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eHam Forums => Mobile Ham => Topic started by: AD5GX on March 02, 2003, 08:34:56 PM



Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: AD5GX on March 02, 2003, 08:34:56 PM
All,
As I prepare to go mobile HF, I have chosen the rig: 706MarkIIG.  Now I come to the antenna.

I am deciding between an AH-4 tuned 102" whip or a Tarheel Automatically controlled screwdriver antenna.  The AH-4 combo will probably run around $300 whereas the Tarheel combo will get to $700+!

Can I reasonbly expect enough of a performance difference to warrant the extra cash?  I'm willing to spend it if it means I'll get enough extra enjoyment from the set up.

Thanks and 73s!

Matt, AD5GX


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: N8EMR on March 03, 2003, 08:14:18 AM
I have the 706, ah4 and whip. The 102" whip, actually 108" when you figure in the spring will provide a good signal on 10,12,15,17 and 20m. It will tune on 40 and radiate. It will tune on 80m but will not radiate worth a darn.

So where do you ant to operate your mobile? The screwdrivers is hands down a better antenna on 80/40 and probably 20m. both antennas will give you similar signal on 10,12,15 and 17m.

The 706/ah4/whip combo gives you a one touch tune on a freq, the screwdriver a bit more work.

The whip mounting machanics will be easier than the screwdriver.

Overall, what do you want to do with the radio, what freq, what ease of use factors need to be figured in?

I ended up going with a 706/ah4 and a 16ft whip for my mobile. That offered better 40m signals and a usable 75/80m signal for the local nets I check into.


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: K0BG on March 03, 2003, 09:27:37 AM
You might be interested in reading some articles I wrote here on eham.net. They are:

http://www.eham.net/articles/4407
http://www.eham.net/articles/4424
http://www.eham.net/articles/4425
http://www.eham.net/articles/4623

Even the best of screwdrivers (or just about any other antenna you can name) won't perform very well on 160 and 80; they're just to short.

I like the AH-4 because it offers nearly instant band QSY and because I use a 20 meter resonant antenna with it, it performs very well on 40. It is just bearly passible on 80.

Alan, KØBG


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: AD5GX on March 03, 2003, 06:40:00 PM
Thanks for the info!  I'd like to do some on 40 (mostly for the relatively local ragchews) and higher, so I think the whip/tuner would work o.k.  I still have the chew it over with the XYL!  I think she would like the look of the whip over the look of the screwdriver.  

I think the benefit of starting with the whip is it is a relatively low cost of entry to mobile hamming.  If I really like it and want to get more on 40/80 I can upgrade to the screwdriver at a future Christmas.

And the AH-4 has secondary possibilities for portable uses as well.

I'm still not 100% decided but your input and the articles helped considerably.  I have 3 good days planned in the future dedicated to addressing vehicle noise issues!


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: WU3U on March 18, 2003, 12:59:17 PM
While I cannot speak with the technical authority of K0BG on the issue of mobile antennas, I can relate my experiences with the screwdriver antenna.

Mine is a High Sierra HS 1500.

I am currently working on becoming perhaps the first-ever HF mobilier to earn the Five Band WAS since that award was first offered in 1970.

I have WAS on 40, 20, 15, and 10 meters with 47 states logged on 80 meters - all done with the High Sierra HS 1500 Screwdriver, all QSOs at 100 watts out, all CW, and all completed not more than 50 air miles apart as per WAS rules.

It is true that any practical mobile antenna will be inefficient on 40 and 80 meters, but I found that with the High Sierra, I could work almost anything I could hear on 80 meters and all other bands as well.  

Many of my 80 meter (and all other) contacts toward Five Band WAS were made during contests in heavy QRM so the screwdriver, even though inherently inefficient on the low bands - is still an excellent practical antenna for mobile applications, its natural inefficiency on low bands notwithstanding.

This assumes, of course, that the antenna is well grounded to the frame of the vehicle - in my case it's a 2001 Toyota Tacoma pickup truck which does provide an excellent ground, or in the case of the low bands, an excellent capacitive coupling to actual ground.

I think that for all round band coverage consistent with a good to excellent signal as mobile antennas go,
along with the ability to tune the antenna remotely,  from within the vehicle, the screwdriver is hard to beat.  

There are several excellent choices, High Sierra being one of them.

I have used two other types of mobile antenna:  An Outbacker Perth Plus and a Hustler System with coils for each band.

Screwdrivers are, however, quite large and bulky for a mobile antenna and sometimes require a more complicated mounting scheme, as they need a very secure and heavy mount.

Still, to get the most out of your rig with a pretty darned good signal as mobiles go on 80 (however inefficient the antenna is....remember there is "inefficient" and "doesn't do a danged thing!) and an often excellent signal on 40, 20, 15, and 10 meters, give one of the screwdriver designs some serious consideration.

73

Tim
N8LXR/M


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: KA5S on April 03, 2003, 10:08:07 PM
I used an AH2 and whip for a few years. A 102 inch whip on the roof with the tuner in the back worked very well on 30 meters and higher HF bands, but I still needed a more efficient antenna (ended up with a Texas Bug Catcher) on its own mount for 40 and 80. I suspect an AH4 will work poorly enough on 40 that you'd find a Hustler noticeably superior in use.

At present I am using TWO screwdrivers, one Superantennas MP3 for 7 MHz and up, and one DK3 with an extra loading coil for 3 through about 7 MHz. They're not as efficient as a Bug Catcher, but they sure are convenient.

Cortland


Title: Screwdriver -vs- tuned 102" whip Antenna
Post by: KA5S on April 03, 2003, 10:08:23 PM
I used an AH2 and whip for a few years. A 102 inch whip on the roof with the tuner in the back worked very well on 30 meters and higher HF bands, but I still needed a more efficient antenna (ended up with a Texas Bug Catcher) on its own mount for 40 and 80. I suspect an AH4 will work poorly enough on 40 that you'd find a Hustler noticeably superior in use.

At present I am using TWO screwdrivers, one Superantennas MP3 for 7 MHz and up, and one DK3 with an extra loading coil for 3 through about 7 MHz. They're not as efficient as a Bug Catcher, but they sure are convenient.

Cortland