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Tech833
Moderator
Username: Tech833
Post Number: 1769
Registered: 8-2002
| | Posted on Tuesday, November 10, 2009 - 1:53 am: | 
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Guys and gals, I ask this here in the Open Forum because I need help, and I value your opinions.
I am undertaking a project that may be the first of its kind, and something that will hopefully help people for many years to come.
The Forum Master, like me, has always wondered if those 'giant coil' mobile CB antennas are just hype, or if they really do have some advantage over other types of antennas one would use on a truck.
I was personally interested enough that I bought some antennas specifically for this test. Then, one antenna manufacturer heard what I was thinking about doing and sent me a couple of their 'giant coil' antennas to include. Then, Copper Forum Master sent me some antennas from the Copper Electronics warehouse to include. Then, I solicited 'giant coil' antennas from the rest of the well known makers, and all but 1 sent me one to play with. So now, I have several different 'giant coil' antennas, and several other 'normal' antennas to try and see if there is a performance difference. And, most important, if there is a difference, how much?
In the 'giant coil' corner, I have a Workman SP-3000, Whiskey Still, Whiskey Still Light, Wilson 5000 trucker, Monkey Made MM9, a Road King oil filled, and a borrowed Predator dual coil (Predator did not return my emails, so a friend loaned his).
In the 'normal antenna' corner, I have Copper's Night Sticks, K40 fiberglass, base loaded 'Half Breed', top loaded 'Half Breed', 5-foot Wilson fiberglass, 3-foot Firestik, 5-foot Van Ordt 'Pow-R-Stick', and of course a 102 inch 1/4 wave whip.
This will NOT be a 'shootout' format. I decided to do this a little more scientifically by using the antenna range to run polar patterns on them, measure current distribution and calculate Q, and then overall efficiency. I plan to use the 1/4 wave whip as the 'calibration' and normalize its performance to a 100% efficiency starting point. Yes, I know, 1/4 wave whips are not 100% efficient, I just need a calibration point. Beyond this, I really don't know for sure what would be helpful to you, as mobile antennas really aren't my typical area of study.
Here's where you come in.
I need to know of any other parameters or comparisons that are important to you. Like, comparing windload, comparing stiffness, comparing weight, etc. What do you need to know when choosing one mobile antenna over another? How important is bandwidth? Power handling? Stress on mounts? Bling factor? I want to know.
This project will take a great deal of time, as you may imagine. And, the results may not be a simple 'This is the antenna to buy!'. I don't want to pick a single antenna and assume it is best for everyone. I want to be able to create tests and discover and report data that will be useful to those of you who buy antennas based on more than just their cost.
Please keep your posts here based on what you feel is an important test or data to include in this piece.
Thank you,
Tech 833 |
Tech237
Moderator
Username: Tech237
Post Number: 1249
Registered: 4-2004
| | Posted on Tuesday, November 10, 2009 - 10:04 am: |
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As someone who does installs, I am interested in the mounting requirements - stress on the mount, body panel etc, restrictions on where it can cannot be mounted etc.
Although not a giant coil type antenna I'd also be interested in seeing how a Optek HVT-400B (which I run mobile) stacks up aganst them. Although I have not tried it, as it runs 80-2m I assume it will tune for 11m too.
Simon
Tech237
N7AUS
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I thought he said, "there was no rust for the wicked, and I own an MGB"
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Press_man
Member
Username: Press_man
Post Number: 78
Registered: 5-2008
| | Posted on Monday, November 16, 2009 - 8:25 pm: |
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Paul;
As an interested user I'd be interested in:
Gain
Stress on mount and where best mounted
Amount of hype
Static
Bandwidth
Weakness of construction
Tried a Monkey Made once, liked it, weak at the coil though and rough on mount point. 2cent worth.
Wally/Pressman/KC4ZWM
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Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4726
Registered: 7-2004
| | Posted on Tuesday, November 17, 2009 - 9:59 pm: |
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i've used 'big coil' antennas since the late 80's. the 1st that i settled on as 'good', overall performance-wise and windload/keep-it-on-the-truck-ability-wise, was marketed by h&y around that time, called a 'galaxy 25kw'. don't know ANY who-what-where about it, other then 1.1:1 swr was obtainable, and i could cover 26.700-27.00 with swr well under 2:1, which was more like 1.5:1. real-world, it 'did better' then all the 'cb' antennas i tried from wilson, solarcon a3000, van ordt, AS, 108" whip, skipshooter, etc etc. it spent MUCH of its life mounted on an 80's chevy blazer with fiberglas top. i welded 5" steel channel to the exterior rear mounted spare tire carrier, at 6" below the roofline, i welded a flat plate & bolted a ball mount to the top. it tuned to 1.1:1 readily with an swr meter, and a (quality) reflect reading watt meter showed i was right there with 1-2% reflect readings. later analyzer measurements showed differing readings-though i don't remember the exact #'s, i had to lower the
coil' on the antenna by shortening the steel channel & re-tuning the stinger AS WELL AS reshaping the spacing of the coil to get things closer to where the 'guru's' (remember, we're talking 20 years ago) said my analyzer #'s should be. did i notice any xmit/rcv differences? nope.
after it was stolen off my truck, i tried everything else i could get my hands on til i settled on predator 10k. vehicle changed to ford explorer the dodge durango. both required magnet mounting, and both used LARGE amplifiers that are generally considered NOT SUITABLE for magnet mounts. well THAT theory was disproved. magnet mounts & BIG amplifiers CAN WORK  . and i'm not talking 4 transistors here, driver input to main amp......well.....
anyway, that gives you an idea of MY requirements-
1.obviously, windload must be within reason, afterall this is NOT for shootouts, but actually while moving & it must stay attached to the vehicle without ripping the roof open/triple magnets off the roof
1a.must be relatively lightweight
2.swr/tuning must make amplifier use possible
3.needs to handle some power
4.needs to remain vertical at highway speeds
5.my predator has a 2:1 swr bandwidth of well over 2mhz, or more specifically, centered for 'best match' via reflect reading wattmeter around 27.500, i can show less then 4% reflect between 26.700 and 28.600, and better then 3:1 swr on 24.950 (however, analyzer readings again dispute efficiency the way antenna is presently tuned, if i lower 'best match' freq to 26.8 somewhere, then i can reverse above trend & match better on 12m. neither here nor there, 2:1 bandwidth over 2 megs is good.
6. bling is non-essential, the LESS the better. with a big coil EVERYBODY stares & the 'can you talk to mars' questions are now beyond annoying.
7. LENGTH. obviously, as close to 108" is best, my galaxy 25kw was around 80" overall, and my predator 10k is around 87".
so why not use a 108" whip??? real world, swr issues while moving when using power, TOO tall, capture area of thicker antenna gives appearance of better rcv & xmit.......
in 1979, i had the 1st (homemade) 2 transistor driving 8 transistor MOBILE amp around. everybody around here was using 4 (sweep) tube 2 piece mobiles doing about 400 watts on 12v DC. firesticks, francis whips & maycom's wouldn't handle the power. we used copper water pipe with a coil in it-to shorten it so i could drive with it-and lug connected it to the antenna and truck bed. don't remember the specifics, it was completely built & adjusted with a lafayette wattmeter. i think it worked better then ANY mobile antenna i've ever used. |
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