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Thinking Mobile HF 12 - June - 2010

Posted by k9zw in K9ZW, K9ZW Just Rambled.
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With all the life changes the likelihood of more road time during which I might be able to do HF contacts is here!

Now the big decision – to do an HF Install or to do a “Virtual HF Over Internet Link” to my home station?

On the plus of a real install is that the contacts really count as mobile, and operations are independent of the net or home shack. These types of installations are not inexpensive and on a miles basis I am within 18 months of a new vehicle – meaning the install would be pulled & moved fairly quickly.

The idea of an over-the-internet link to my SDR setup has the advantages of lower initial costs, making use of a decent home station and little hardware to purchase. It would also be VERY portable and easy to move to the next vehicle. On the flip side it would require a monthly net subscription, isn’t true Mobile operations and requires me to leave my home station “hot” to operate. It is also net coverage dependent.

I’m still thinking through this one and welcome your thoughts.

73

Steve
K9ZW

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Comments»

1. Ma - 13 - June - 2010

the thoughts are obvious but require you to decide what is your goal “true mobile” contacts or contacts while you happen to be mobile. one or the other will decide the issue

personaly Id choose the virtual mobile myself but then I want to make more contacts and don’t care that much how i get them

2. Jeremy KB7QOA - 14 - June - 2010

A mobile setup doesn’t have to be expensive, it just depends on what you want to do. A Yaesu FT-857D and a screwdriver antenna would get you on 80-6 on HF, and you’d have all-mode 2 and 440 with you as well. $900 for the radio and $600 for the full High Sierra antenna package, and you’re up and running.

3. Jeremy KB7QOA - 14 - June - 2010

Hit the button too early… I wanted to add that it may not be a SDR with all the bells and whistles, but do you really want that when operating mobile? Now if you’re talking of wanting a more elaborate station when camping with an RV that is one thing, but when you say “driving” and “mobile” together I’m thinking you’re wanting to operate while cruising down the road. In that case, the simpler the better, and the less you need to touch to change repeaters or change to your favorite HF frequency, the safer you’ll be.

The other thing to keep in mind is with a simple setup, when it comes time to move to a new vehicle, you have your power leads, coax, antenna control leads, and you’re done. This of course assumes you don’t have to do any extra grounding and/or panel bonding, but this is a potential factor no matter what vehicle or radios you use.

As hams I think we all have the tendency to over-engineer and shoot for the maximum bells and whistles. In my opinion mobile operations are where we really need to take a step back and go for the simple setup so we can keep our eyes on the road. Right now for the most part we’re pretty universally excepted from the anti-cell phone laws. Let’s do our part to keep it that way.

4. XE1NW - 15 - June - 2010

I am also pondering the same issue. Driving to work and taking kids to school adds up to about an hour and a half on the car each day. I currently have a VHF and UHF rig in the car, however, HF is much more interesting. I had not considered the possibility of “Virtual HF Over Internet Link”. This option looks interesting, but it is not very attractive because I would need to pay a monthly data plan for my mobile phone (in México it is very expensive). Also, I do not like the idea of leaving the rig connected to the antennas, since where I live lighting storms are frequent. For these reasons, I think I will go for a FT-857D, a couple (40m and 10m) Hamstick antennas and a K400C Diamont mount.

5. N9FDE - 15 - June - 2010

Hi, Very interesting question you have. Well, I have been running HF mobile for a number of years and I love it. A great way to pass the time as you travel and it’s a ton of fun. As soon as you say “mobile” with your call sign everyone wants to talk to you. I say just go for the “real” HF mobile set up. I run an IC-7000 Icom and the Hi-Sierra 1800 screwdriver, one thing I added to the antenna was was a motorized shunt . I had the guy from Predator antenna make it for me it makes a world of difference. One of the main things to remember during install is “Ground Ground Ground” make sure everything is bonded very well, ie: body to frame (don’t matter if it uni-body or not) bond it, the doors ,hood , trunk lid, everything. This really matters especially on 40 meters. As far as the rig goes just go with the 7000 it’s a rig that’s made for mobile use it has a de-tachable face which is very small and takes no room to install. Also, the 7000 has the most features of any rig out there for this task, It’s like having a 756 PRO III in a small box. New or used there a great buy for the price and you’ll be happy with it. The menues are right at your finger tips and easy to use (meaning you don’t need the manual there all the time). As I ride along in the mobile and talk I get great signal reports from everyone and they can’t beleave that I am mobile. Just follow the main rule of HF mobile (ground ground ground) and youll be fine. Also, like I said before the Shunt coil on the HF mobile is very important. So don’t skimp, you can either make one with switched variable taps for each band or go the what I did and get a motorized version. I can tune my ant. on everyband to absoloutly flat SWR and as we all know there is no substitute for a resonate antenna. Most of all have fun with it. Beleave me once you go HF mobile and do it right you’ll never regret it……

Bill

6. bill KG4ZQZ - 15 - June - 2010

have had an ATAS-120A and FT-857 in my F-150 for the past six years, and the combo has worked flawlessly; i did add an MFJ 4416, but that’s only because my truck battery is coming up on seven years (will most likely have to replace soon); i routinely chat w/S. American/Caribbean ops, but have also had contacts w/mid-East ops during openings…

7. Kuby, N6JSX - 20 - June - 2010

de N6JSX/Mobile 8, there is more to consider before diving into the mobile world, like the secure mounting of the screwdriver antenna to the vehicle. (Screwdriver is the only way to go!) Most new vehicles do not have accessible or sound metal bumpers, I used the spare tire mount on my SUV rear door. But external spare tires are becoming history and disappearing.

See http://groups.yahoo.com/group/RDF-USA/files/Technical/

Also the DC power run to the rig needs to be at least AWG10 (8 is better) wire!

Then what radio to install – the best mobile by far is the IC-7000 beats prior installs of IC-706mk2g, IC-706, TS-430, Atlas-210x.

Going mobile is fun but takes some work and on leased vehicles very tricky. Not all screwdrivers are created equal too!

8. Kuby, N6JSX - 20 - June - 2010

Oh another neat item about going IC-7000, it is high power 2m/430-440 all modes. So you can use for repeaters or SSB (with a M2 Loop). The IC-7000 has the remote head capability for those smaller dash mounting areas too, which also allows you to add extra cooling fans on the main body when mounting in the rear of the vehicle and also keeps the coax runs short. Yes, rag chewing will get that very small radio hot. 7K has HF and VHF antenna ports.

What makes the IC-7000 the best mobile rig ever, is variable IF DSP, variable noise blanker, pre-amp, variable filter skirts and more. I can almost knock out my intermittent windshield wiper motor RFI with the 7K that the 706mk2g w/audio DSP could never touch. 7K is a 746Pro (my base rig) with a color display.

9. Kuby, N6JSX - 20 - June - 2010

After the rig comes the other #1 item “screwdriver.” BEWARE of all the sales hype and down right BS…. First the screwdriver is a tunable compromise to a 1/4wave length antenna. So inherently it is already inefficient. Now add to to this compromise the limited ground counterpoise you can use based on the amount of vehicle metal (which you have no control over) and your antenna ground attachment quality.

You want to install the most efficient screwdriver possible. This rules out all antennas using ‘toroid’ loading. [Your radio may love the 50 ohms of the toroid but the energy loss is crippling! Plus you are loosing RX signal due to the toroid consuming some of it!!!] L/C coupling is better than a toroid but is still inefficient.

I run a KJ7U Larry’s Antenna http://www.kj7u.com/ , it is a direct connect using NO coupling system. This is the only one that can do 6-160m, with the right size whip (I use a 5′ whip). But this antenna does have quirks/workmanship issues that require modification (I can cover later if interested}.

My SUV often talks to Europe with only slight openings and anywhere USA most any time, usually the other end of the QSO is surprised I’m a mobile…. When / >IF< the bands ever return I talk to Europe when I want on 17m and with WI homeboys on 3913.

N6JSX/8 Ohio (my youth home was Manitowoc)

10. N9FDE - 27 - August - 2010

Just for everyone’s info that reads this. I checked into the KJ7U Larry’s Antenna, All I have to say is steer clear my friends. This thing is a pile of junk and looks like it was constructed from junk that was laying around the house. The workmanship it something that looks like a 10 year old did. If your thinking of buying a screwdriver type mobile antenna, spend your hard earned cash on one of the main stream versions.

11. Kuby, N6JSX - 27 - August - 2010

As I previously noted the KJ7U Larry’s screwdriver has problems and workmanship is poor. I’ve had to do some major rework and modifications to make the antenna dependable/work.
1. the custom plastic top plate that holds the rubber WX sleeve is junk/broke in a year. I found a 2″ PVC end cap to be far more durable.
2. the coil lead screw easily slips out of the drill chuck bit rendering the antenna unusable, I HAD TO weld the lead screw to the chuck to solve this problem.
3. the motor noise suppresion capacitors (ground side) solder connections fall off the motor housing, proper solder techniques/flux fixed this.
4. the motor wire lead is way to short forcing external vehicle connections in the WX. Also the internal motor drive wires were spliced with different size wires. I replaced the whole harness with longer 12AWG wires that allows connections inside my vehicle – out of the WX!
5. the drill motor has a 3-position clutch setting, raising and lowering the coil changed the clutch from max-to-min and back, I glued this down to min-slip setting.
6. no turns magnet, installed a rare-earth magnet at the chuck/lead screw.
7. no turns counting switches, installed three reed switches 120degrees apart on outside of aluminum tub – put reed switches inside brass sleeves to protect. But you need to insure proper switch location for consistent magnet activation then wire all in parallel.
8. taking the antenna apart is not hard (when new) but putting it back together is very very hard – aligning the three motor retaining holes is almost impossible. The Phillips screw heads are easily stripped when the steel screw weathers in the aluminum threaded hole!

I’d change screwdrivers but I got this one to work well, it just took me 5yrs of trial-n-error with troubleshooting/modifying. Also many of the competition have toroid/LC networks that cripple efficiencies!

Just recently the screwdriver controller I was using failed (suspect a near lightening ESD hit), the company has gone out of business and will not support/supply a schematics but still retains its web site as active.?!@#$% http://www.thescrewdriver.com/

I’m replacing the controller with the MFJ-1922B and found the data sheet to be grossly inadequate; no info on how the counter sensor circuit operates? When contacting MFJ they dumped me off to Ameritron, (they were far more helpful) and told me to look at SDC-103. I now have to change/modify the vehicle cable to allow the turn counter to work due to the stupid required 2-wire MFJ circuitry that requires the controller to put 5VDC out to the switches for toggle count, the other controller used a simple 1-wire pull-down method for toggle counting. The MFJ is missing a control button (they told me how to install it). Further analysis has the same issue with MFJ/SDC in having NO ESD filtering on the I/O lines nor fusing.

So you better be a real EE tech to go mobile, as the cookie cutter plug-n-play is just not that simple or reasonably available. Good antenna installation is key to HF mobile fun!

12. AK4BQ - 14 - February - 2011

Knowledge is power – research is everything


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