bracket are all tight and making good electrical contact.
Now, about that 'wrapped' coax. Unwrap it. Secure the coax to the mast using electrical tape or tie wraps (use the black ones). Be sure your coax is nowhere near the aluminum elements, especially at the ring. Run the coax all the way down to the roof before it leaves the mast.
Those Radio Shack RG 58 crimp connectors are notorious for not getting crimped around the braid properly. I would highly suggest replacing the connectors with the solder type.
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mikefromms
| | Posted on Friday, June 27, 2003 - 6:41 pm: |
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Thanks for the feedback. I'll start with the simple things and work from there.
Some of the things you mine tech833 bring some questions to mind. I noticed on the antenna where you screw the top radiating element into the piece where the coax connects there is a set screw. It appears that the top radiator screws down against it and the piece coming from the bottom screws in tight against it. Is this this correct or was I supposed to screw the set screw out and screw the elements in until they meet (if possible) and then screw the set screw back in?
To the best of my knowledge I thought I put the antenna together right. I'll start correcting things soon. I agree, the swr should not change when wet or dry. Thanks and all comments are welcomed.
Mikefromms |
mikefromms
| | Posted on Friday, June 27, 2003 - 6:44 pm: |
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Tech833, when you said make sure the tape is not wrapped around anything but the connector, were you saying it's a bad idea to tape the coax to the mast with electrical tape or did you just mean the antenna itself?
Thanks,
Mikefromms |
Tech833
| | Posted on Friday, June 27, 2003 - 9:14 pm: |
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Mike,
You should have backed those screws out when you threaded the elements in and then re-tightened them. That would seat the aluminum tubing tightly into the insulating nylon inserts and make the metal-to-metal contact better.
Taping the coax to the mast is fine. I was referring to taping the elements. I read somewhere that someone had wrapped tape around all the aluminum to 'protect it' then couldn't figure out why it didn't work. Answer: The tape lowers the velocity factor of the antenna tubing material and would detune it. |
mikefromms
| | Posted on Friday, June 27, 2003 - 11:24 pm: |
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Ok. Antenna is coming down. So the rain probably was causing a better connection in the elements? It's so strange, though, because I'm getting good swr on 28 mhz. I think I'll swap out coax when I readjust the antenna.
Now that I think about it, I don't remember the instructions mentioning backing out the set screws. They didn't even provide a tool for this one. So if I back out the big allen screws and screw the elements on down then tighten up the allen screws this should fix the problem? Sounds logical. It'll be fun working in the antenna on the roof tomorrow.
Mikefromms |
Tech833
| | Posted on Saturday, June 28, 2003 - 10:54 am: |
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The instructions are lacking, to be kind. One of my many, many projects for Copper was to write a new manual for this antenna complete with pictures. |
RCI 2990
| | Posted on Saturday, June 28, 2003 - 2:07 pm: |
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Mikefromms...
I bought a astroplane clone and have no SWR problems to speak of but what i did was cut the aluminum were the 2 radial sections join up in the middle with the bolts and nuts and made a trombone type of connection securing with hose clamps so that i can fine tune the antenna. It also beefs up the antenna as well since i used heavier aluminum in the 2 radials that go down to the hoop.. It will work fo you as well.. |
mikefromms
| | Posted on Saturday, June 28, 2003 - 9:55 pm: |
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Thanks for the suggestion. I worked on the antenna for several hours today. My labor was rewarded with acceptable swr 2:1 or less over the cb band up through about 28.880. Next project will be to replace the coax. I'm getting good reports on the set up. When folks hear I'm barely above the roof they sound surprised.
The Lincoln is so loud one guy told me to turn my power back because I was somewhat muffling. It cleared right up. Anyway, I feel very good about the set up and know that it will be an even better set up when I replace the Rad Shack baby coax.
Mikefromms |
RCI 2990
| | Posted on Sunday, June 29, 2003 - 12:44 pm: |
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I had mine barely 5' off the ground and i had a 1.2=1 swr all 40 plus the uppers and lowere as well. Darn good antenna i say! I tested it with my cobra 142GTL in line and made a few contacts as well.. |
mikefromms
| | Posted on Sunday, June 29, 2003 - 5:39 pm: |
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I think I will have to lengthen mine somehow to get the lower channels. Could have something to do with the small RAd Shack coax. How would mini-8x work compared to the 58U I'm runnin? Only need about 40 ft.
Mikefromms |
RCI 2990
| | Posted on Sunday, June 29, 2003 - 9:34 pm: |
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Lose the cheapo coax and get some RG 8 or the like LMR 400 is the best as well as RG 9913..
I modded mine and made it so i can move the 2 main radials (the ones that join the upper section to the hoop.) in and out to adjust my SWRs to were i want to be.. I had a 1.2-1 swr out of the box with a short piece of RG 8U coax going from the radio to the antenna. When i made the antenna adjustable i could get the swrs down to a 1.1-1 all 40 plus... :-) |
mikefromms
| | Posted on Sunday, June 29, 2003 - 10:54 pm: |
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Wow, I'd be afraid of screwing the whole thing up.
Glad it worked out for you.
Mikefromms |
Tech833
| | Posted on Monday, June 30, 2003 - 11:22 am: |
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Mike,
Replace that cable before you go changing anything else. You have talked about it enough, DO IT!! |
mikefromms
| | Posted on Monday, June 30, 2003 - 8:17 pm: |
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Time to act. How about that mini 8x coax for a 42 ft run? I'd like to stay with small diameter if possible.
Mikefromms |
RCI 2990
| | Posted on Tuesday, July 01, 2003 - 1:27 am: |
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What you need to do(and no you will not mess it up either) is measure the antennas radials and then write down the measurements. Then cut off the 4 flat ends about 2" from the flat ends, the ends that join together were the mast mount bolts to the radials, then get some larger diameter aluminum tubing ( i used a section of scrap moonraker tubing) and slid the now hollow ends into the larger aluminum tubing and slide them in and out until you get the exact measurements you had before.. rember to use 2 hose clamps on each element! Tighten up one side and leave the other side loose to act as a adjustment. Viola! you now have a tuneable astroplane!!!!!! |
Highlander
| | Posted on Tuesday, July 01, 2003 - 7:37 am: |
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Don't skimp on the coax. Mini-8 will work, but you will lose too much received signal in it for weak signal contacts - Don't use any radio shack coax, get Belden 9913 or Times LMR-400. It makes no sense to buy a high performance antenna and feed it with lousy feed line. I'm just wondering, too - what IS your SWR on 26.000? If it is under 2.5, I wouldn't mess with it. There isn't that much going on down that low anyway. There is a calling freq 26.285USB (similar to 27.555, but not as busy), and some SSB activity around this freq, but usually only when conditions are very good will you hear much down there. |
Tech808
| | Posted on Tuesday, July 01, 2003 - 9:44 am: |
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mikefromms,
On Coax use RG8 or 8U with 95% Shield or RG213 or 213U 95%.
Both will work well for you.
The LMR400 is good but much more expensive, and on a 42' run you should not notice any real difference in performance as Attenuation is measured in db/100 per feet.
And use AMPHENOL CONNECTORS! They are well worth the little extra on these.
http://www.copperelectronics.com/cgi-bin/product_display.cgi?categories=COAX
http://www.copperelectronics.com/cgi-bin/product_display.cgi?categories=CONNECTORS
I would also suggest getting 50' as you get a break on price at 50' and this will leave you enough to make a couple of GOOD Jumpers.
No matter what kind of Radio Equipment you use ALWAYS use GOOD COAX, and CONNECTOR's.
It will save you a lot of headaches/problems later.
Just my Thought's.
Lon
Tech808
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Kirk
| | Posted on Tuesday, July 01, 2003 - 9:05 pm: |
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I agree on the RG-213 choice (for velocity factor sake) on HF. 9913 might give you problems. 9913 is typically best in VHF. |
RCI 2990
| | Posted on Wednesday, July 02, 2003 - 12:42 am: |
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I run 9913 on 27 MHZ CB and have had nothing but good luck with it.... Best coax ive ever used.. |
Tech833
| | Posted on Wednesday, July 02, 2003 - 9:39 am: |
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Kirk,
What? How? |
Moderator558
| | Posted on Wednesday, July 02, 2003 - 10:24 am: |
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MIKE
I was looking at some RAT SH!T coax some guy was selling at a hamfest,, he had several packages new. I said well that cant be to bad for the price he was asking. While I was picking out my packages I noticed a odd shape on 1 piece of cable.
The coax seemed to have a "bubble" in it. I asked the guy "I THOUGHT THIS WAS ALL NEW"
He replied "OH THATS NOTHING,,,,WHEN IN THE MANUFACTURE PROCESS IF THE LENGTH ENDS BEFORE THE SPOOL IS COMPLETE THEY JUST BOND ANOTHER RUN OF COAX TO COMPLETE THE SPOOL,,,IT DOESNT HURT A THING"
I set down the packages I had in my hand and walked away,,,,DID NOT WANT TO TAKE THE CHANCE
thats my opinion on the matter.
The LMR is GREAT COAX but for 27 Mhz,,,,,, not worth the cost,,, IMHO,,,,,I use it on my radio for 432.1 Mhz,,,when that high on Freq it does matter!!!
just get that stuff from copper and use good connectors.
I have a question?
How do you have the antenna in the air? Mounted to a mast on a tri pod? Is the mast grounded? Is the mast a painted mast?
Tech833 I have a question because I do not know?
Can you coil the coax near the loop on that antenna to make a RF CHOKE? I have 8 wraps in a coil about 6 inches in diameter for my ANT99 and I no longer "bleed" the neighbors TV which is good 
heres where I got the info:
http://www.radiohc.org/Distributions/Dxers/coax-rf.html |
Twa77
| | Posted on Wednesday, July 02, 2003 - 10:29 am: |
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you get what you pay for |
mikefromms
| | Posted on Wednesday, July 02, 2003 - 1:22 pm: |
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Mod558, your coiling trick seems to have done the trick.
I have mine on a 10 ft pole from Rad shack (maybe it is defective, ha!). I have wondered if I am too close to the roof of the house. At least half of my bottom ring is less than two feet from the roof and there's this metal air circulator from the attic not 5 feet from the antenna. Could this affect the broadbandedness of the antenna? My antenna is now good for like 26.900mhz to 28.880mhz before the swr is too high for comfort. I won't tranmit on it once it reads a 3 swr on my swr meter.
mikefromms |
Tech833
| | Posted on Wednesday, July 02, 2003 - 11:37 pm: |
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TWA,
Coiling the cable really won't hurt anything. However, on some antennas like the Top One, it might.
Mike,
You never mentioned the large metal object near your antenna before. Can you get the antenna another foot or so higher? Can you angle it away from the roof a little? One more thing, change your coax! You've been talking about it for something like 2 weeks already. We are all waiting. |
mikefromms
| | Posted on Thursday, July 03, 2003 - 7:11 am: |
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When I change coax maybe my wife won't hear me coming over the computer speakers! I think I will go up another few feet. Anyway, it's a plan.
mikefromms |
Kirk
| | Posted on Thursday, July 03, 2003 - 4:34 pm: |
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Tech 833-
I was once informed that using 9913 in the HF section (and just to clarify I used a single feedline to feed 20 thru 80 meters of antennas with a remote antenna switch) that it would possibly create problems when treansmitting in the HF bands. Am I mistaken?
I think a good thing about 213 is it's flexible (although 9913 F is also) but 213 tends to be cheaper.
Anyway, my exprerience of trouble in this was a 50 ft piece of 9913 (used as mentioned above) gave me erratic SWR readings. Now this could have been a connector/connection issue...but I took down the 9913 and put up 213 and the problem went away and never surfaced again.
Another plus (for me personally) in using 213 was it was flexible. The 9913 I used was rigid [before 9913 F existed that i knew of]. We all know that the "air" dielectric in rigid 9913 could cause some issues down the road. |
Tech833
| | Posted on Friday, July 04, 2003 - 1:04 pm: |
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Kirk,
Not so. The velocity factor means almost nothing unless you are phasing cable fed antenna elements or doing some matching between elements or objects. It is the electrical vs. physical length. Look at it as a ratio if it helps.
9913 air causes what issues? If you do not pressurize it with dry air it might. However, anyone using air dielectric cable must know this. I have found superior results from air cable in my uses (high power/long term reliability). For CB it sure would be overkill.
My favorite cable for HF is still LMR-400. You can't beat the shielding and power capability for the size. I have to confess... I am planning a 10/11 meter antenna installation (for listening) at my new house. I will be using Cablewave 7/8 line with LMR-400 jumpers if that means anything. |
RCI 2990
| | Posted on Friday, July 04, 2003 - 2:13 pm: |
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I have had mine up for 3 years and NEVER had any issues ever.. Super low SWR across all 40 plus.. Also mine is the flexible coax.. Love it and will never buy anything else again.. Once again i will stand behind my convictions on this deal.. |
Tech833
| | Posted on Saturday, July 05, 2003 - 12:27 pm: |
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9913 certainly is good cable! 2990, you did good. |
RCI 2990
| | Posted on Saturday, July 05, 2003 - 7:18 pm: |
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I love it. I actually paid the same for 9913 as i would for the LMR 400. But im happy.. I used to bother the folkses TV every time i keyed up but i changed my coax and the interference almost went 100% bye bye!! Only gripe i have is it is hollow in the center so i had to seal the ends up at the antenna feedpoint with tape and coax seal but so far so good its been up there almsot 5 years now.. |
mikefromms
| | Posted on Sunday, July 06, 2003 - 6:02 pm: |
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Well, my swr continues to go down and I haven't done a thing in two weeks to the antenna system! Do you suppose the thing is getting broken in? It's really showing some broadband readings now. Wait till I get my new coax and go up a few feet! It's not too far away from being broadbanded enough to talk on the 10 meter repeaters.
mikefromms |
Kirk
| | Posted on Sunday, July 06, 2003 - 8:36 pm: |
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833-
"Air dialectric issues" would be the center conductor coming closer to the sheilding if too radical of a bend happened. Again I am taling the non-flex (i.e. nothing to firmly keep the center conductor evenly spaced between center conductor and sheild. And, water (moisture) actually getting inside. Had that happen. |
mikefromms
| | Posted on Sunday, July 06, 2003 - 11:08 pm: |
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Here are my latest swr reading on the Astroplane and I still haven't changed the coax or moved the antenna in two weeks:
26.000=3.0 swr
27.205=1.8
28.000=1.2
28.500=1.6
28.940=3.0
26.000 is as low as my radio goes. The 28.940 was my highest frequency before it would change to 3.1 swr. That's not really bad is it? I mean, that's pretty broadbanded. But I don't like transmitting at around 3 swr or more.
mikefromms |
Tech833
| | Posted on Monday, July 07, 2003 - 10:01 pm: |
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Something is still wrong. Your lowest reading should be at or near 27.200 MHz. Also, you should get nearly 1:1 at the center.
You know, my wife is one that talks about doing something for weeks and weeks before actually doing it. You and she would get along well. |
Tech808
| | Posted on Monday, July 07, 2003 - 11:16 pm: |
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Tech833,
Your the best!
Lon
Tech808 |
mikefromms
| | Posted on Tuesday, July 08, 2003 - 12:17 pm: |
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Well, I have ordered some coax. When the coax arrives I'll get a longer pole and do the work, if my sprained ankle will hold out on the slanted roof. Got a bad sprain last week--still swolen.
That was a good joke. Does your wife participate in the forum?
While I'm talking about doing something I'm also in the midst of planning and sometimes if you don't rush in you might discover something else you need to do once you start the job. Oh well, I guess this is one of those hobbies where "doing it again" is part of the fun.
mikefromms ()() ()--mine won't roll and laugh! |
Tech833
| | Posted on Tuesday, July 08, 2003 - 5:28 pm: |
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My wife does participate in the forum- indirectly. If not for her patience, I would not be here. |
Tech808
| | Posted on Tuesday, July 08, 2003 - 6:45 pm: |
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mikefromms,
Go to the left of this column and scroll down to the section Titled Documentation, then click on Formatting.
This area will show you how to add graphics/clipart to your post's.
You can make them Roll, Smile, Think, Wave and a lot of other neat things to draw more attention to your posts.
Hope this help's.
Lon
Tech808  |
mikefromms
| | Posted on Wednesday, July 09, 2003 - 6:17 pm: |
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Thanks Lon,
I really appreciate your helpfulness.
Looking forward to the review of the nbs-2010 Big Stick.
mikefromms |
Sixtiesmania
| | Posted on Saturday, July 19, 2003 - 8:43 am: |
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For god's sake!!! Please put us all out of our misery and bloody well change your coax and antenna height!!!!! This is worse than who shot "JR"!!!!!! Arhhhhhhhhhhhhhhhhhh!!!!!!! |
Kc0gxz
| | Posted on Saturday, July 19, 2003 - 12:59 pm: |
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Sixtiesmania
Thank you for saying what I was thinking.
Jeff, kc0gxz. |
mikefromms
| | Posted on Saturday, July 19, 2003 - 8:10 pm: |
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Ouch! The coax is in the mail. They had a back order. I'm going up 5 more feet and installing the latest Beldon (new improved) mini-8 coax. If I'm not happy with the swr I'll get another antenna. In fact, if I had it to do again, I wouldn't a copy of anything. I would buy a USA original product.
Who shot J.R? Was it Sue Ellen? I was like 19 years old with this was going on. LOL.
mikefromms |
Bullet
| | Posted on Sunday, July 20, 2003 - 9:30 am: |
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mikefromms,
you said its a 10 " rat shack mast,some of those are painted a off yellow color if this is one of the painted mast youll need to sand off the paint were the antenna bolts up to it.
i had a buddy in kentucky that was having swr problems like yours and he had a radio tech in that area come over and chant some mistic mumbo jumbo and do a rain dance, scratched his head and told him i cant figure this one out ill be back next week to try again.
he asked if id come over to take a look see. i walked the mast down sanded the paint off the ends scuffed the antenna mounting area,added a ground wire to the ubolts and run it to a ground rod that was thier but unused. and bam i was done. took like 15 minutes or so and vswr was right in place around 1.3vswr on ch 20 he was happy with that and so was i.
mini 8 is not much better than the 58 imo if i was going to replace coax id get 50' of lmr 400.
its only gonna cost about 30 bucks for 50 feet of the stuff and its the best youll ever need!! your gona pay about 20 bucks for that mini8 so whats 10 more dollars for the best youll ever need!!!
thiers 2 main things were your money matters the most.
1, a high quality antenna.
2, a high quality feedline.
do this and you can sound good on a yard sale radio. |
bruce
| | Posted on Sunday, July 20, 2003 - 10:03 am: |
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Sixties I realy never cared who shot JR .... i wasn't there ..... Heck my luck is so bad on being part of history that 34 years ago today man walked on the moon ......while i pulled guard duty at fort knox ...... by the way was it Sue ???? who cares LOL |
mikefromms
| | Posted on Sunday, July 20, 2003 - 6:12 pm: |
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Think it was Sue.
Bullet, this mini-8 will be a nice improvement over what I have plus it has hand soldered silver PL-259 ends. It's only 45 feet. Remember, we are talking about 10 and 11 meter bands. Not really critical until you are in the 100 ft or so range. I have Rat Shack coax with crummy ends. I want to stay with smaller coax because of the window bottom I'm coming in. You are right about the bigger coax being better, no doubt, but I don't run power.
Thanks very much for your advise on the Rat Shack Pole. You are right. I'll bet you that is more of a problem than the coax! I'll be sure to sand off that paint and do this thing right.
Do you think the AP clone is a high quality antenna? I won't be offended by the answer.
mikefromms |
Bullet
| | Posted on Monday, July 21, 2003 - 9:46 am: |
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mikefromms,
well to be honest ive not seen the clone (top one)
up close and personal.
ive seen the original astro plain,and was impressed with its performance at low height above the ground.
i had a buddy that ran one for close to 30 years at about 15ft high and it did real well for him. |
mikefromms
| | Posted on Monday, July 21, 2003 - 10:36 pm: |
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I don't want to keep one that long. Maybe six months so I can try something else!
mikefromms |
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