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Author Topic: Hf antenna's Screwdriver vs Electronic Help  (Read 5970 times)
VK2ICJ
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Posts: 91




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« on: March 28, 2012, 04:17:20 AM »

G'Day all.

I'm about to embark on a month long trip to the Simpson Desert in the Middle of Australia.  We have a 4wd HF network here and I also do Ham inbetween the 4wd nets.  I run a Codan HF radio and up till last Sunday arvo a Codan 9350 HF Screwdriver antenna.  Long story short I melted it.  I need a replacement for 2 to 30mhz.  I can get a new 9350 posted and for about the same cost I can get a new TET Emtron auto switching antenna.  Now I know the brands are not ones you hear about often in the U.States so no worries there but the technology is different as well.  There is the mechanical screwdriver design and the electronic switching.  According to the dealer the electronic switching is heaps faster to tune (not that the 9350 was slow) and can tune a better variety of antennas (not that my whip will be changed) but is not as sensitive on receive as the screwdriver 9350 (he said 10% or so less not much,,, in my book that is a lot) especially on scan .  In general  what is your opinions on the "new" crop of automatic antenna tuners for mobile use that are totally electronic vs the screwdriver types.   Just for reference  here are the 2 antennas.

http://www.tet-emtron.com/product-p/rt-360.htm

http://www.codan.com.au/Portals/0/publications/hfradio/9350M_data.pdf

Cheers

Chris

73 de vk2icj r
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K0BG
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« Reply #1 on: March 28, 2012, 09:32:43 AM »

Both the Codan, and Emtron are base loaded antennas. They're passible, but there are much better ways to go. Any decent quality screwdriver antenna will out perform either one. Most screwdrivers will tune quicker than the Codan, but much slower than the Emtron as it isn't much more that an auto-coupler with a radiating element attached.

Scorpion, and Tarheel both ship to VK-land, as do others.

You might want to visit my web site for more ideas.
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KH6AQ
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« Reply #2 on: March 28, 2012, 11:23:29 AM »

Chris, your question is which of the two antennas is best:

To you the Codan is a known quantity. As long as you know why you melted it and avoid melting the new one I think that is the antenna to get.

The TET is a new design and are the bugs worked out? The loading inductors probably have more loss than the Codan loading coil and so TET, given the same total length, will not perform as well.
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VK2ICJ
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Posts: 91




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« Reply #3 on: March 28, 2012, 12:17:13 PM »

Thank you fellas

Yes it was my mistake that caused the melting.  I know what I did and will not do it again (crossed second battery wires and ran full current through the radio and antenna) .  It has been a very costly mistake.  At any rate I leave for the Outback a week from tomorrow so my time is very limited.  I had a look at Alan's site,, very informative.  I even have 2 Tarheel dealers in Sydney that I could go to.  I am concerned about the interface to the Codan 9360 though and the Tarheel's durability in the outback and 1000 kilometers of the Simpson Desert including corrugations and mulga scrub.  The one button on the face of the Codan's head unit which tunes either of antenna's I mention does make the process easy and the antenna feeds back to the radio when it is ready which is nice to know that it is tuned without an SWR meter on the Codan.  I was leaning towards the Codan as it is a known factor to me.  If I had more time to experiment I think I like the Tarheel or Scorpion Idea,, but I would need to verify that they work with my radio and that they are up to the task of the outback.\

Chris
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VK2ICJ
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Posts: 91




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« Reply #4 on: March 28, 2012, 03:17:51 PM »

I just got off the phone with my local Tarheel dealer who advised that the Tarheel is a much better performer than the 9350 but sadly not built for the desert conditions I encounter.  He was quite certain that I would be happy with the performance and the quality of the build but they just were not up to 1000's of kilometers offroad on corrugations.  (not much is)

Thank you any way Allan (and others) as I believe the screwdriver is the better way to go.

Chris

de vk2icj r
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K0BG
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« Reply #5 on: March 28, 2012, 04:28:04 PM »

I'm perhaps a bit biased, but if ruggedness is what you want, then look at the Scorpion. It is not cheap, but it isn't all that much more than the Codan.

If you do end up buying a Tarheel, the 200A is about the best one. The only problem with operating one off-road, is the mounting scheme. Under heavy use, the mast assembly fatigues right at the top of the U mounting bracket, causing the antenna to fail catastrophically. Since the insulator isn't all that robust, opening up the hole, and using a piece of even PVC an inch or two long, in place of the plastic ring, will prolong the life considerably.
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VK2ICJ
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Posts: 91




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« Reply #6 on: March 29, 2012, 03:52:21 AM »

Our roads are not exactly smooth out here.   Wink  If I had some time to really look at the scorpion and have a go I just might.  But I've got to leave week this Friday and will be gone for 3 weeks. This is not to bad but gives you an idea of what I mean by 1000's of kilometers of corrugations

http://youtu.be/Jf4ilmLsw5g

I need something I can trust as out there sometimes radio is more than just fun it is a lifeline.  But maybe next year I will give one a go.  I plan on operating each night to log some QSO's from the Desert so that should be fun.

73

Chris
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M6GOM
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« Reply #7 on: March 29, 2012, 10:23:38 AM »

How much power do you need to run? I would look at something like a SGC230 antenna coupler and put the longest whip on it you can. Almost instant tune up on all bands 1.8MHz to 30MHz.
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VK2ICJ
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Posts: 91




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« Reply #8 on: March 29, 2012, 05:27:00 PM »

The rig is 125 watts PEP so that is about 80 out the back on SSB.  I can't use CW on this rig (yet) as there is no port on the back for it.
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M6GOM
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« Reply #9 on: April 01, 2012, 01:55:38 PM »

Have a look at the SGC230 then. It'll run 200W PEP/80W continuous. The advantage of running what I suggested is all you have is a whip, no coils etc to get broken and when parked up you could take out the whip and connect a long wire up to it. No tuning boxes required, just a low amp 12V feed. When you change band all you need to do is TX and it tunes up, recalling in milliseconds from memory first or taking a second or two if having to retune from scratch.
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VK2ICJ
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Posts: 91




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« Reply #10 on: April 03, 2012, 02:54:11 PM »

Thank you M6GOM and everyone else for their input.  I will experiment through the year and try some of these ideas out.  I went with the Codan Screwdriver as that is a known variable to me and I could get in the short time required before our trip.  We leave on Friday hi hi.  We will be driving almost 7000 kilometers with roughly 4500 of that offroad.   If anyone is remotely interested in following us here is the link to our GPS tracker

http://spotwalla.com/tripViewer.php?id=440b4f78deb168f78&p=jeep

I hope to make some contacts on the trip

73

Chris
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