Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: MFJ Screwdriver Antenna MFJ-1668, MFJ-1664  (Read 2443 times)
CHARLOTTE001
Member

Posts: 18




Ignore
« on: November 10, 2006, 03:09:14 PM »

Hi has anyone got experience of the above antenna? I'm assuming they're the same unit just with different whips.

I'm considering purchasing one as my DHP ATX is a junk pile also the fly lead is annoying

Charlotte M3OYE
Logged
AD5X
Member

Posts: 1428




Ignore
« Reply #1 on: November 10, 2006, 03:46:12 PM »

The MFJ-1664 has a 2-foot long coil.  The MFJ-1668 has a 3-foot long coil.  I have a review of the MFJ-1664 on my website at www.ad5x.com.

Phil - AD5X
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #2 on: November 10, 2006, 05:54:29 PM »

There is more to mobile antenna efficiency than just the length, diameter, mounting scheme, matching scheme, or the manufacturer. In fact, it is ALL of these things.

The MFJ is made by Tarheel, and sold under the MFJ name. It is not the most efficient, nor is it the worst. On average, you get what you pay for. However, there is much more to it. I'll give you a good example.

A simple spirally wound antenna like the Hamstick, mounted correctly in the middle of the roof of a van or SUV, will easily out preform even a HiQ incorrectly mounted to a rear bumper of said vehicle. Putting this into words, coupling losses, ground losses, matching losses, and a few other considerations mean a lot more than the antenna itself.

That said, the usual rule of thumb is, the better the quality of the antenna, the better the installation must be to take full advantage of the reduced losses therein. In other words, the better the antenna, the better the installation must be if a benefit is to be gained.

If any "rule of thumb" is to be considered, it is simply this; do the best mounting installation you can, the best bonding installation you can, using the best mobile antenna you're willing to buy, and the results will be worth the effort extended. Anything less, it just that; less.

Alan, KØBG
www.k0bg.com
Logged

N5EAT
Member

Posts: 175




Ignore
« Reply #3 on: November 11, 2006, 10:21:48 AM »

I own one of these, and mine works really well.  However, when you get the unit home, be sure to tighten all the nuts on the antenna before you use it.

Other than a "loose nut" on mine - it has performed perfectly for around 8 months.  The quality of the individual parts of this antenna is quite good.
Logged
W9PMZ
Member

Posts: 573


WWW

Ignore
« Reply #4 on: November 15, 2006, 12:37:21 PM »

I have the 1668.  It's nice and work pretty good.  You'll need to make a matching device for 40M and 80M.

Only drawback is that they do not work in the rain due to the lack of a cover over the coil.

73,

Carl - W9PMZ
Logged
WX9DX
Member

Posts: 64




Ignore
« Reply #5 on: October 08, 2007, 07:43:48 PM »

Well, one of my best friends just bought one of these antennas and it works OK! The coil design was a little crummy as they use bare wire rather than enameled or coated wire of some kind. It also came with the top nut loose and we almost lost the antenna top. Lucky even to tighten it backup since you can't get to the other side of the screw/ nut on top. Then here is my question; ok what are you supposed to do on the days it rains? Stay in the garage? It seems to me that any company like Tarheel or MFJxxx would make a cover for the top of this to cover the coil from the weather? HUH?

Ok anyone found a supplier for a cool cover for this or is everyone just replacing coils every year? Or are you all using PCV pipe covers for this unit??

Please if you have any constructive answers to my questions please e-mail me so I can help my friend out before winter hits us and this thing turns into junk!

Thanks in advance.
wx9dx at mwii.net

Thanks!
Jimmy:)
Logged
AD7VH
Member

Posts: 12




Ignore
« Reply #6 on: May 21, 2009, 08:49:08 PM »

I have found that the MFJ-1668 is a great antenna with a couple mods. First, get rid of the telescoping whip, use a 102", and add a caphat. I have not found a HF mobile antenna that can compare to this setup. True, it is up in the air close to 14', and I have to tie it all down to my truck, but damn does it get out. The one thing that sucks after these mods, is the fact that you lose 10m & 12m, but for me this is worth it. Before I forget, I have also made another mod to add 160m. All I did for this mod was to add a coil to base of the antenna, that runs horizontal along the bumper on my truck. I actually worked Austria from Michigan using this setup on 160m SSB. Oh by the way, I am only using 100w.

I am working on another mod so I can use an amp with this antenna. I am also trying to come up with a plan to add a cover to keep out the rain.

I will say it can be a pain when it rains. I have to clean the antenna about every 2 months when it rains here. This is not too much of a problem, as I live in the high desert of east central Nevada and we only get about 10" of precipitation a year.

I have never had a problem working anybody I can hear using this antenna. This includes many countries on 75m, and many, many on 40m. I get told a lot that there is no way that I am running barefoot. I know quite a bit of this is dependent on conditions. However, I am told by many that I have the strongest barefoot mobile signal on 75m.

I know that there are many variables when working HF. So I don't want to hear any crap from the normal people (this is an old thread, so I doubt it will happen). Since I knows these things, and can design an antenna better than most. I just want to say that there is not many antennas out there that can compare to the MFJ-1668, and none for the money. True, to get the most out of it you have to modify it, but it is very much worth it.

How many people can say that they have a full quarter wave mobile antenna on 15m? Not many, but I can. This is the best thing going for the person that wants to work HF mobile, but wants something better than a junk hamstick or a slightly better than a dummy load hustler resonator.

I am just getting ready for the barrage of bulls**t that is going to ensue. Since there are people out there that believe that only they know the right way to setup an HF mobile antenna. Well, after dealing with this design for over 2 years, I would like somebody to show another one that is as good or better. Even from my calculations (and modeling to back it up) a HiQ is only about 1.2dB better than my antenna. I am not going to spend that much money for an extra 1.2dB, when I can put the money that I save towards other things -- once I get the antenna modified to handle higher power, the money that I save will buy a 500w amp. This would then be another 7dB and would be worth the money.

I this thread is old, but when I hear people bash this antenna, I have to say something. People that talk trash about the MFJ-1668 don't know what they are talking about. The other fact that most people don't realize about this antenna, is that it shorts from the top to the bottom, which makes it a center-loaded antenna on the higher bands. Well, it becomes a center loaded antenna on even 75m when I do my mods. This makes the bottom section of the antenna in effect a 1.5" whip, which I know helps the Q out some, and not using so much of the coil for the low bands helps reduce losses. This antenna if setup for the lowbands is a win-win.

How many people can say that they have almost 40 countries on 75m/80m from the mobile using 100w. Yes, I am an experienced DXer, and I have quite a bit of time mobile, and conditions were pretty damn good this winter, but the antenna deserves it's props regardless. I have done a couple comparison test: my mobile is not even 10dB behind my base with a vertical with an extensive radial field. On 40m it is very close to my hustler 4btv with a few radials. On 20m my mobile is actually stronger than the hustler 4btv ground mounted.

If anybody has any questions as to what I did, or anything else, feel free to email me.
AD7VH at arrl dot net

73, John, AD7VH, east central Nevada      
Logged
WW5AA
Member

Posts: 2086




Ignore
« Reply #7 on: May 22, 2009, 07:46:04 AM »

Just do what Don Johnson did on the DK-3, cover the coil with a motor cycle front shock cover.

73 de Lindy
Logged
WW5AA
Member

Posts: 2086




Ignore
« Reply #8 on: May 22, 2009, 08:27:31 AM »

A little Tarheel II on my PT Cruiser, 160 meters with MFJ 12' whip, 80-6 with the 37 inch whip. I have 31 countries and WAS on 160, 71 countries and WAS on 75 meters all through LoTW. It’s just a matter of how much time you have to spend and how dedicated you are. It doesn't tell you a thing about how efficient the antenna is.

73
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!