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: Mobile Hamstick type antenna  (Read 1438 times)
AB7JK
Member

Posts: 1




Ignore
« on: February 18, 2005, 11:05:47 PM »

Can a 20 meter Hamstick antenna be used on 17 or 15 meters by shortening the whip. If so 2-3 hamsticks could cover all bands. Anyone try this?
Logged
N3ZKP
Member

Posts: 2008




Ignore
« Reply #1 on: February 19, 2005, 08:32:13 PM »

While it may be possible, HamStick type antennas are pretty poor antennas in actual use. The 40m and 80m versions are useless. Much better is to invest in a real antenna system if you are serious about HF mobile.

Although much more expensive than HamSticks, any of the major brand motorised antennas will run rings around them and in mobiles, especially, antenna performance is everything.

Logged
WA5UHK
Member

Posts: 131




Ignore
« Reply #2 on: February 20, 2005, 05:51:15 AM »

This is bad news.  Last week I bought a 2mtr coliniar hamstick & a 20 mtr hamstick and I just finished welding a trailer receiver baseplate for them that will mount them at the back of my SUV.  Have you used a hamstick?  Is there anything I could do to make them usable?
Logged
N3ZKP
Member

Posts: 2008




Ignore
« Reply #3 on: February 20, 2005, 11:25:23 AM »

Yes, I have used HamSticks. 20m and up are usable. They are better than no antenna at all. 40m and 80m and almost dummy loads. At best, the HamSticks are several dB down from the motorized antennas; they are very lossy, and the typical installation with marginal grounds make them worse.

Their only attraction is they are cheap.

The 2m one I have no experience with. I use commercial grade Larsens for VHF/UHF.

Logged
AB7JK
Member

Posts: 1




Ignore
« Reply #4 on: February 20, 2005, 02:13:17 PM »

Well no one really amswered my question BTW I've had good success using hamsticks on 20 meters on up. Guess I'll try shortening the whip and see if the 20 meter tunes up on 17. Kim AB7JK
Logged
N3ZKP
Member

Posts: 2008




Ignore
« Reply #5 on: February 20, 2005, 06:01:46 PM »

Sorry about that ...

There was an article in Hints and Kinks in QST three or four years ago describing how to do this.

If my memory serves me, you cannot just shorten the whip. You must remove turns from the bottom winding, as well. Of course, this renders the 'stick useless on the original band.

Lon
Logged
AD5X
Member

Posts: 1428




Ignore
« Reply #6 on: February 21, 2005, 08:25:01 AM »

A Hamstick is easily used one band above the regular band by shortening the top whip.  I've used a 20 meter Hamstick on 17 meters, and a 15 meter Hamstick on 12 meters.  I use 1/8" diameter 3-foot brass rods for the new top whips (available from most hardware stores).  You can trim these as necessary.  I replaced the setscrews with #6 thumbscrews to make it easy to change the whips.  

Hamsticks are not bad antennas when used on 20 meters and above.  I agree that they are not very good on 40 meters and lower due to having poorer Q than bugcatcher or screwdriver antennas.

Finally, you will find that you need some sort of base matching for short antennas (if you don't, that means you probably have high ground losses, meaning your antenna system is pretty inefficient).  Generally, you can get by without base matching on 15 meters and above as the SWR is probably OK at resonance due to the higher radiation resistance of the antennas on those bands.

Phil - AD5X
Logged
WA5UHK
Member

Posts: 131




Ignore
« Reply #7 on: February 22, 2005, 05:52:43 AM »

Good info.

The only negative I have with the Hamstick so far is that it looks like a CB antenna.  I got by that one by applying for radio operator license plates.

I'll post my progress/opinion on it here as I get my mobile install up and running.
Logged
K8DIT
Member

Posts: 14




Ignore
« Reply #8 on: February 22, 2005, 06:45:59 AM »

No. By trying this you are further compromising a compromised antenna. You are certainly free to do this but what's the point? Optimizing any energy you want to radiate is a matter of design. In good condx. a properly installed hamstick will do nicely with 100 watts. Efficiency is already compromised by several factors just being mobile. Matching impedance alone does not mean much in terms of performance. The only way to demostrate this is by playing with various mobile antennas over a period of years. Cutting corners will lead to frustration. Doing it right will build confidence from success.
Logged
WB6BYU
Member

Posts: 13234




Ignore
« Reply #9 on: February 22, 2005, 03:44:57 PM »

I'd think you would be better off using a longer whip
and trying to use the hamstick on the next LOWER band
instead.  In this case, the longer whip should have a
higher radiation resistance, and so higher radiation
efficiency for a given ground loss resistance.

But the key factor here is the self-resonant frequency of
the loading coil.  You might squeek a 20m coil up to 17,
but probably not to 15m because the parasitic capacitance
across the coil with no whip section installed will be
enough to keep the resonant frequency below that.  I'm
not familiar enough with the hamsticks to know where they
will actually tune, but from comments I've heard even one
WARC band up may be a stretch.

The quick test is to remove the whip (or perhaps replace
it with a few inches of wire) and find the resonant
frequency with a dip meter or SWR analyzer.  If that
doesn't get you up to the desired band, trimming the
whip won't help.

As the operating frequency approaches the self-resonant
frequency of the coil, the losses increase due to the
circulating currents.  (Of course, the higher losses
will give a wider SWR bandwidth, a feature that one of
the older mobile whips appeared to use intentionally
on 75m.)  So it might work with some bands, but at
reduced efficiency.
Logged
AB7JK
Member

Posts: 1




Ignore
« Reply #10 on: February 23, 2005, 06:20:52 PM »

Thanks for all the useful information - something to think about. AB7JK
Logged
W8CAR
Member

Posts: 109


WWW

Ignore
« Reply #11 on: March 02, 2005, 12:22:54 PM »

I would agree that the Hamstick can be used on other bands by shortening or lengthing the stinger. I have a capacitance hat made of three pieces of wire that allows the 75 meter stick to tune to the bottom of 80 meters. I also use a base loading coil for a better match to the coax. As for them being not good-I disagree. In the Ohio QSO party (in August) mobile with my Icom 706 we worked several HA stations on 40 CW and many EU on 20 CW. Like all mobile antennas they are a compromise but work very well in my experience.
Logged
W8CAR
Member

Posts: 109


WWW

Ignore
« Reply #12 on: March 02, 2005, 03:54:25 PM »

I would agree that the Hamstick can be used on other bands by shortening or lengthing the stinger. I have a capacitance hat made of three pieces of wire that allows the 75 meter stick to tune to the bottom of 80 meters. I also use a base loading coil for a better match to the coax. As for them being not good-I disagree. In the Ohio QSO party (in August) mobile with my Icom 706 we worked several HA stations on 40 CW and many EU on 20 CW. Like all mobile antennas they are a compromise but work very well in my experience.
Logged
KE4SKY
Member

Posts: 1045


WWW

Ignore
« Reply #13 on: March 04, 2005, 05:52:08 AM »

It should work, by shorting for higher freqs but you will have to tinker with it.  While a hamstick may not be the best radiator, they are rugged and inexpensive.  With the amount of tree bashing I do off road I don't want to tear up an expensive antenna.  The hamsticks are throw-away, but functional.  

I use a 75 meter Pro-Am hamstick knockoff on 60 meters.  I optimized for 5371.5 KHz by shortening the 48" "stinger" down to 11" and adjusting protrusion below the set screw for the best VSWR in my mobile install.  My antenna is mounted up high on the vehicle and I get good reports, a full S-unit better than the Hustler.
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!