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Author Topic: Give me the skinny on screwdrivers  (Read 920 times)
N2SUB
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Posts: 19




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« on: February 20, 2005, 06:07:35 PM »

Greetings all,

I have recently setup a station in my "antenna-restricted" community.  My neighbor is on the HOA - joy - so I must be very careful.  What I have done is to set an outpost tripod in the center of my backyard, out of view of the street - it is a "TEMPORARY STRUCTURE" that cannot be seen from the street!  They can't touch me  Smiley   With an outbacker Perth, the setup works great.  BUT....I'm getting tired of running in and out when I want to change bands.  I have heard of screwdriver antennas, but I do not know the first thing about them.  so....what is available.  What kind of performance will I get (vs the outbacker).  Will I be able to cover 80-10?  Are they more visible than the outbacker?  What else do I need to operate with an FT-1000MP?  Your help is most appreciated!
Jim,
N2SUB  
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WB2WIK
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Posts: 20595




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« Reply #1 on: February 21, 2005, 11:43:40 AM »

There are many screwdriver antennas on the market, and many to choose from.  Obviously, none defy the laws of physics and thus the "big" screwdrivers with larger coils and longer radiating surfaces (taller antennas) work better than the smaller ones do.

Drawbacks, though: Although you won't have to run in and out so much, you will need to run a second control line from the shack to the antenna to provide power and direction control for the motorized antenna.  So, that's another wire to deal with.  Also, screwdriver antennas have motors in them which generate audible noise and often that noise is amplified by whatever the antenna is attached to.  You might dampen the noise experimentally, but it's very possible the noise generated by the rotation of the mechanism will be heard by neighbors, giving them one more thing to complain about.

The higher-performance screwdriver antennas also are fairly tall (7 feet plus) and rather "heavy" compared with the Outbacker whip, which is quite light weight.  The Outpost tripod is pretty sturdy, but it may not handle a tall screwdriver antenna in a strong wind, so you might find your whole system laying on its side, on the ground, and possibly broken, one day if you're not careful to use it only in calmer weather.

I'd probably just continue running outside to change bands, myself!  But the screwdriver definitely has possibilities and may outperform your Outbacker whip on some frequencies if you don't mind the cost, noise, weight and extra cabling.  The "good ones" really are 7'+ tall and can cost over $300 -- but they're worth it, when you look at them.  Nobody's getting rich from screwdriver antenna sales.

WB2WIK/6

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K6TTE
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Posts: 70




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« Reply #2 on: February 24, 2005, 01:34:21 PM »

I'm in the same boat.  After doing some research, I recently ordered an antenna from Hi-Q.  You might want to check them out.  They seem to have some advantages over the other motorized screwdrivers.

www.hiqantennas.com

--Dale
K6TTE
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WB2IVU
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Posts: 19




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« Reply #3 on: February 25, 2005, 08:19:59 AM »

Why didn't you use your gutters and and an antenna tuner? That's a very simple stealth antenna that works very well.
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KF6RDN
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Posts: 39




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« Reply #4 on: March 04, 2005, 10:21:55 AM »

I've had very good luck with a mag loop. mfj-1788, but it's limited 15-40 meters, but if you want to do homebrew..  I was very skeptical that such a small antenna would work... but getting very good reports.

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N0EW
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Posts: 50


WWW

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« Reply #5 on: March 04, 2005, 09:30:12 PM »

Look over http://www.thescrewdriver.com/
Very solid construction! I really like mine.

The various models are all the same except for the length of the metal tube in which the coil runs up / down.

About $400, and has everything you need except the coax and whip. Of course, running it to your back yard you will need additional control wire too.

Lee ke4vsk is a good guy, just tell him what you're up to and I'm certain he'll try to help you out.

As to answering questions you did NOT ask:

What about putting up a flag pole / stealth antenna?

There is a tuny black wire called "Silky Wire" which I believe I bought from www.thewireman.com (or less likely www.cablexperts.com). Extremely difficult to see and very strong stuff! 1,000 feet of it weighs less than one pound.

Good luck!
-Erik n0ew
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N0EW
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Posts: 50


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« Reply #6 on: March 04, 2005, 09:41:34 PM »

Ooops! Speaking of not answering questions you asked!

Regarding http://www.thescrewdriver.com/

10- through 80-meters full power rated at 1,500 watts.
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N0MTC
Member

Posts: 12




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« Reply #7 on: March 15, 2005, 05:48:19 PM »

I understand where you are coming from. I have lived in a n apartment for about 3 years now and looked at all kinds of antennas for stealth. For me, I picked up the Tarheel model 100A screwdriver antenna (10-80m). It works great as I mounted it on a tripod and used a coaxial braid soldered to a clamp to attach to the all welded metal stairs to the second floor. PSK was my main mode and have made contacts coast to coast. Voice worked well but I limited myself as I possibly could be heard on near by stereo's(mine sure did from time to time). Having it on a  tripod help keep the motor noise low. Never had any complaints. Now live in a house with CC&R and looking to set it up again to be back on the air. Just remember, when asked, just say it is a bug repeller. (keep the citronella candles near by).
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N6AJR
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Posts: 9906




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« Reply #8 on: March 16, 2005, 05:46:58 PM »

look at a real DK 3 by Mr. Don Johnson, the only one you are to mount to ground, all the rest have to be isolated.

http://www.hamradiotoys.com/dk3.htm

this guy sells them for don,

you add a 12 volt supply for power and a double throw, double pole, switch for the up and down. you just tune it for maximum rf on a field strength meter. the antenna is designeed to be mounted on a ground ( metal picknick table??) and has a matching network to give you 50 ohms all the time, just run the antenna up and down to max transmited signal on the field strength meter

a Field Strength Meter is basically and antenna 6 inches tall hooked to a diode, and a resistor across a meter movement. the more rf, the more current detected, the higher the reading. when the antenna is resonant it transfers the most signal to the eather so max signal means it's tuned

it is not a 5 element monobander, but it is better than nuttin. you put a 5 to 8 foot whip ( for fixed I would use the full 8 foot or so tall cb whip.) and tune. so antenna all the way down, you get 10 meters ( just the whip is working, the coils are bypassed.) On the other end you have almost all the coils in use and the whip too so you can actually work 80 meters, actually pretty well.

if you use the shortend whip, you can work from 6 meters to 40 meters.

hope this help. Don Johnson is a real guy, his call is on the call search, and he also has a book call mobileering or something like that which is like 50 years of mobile experiance.

also if you can't put up an antenna in the yard, park that extra car, near the house and run your coax to the antenna mounted on the car.

also can you put up a flag pole ?? (force sells a 40 -10 meter flag pole)

any ideas yet..
I was in a restricted apartment, so I put up a fan dipole flat on the back of the roof, it worked and no one ever knew it was there, it 's been 30 years or so, but it may still be there, for a pieece of coax and some wire, I didn't even bother to take it down , I just whacked the coax off and tossed it on the roof.

http://www.hamuniverse.com/multidipole.html


good luck


73 Tom N6AJR
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W1YR
Member

Posts: 2




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« Reply #9 on: May 07, 2005, 08:18:13 AM »

It's been an education.

I have mentally purchased every screwdriver in production.  We are moving to development where the antenna can't be seen from the street so I have decided on a screwdriver or a tuneable dipole either of which can be put up and taken down in under 10 minutes.

I have not made my purchase yet BUT there is one site you have to go to which was mentioned in a previous post.  www.hiqantennas.com.  IMHO the manufacturers have an obligation to show technical specs.  There is too much rah rah on most sites.  "Best built.  Easy to install.  Still functioning after a direct hit by a 73 wheeler."  How about showing us, THE CONSUMER, how the antenna radiates and it's efficiency.

Enjoy whatever you purchase

73
W1YR
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N0GBR
Member

Posts: 24




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« Reply #10 on: April 10, 2007, 08:42:03 AM »

Take a look at the Sigma 5 from Force 12.  I use it in my attic with good results.  However, only 10,12,15,20m bands.  Controlled from the shack.  Can hang plants from their "garden" variey Sigma 5!  73  John
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