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] 2 3 Next   Go Down
  Print  
Author Topic: HF mobile antennas that handle power  (Read 6740 times)
N7QX
Member

Posts: 21




Ignore
« on: February 22, 2011, 04:01:33 PM »

Thinking about returning to full time RVing again and would like to be able to use 80-10 meter bands with amplified power.  Used to use a Perth Outbacker but that only rated at 150W out.  Any recommandations on mobile hf antennas with higher power ratings?  Thanks
Logged
W5DXP
Member

Posts: 3583


WWW

Ignore
« Reply #1 on: February 22, 2011, 05:41:11 PM »

Any recommandations on mobile hf antennas with higher power ratings?

The High Sierra screwdriver antenna, HS-1800, is rated at 1000 watts PEP.
--
73, Cecil, w5dxp.com
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
N5UD
Member

Posts: 800




Ignore
« Reply #2 on: February 22, 2011, 10:46:35 PM »

You might try Tarheel, HI-Q, and Scorpion as they all have kilowatt models.

Dave N5UD
Logged
WX7G
Member

Posts: 6049




Ignore
« Reply #3 on: February 23, 2011, 05:45:54 AM »

I have a Tarheel 200A HP rated at 1500 watts PEP. I use it everyday at 1200 watts on CW at the house. The counterpoise is quite good - less than 10 ohms - and this results in maximum antenna current and maximum stress. It has never given me a problem in two years of heavy use.
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #4 on: February 23, 2011, 03:48:32 PM »

I have a Scorpion 680 mounted on my Honda Ridgeline (photos of it are on my web site). At my remote transmitter site (on 6 mile hill, west of Roswell, on highway 70), I have an Alpha 77Sx (two 8877s), with the big transformer. It loafs at 1,500 out dead carrier. Fed to the antenna, through about 50 feet of RG213, after about 2 minutes, on 20 meters, on a dead band, the antenna's whip (17-7 SS) was a bit warm. The shunt matching coil, however, (enameled #14 wire) got hot enough to turn a rather dark bronze color, prompting me to change it to #12, but nothing else bad happened.

My old HiQ580, under the same conditions, lasted about 25 seconds before the lexan coil assembly melted due to coil arcing.

Make your own conclusions.

Logged

N5UD
Member

Posts: 800




Ignore
« Reply #5 on: February 23, 2011, 10:09:49 PM »

Well Alan you got my curiosity up. Why are you running a two Alpha into a screwdriver antenna ?

I recall when those first came out, it was usually just the big DX contest stations that had them.

Simple (poor) me always thought the one holer was plenty to make any DX QSO.

Dave

N5UD
Logged
WX7G
Member

Posts: 6049




Ignore
« Reply #6 on: February 25, 2011, 05:56:44 AM »

The Perth Outbacker: The world's most expensive Hamstick.
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #7 on: February 25, 2011, 07:10:48 AM »

Dave, N5UD, although I have owned two Alpha 77s in the past, I have long since sold both of them. The amp in question does not belong to me. It was just a test on my part to see if the antennas could take their rated power. Most can't. You should have been there when I tested an Ameritron SDA-100! I think the SDA stands for Smoke Developing Antenna.

As for the Outbacker, David, WX7G, I agree. It is also a dummy load on a stick, and a Kenwood TS-480Hx, is capable of destroying one.
Logged

W5DXP
Member

Posts: 3583


WWW

Ignore
« Reply #8 on: February 25, 2011, 07:11:04 AM »

The Perth Outbacker: The world's most expensive Hamstick.

Actually, in the 75m shootouts, the Outbacker measured 3 dB better than a 75m hamstick and only  9 dB down Smiley from the top-rated bugcatchers/screwdrivers. For every 10 watts radiated by a top-rated screwdriver antenna, the Outbacker radiates 1.25 watts.
--
73, Cecil, w5dxp.com
« Last Edit: February 25, 2011, 07:15:05 AM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #9 on: February 25, 2011, 07:06:33 PM »

Cecil, it is still a dummy load on a stick.
Logged

WX7G
Member

Posts: 6049




Ignore
« Reply #10 on: February 26, 2011, 03:16:30 AM »

Alan's test was key down at 1500 watts. Unless someone is running RTTY they will never do such a thing.

The SDA-100 is marketed by Ameritron. Does Tarheel make it?

As I said I run a Tarheel 200A HP at 1200 watts on CW everyday without a problem. So I think that for the motor home a Tarheel high power antenna will hold up to an amp.
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #11 on: February 26, 2011, 08:02:50 AM »

Actually, I used an iMate which has a built in pulser. The wattmeter set on peak was right at 1,500 watts, but the average was not quite 700 using an older model WM1 Mirage.

Just for the record. My SG500 will dead carrier at 550 watts on 20 meters (engine running of course), just before the automatic attenuator kicks in (≈65 watts drive). A 20 meter Ameritron hamstick knockoff will fail within 30 seconds at this power level.
Logged

WX7G
Member

Posts: 6049




Ignore
« Reply #12 on: February 26, 2011, 03:21:52 PM »

So who makes the Ameritron SDA-100? The ad copy is from Tarheel yet I don't see it at the Tarheel website. HRO shows it being made by Tarheel. I've wondered if the SDA-100 is the same as the Tarheel 100A.

Do you mean the "HF Stick"from MFJ burned up? Ameritron does not sell a Hamstick-like antenna.

I've run a 40 meter Hamstick at 400 watts in CW mode (on off keying) for months without any evidence of heating. A shortened Hamstick-like antenna from MFJ did burn off the heatshrink tubing but kept on running.
Logged
K0BG
Member

Posts: 9863


WWW

Ignore
« Reply #13 on: February 27, 2011, 09:10:47 AM »

MFJs hamsticks are called HamTenna®. The 20 meter model number is MFJ-1620T.

I suspect Tarheel makes the MFJ. I've had two. One was given to me because the motor gave out, and the motor bracket is pop riveted in. It was fixable, but not worth the effort. That's the one I smoked. The other was band new , and part of a trade. I gave it to a friend in Kerrville, TX to replace a very old High Sierra. Its problem was the contact ring assembly, a major drawback they have never redesigned.

The SDA-100 has two drawbacks. The mounting is actually a threaded 1 inch, standard pipe stem. They make two or three different ones for the antenna. It screws into the plastic bottom insulator. In very cold climes, it tends to crack easily, especially if it is tightened down too much. It also leads to incorrect mounting schemes. I saw one at the last Midland, TX hamfest, mounted atop a 10 foot long piece of pipe. In other words, no ground plane under it.

The other is the way the matching coil attaches. Unlike the Tarheel, the shunt matching coil is mounted in the clear. There are two threaded studs it attaches to, which also serve as the coax attachment points. The bottom one is where the coax shield connects. That stud is tightened through the insulator into the mounting pipe. The connection isn't all that good to start with, and loosens over time due to flexing with obvious results. The upper connection where the coax center connects, goes through the mast of the antenna. There is a warning in the manual about not tightening the screw clear in, yet it is their biggest field support issue. When it is screwed in too far, it contacts the pipe stem which shorts out the coax. It just isn't that robust of a system.
Logged

AF6WI
Member

Posts: 105


WWW

Ignore
« Reply #14 on: February 27, 2011, 11:12:41 AM »

> My old HiQ580, under the same conditions, lasted about
> 25 seconds before the lexan coil assembly melted due to coil arcing.

VIDEO! I want to see the video of that!
Logged
Pages: [1] 2 3 Next   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!