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: Screwdriver covering 6 to 160 bands ?  (Read 6341 times)
KF5BBB
Member

Posts: 9




Ignore
« on: March 22, 2011, 12:04:25 PM »

Is there a screwdriver antenna that covers all non 2 meter bands to mount on my motor home? 

Julius, KF5BBB
Logged
K0BG
Member

Posts: 9885


WWW

Ignore
« Reply #1 on: March 22, 2011, 01:16:14 PM »

Not per se. One has to remember that the overall length of a 6 meter, 1/4 wave vertical is only about 54 inches. As a result, any decently performing screwdriver will have an OL easily twice that length. It is possible to tune to a harmonic, but you still have a vertical. If you're serious about 6 meters, the best thing to use a horizontally polarized loop, especially if you catch an E layer opening.

There is another issue with a 160 meters. Most decent screwdrivers require some sort of matching. That's usually in the form of a shunt matching coil. Due to ground and coil losses, even a rather good screwdriver doesn't require matching. Therefore, some sort of switching arrangement has to be facilitated.

The Yaesu ATAS does cover 40 up, but even compared to a hamstick, it takes a back seat.
Logged

AJ3O
Member

Posts: 124




Ignore
« Reply #2 on: March 22, 2011, 01:24:28 PM »

The Tarheel Antennas - Little Tarheel HP = 7.0 - 54mhz & Little Tarheel II = 3.5 - 54mhz
http://www.tarheelantennas.com/

Hi-Q Antennas - They have several in their line up.
http://www.hiqantennas.com/

And there are others. Some independent Hams and more businesses.
Google Link: http://www.google.com/#sclient=psy&hl=en&q=screwdriver+antenna&aq=0&aqi=g5&aql=&oq=&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=a0e1d04ac32ef934

I will be looking for one myself in the next few months. Also, while you are ahead of the game, go to Alan's site and read, read, and read some more. VERY informative site for mobile installs. Especially the bonding, mounting, and cabling sections. But I recommend that you take the time to read through ALL of it. Much of it comes in handy at all times.
http://www.K0BG.com

Good luck and 73
Joe
Logged
N5MOA
Member

Posts: 1112




Ignore
« Reply #3 on: March 22, 2011, 08:11:51 PM »

My HI-Q 5/160RT covers 160-6. 6m sort of. Using it on 6m requires tuning, as mentioned, to a harmonic.

While I've made a few contacts on 6m with it, a vertical is not the best choice for 6m.

My shunt coils matches it on 160m, I tap it on another part of the shunt for 80m and up. I don't work 160m mobile much, so I rarely move the tap.

73, Tom
Logged
GOLDTR8
Member

Posts: 58




Ignore
« Reply #4 on: March 25, 2011, 05:16:21 PM »

Check out Scorpion Antennas.
Logged
KF7IUH
Member

Posts: 6




Ignore
« Reply #5 on: April 10, 2011, 08:47:52 PM »

I run the Hi-Q 4-160 on 6 meter i run a 2 foot whip above the coil. 160 I run the 2 foot extension the large egg beater then a full 102" whip tunes great on my 706. for everybody else I use a 5 foot whip above the coil. yes its a bit time consuming to change whips but it works for me.
Logged
W7STM
Member

Posts: 1




Ignore
« Reply #6 on: September 22, 2011, 08:18:52 AM »

Like Allan said 6 meters on a screwdriver enough said.

For HF there is also Larry's antennas  http://www.kj7u.com/home.php

Just wanted to add to your choices.
Logged
M6GOM
Member

Posts: 991




Ignore
« Reply #7 on: September 22, 2011, 12:20:22 PM »

The Tarheel Antennas - Little Tarheel HP = 7.0 - 54mhz & Little Tarheel II = 3.5 - 54mhz
http://www.tarheelantennas.com/


Sacrifice 6m band on the Little Tarheel II and change the whip for a 6ft one. It'll make a massive difference to the performance of the antenna.
Logged
N6AJR
Member

Posts: 9921




Ignore
« Reply #8 on: September 22, 2011, 12:29:30 PM »

Well yes and no.  I have a DK-3 that will tune 6-80 with a 60 inch whip.  I have a coil ( made by the folks at Knot who build the BB3 antenna) that I can screw on to get  160 meters, but it is big and heavy and can only be used when stationary. a full sized  CB whip will work better if you skip the 6 meter part.  so yes with 2 whips and an extra coil you can do 6 m to 160 meters but the band with on 80 and 160 is narrow and needs frequent retuning for even small frequency shifts.
Logged
W2RI
Member

Posts: 57




Ignore
« Reply #9 on: September 22, 2011, 03:51:44 PM »

Julius,

It depends on how much you want to spend. If you'll be spending a lot of time in your RV, you might want to consider getting the best you can for what will be your main shack, or close to it. In my case, I did as NASA and the US Marine Corps do, and went with a Hi-Q antenna form Charlie Gyenes (http://www.hiqantennas.com).

Charlie offers a range of antennas, with coil sizes ranging form 2.5 inches to 6 inches. The larger coil sizes offer greater efficiency and I have to tell you the 6/160 (6 inch coil, 6M-160M) antennas are spectacular. Just read the reviews here on eHam. I have a big pickup, and went with the 6/160 EX, a picture of which you can see on my QRZ page. This thing is a monster, but has performance to match. I get awesome reports even with just a 3 foot whip. When I am parked I usually add a cap hat or two and a 120 inch whip and have even more fun ! Cool

Some of Charlie's antennas are big, but on an RV you'll have plenty of room depending on where you decide to mount. I'd check out his site and the reviews here... Also check out the Yahoo mailing list to see what users think of the antennas. If you go with one of his products, you won't regret it! 
Logged
M6GOM
Member

Posts: 991




Ignore
« Reply #10 on: September 23, 2011, 04:21:02 AM »

I've just looked at Charlies website. What a tosser. Seriously that guy has more issues than I do.

I love the self contradicting part on one page:

"Special HF antennas for the US ARMY, Marines, Air Force and Homeland Security. In addition, many foreign military.

Who DOES the brand –X makes selling to?

That is right ONLY to you: HAMS and HAMS are more critical then some of the government buyers, YOU know better!"

Charlie, maybe thats why people aren't buying yours? And BTW Charlie, govt procurers, at least here in the UK, are known for going for something cheaper if it'll do the job over the best. And with transmitters they can just up the power to compensate for low performance.

You got the contracts because you were cheap Charlie, not necessarily the best....
Logged
W2RI
Member

Posts: 57




Ignore
« Reply #11 on: September 23, 2011, 09:59:06 AM »

I've just looked at Charlies website. What a tosser. Seriously that guy has more issues than I do.

Wow. What a constructive reply.
Quote
Charlie, maybe thats why people aren't buying yours? And BTW Charlie, govt procurers, at least here in the UK, are known for going for something cheaper if it'll do the job over the best. And with transmitters they can just up the power to compensate for low performance.

You got the contracts because you were cheap Charlie, not necessarily the best....
What makes you think that people aren't buying his antennas? As for your comment about government procurers, well, we know the history of the British space industry. Here in the US, NASA and US Special Forces aren't required to purchase junk.

More important than your opinion is the performance of Charlie's antennas, and the opinions and reviews of his customers. I know which opinions I value more highly.
Logged
K0BG
Member

Posts: 9885


WWW

Ignore
« Reply #12 on: September 23, 2011, 01:19:38 PM »

There are some very interesting comments here. Unfortunately, some of them are incorrect.

Fact 1). Larger coil diameters are not necessarily more efficient (higher Q). This is due to the fact that large diameter coils have a higher ESR, than smaller ones. This said, about optimal for 80 through 10 is about 3 inches. Part of the reason is basically the fact the L/D ratio changes as the inductive reactance changes, as does the ESR. Based on this, the Scorpion 680, the Predator, and the Tarheel 200A, are fairly close to optimal.

Fact 2). It is a very tough nut to crack, to cover 160 through 6 meters, even when changing whip lengths. It is all but impossible to design a coil for 160, and operating said coil on 6 meters, due to inherent self resonant problems. If you're going to operate 6 meter SSB, you want a horizontally polarized antenna, and you can't do that with a vertical.

Fact 3). The more metal mass in, and around the coil, the lower the Q. This is true of any antenna, but is especially critical in shortened mobile ones. Again, it is a self-resonant problem. Shortening the whip to compensate increases the ESR in the coil, and in some case will cause them to arc over.

Fact 4). For maximum efficiency, a large cap hat is a requirement, and said cap hat should be mounted atop a long mast, well above the top of the coil. Most cap hat users mount them too close, and some right on top the coil, which has an opposite effect.

Fact 5). All HF mobile antennas are a compromise. Some, however, are much more of a compromise than their owners would care to admit.
Logged

G8YMW
Member

Posts: 256




Ignore
« Reply #13 on: September 24, 2011, 03:10:06 PM »

Alan,
I dont know how 6 metres works on your side of the Pond but over here (Unless there is a contest on) 6 is deserted unless the band opens and as polarity goes out the window with Ionospheric Propagation then whether you are vertical or horizontal shouldnt matter.
Another point, a horizontal aerial, to perform at its optimum needs to be 1/2 wavelength  away from the car's bodywork or it tends to fire skywards.
OK a halo for 6, 10 feet above the car is going to cause no end of problems when on the move (PC Plod's attention, whacking bridges, overhead wires and trees)
I know this is 2 metres but demonstrates what I'm on about

http://www.qsl.net/vk3bjm/mobile.htm
Logged

73 de Tony
Sent by WW2 Royal Navy signal lamp
K0BG
Member

Posts: 9885


WWW

Ignore
« Reply #14 on: September 24, 2011, 03:21:58 PM »

I would tend to agree with your comments.

I have an M-Squared 6 meter halo on my Ridgeline. It is mounted to close to the body, but at the time I installed it, I don't want to mess with a fold over mount (I garage my vehicles). I do not have a way of measuring the TO, and EZNEC isn't much help, because I don't know what the actual ground losses are. This said, the difference between the 6 meter vertical (full 1.4 wave), and the halo is always 20 dB, and sometimes much more! So while the TO might be elevated, you sure wouldn't know it by the incoming signals.
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!