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Author Topic: 10 /11 meters: whip antenna w/ artificial ground  (Read 5562 times)
KB2GBV
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Posts: 5




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« on: March 02, 2006, 02:47:50 PM »

Greetings-

I *really* wish I had found this forum before I made my purchases. But here we are.

Situation is this: I'm doing a 4-5 month cross-country cycling trip in May; 5000+ miles on a recumbent trike equipped with a solar power center.  It's been several years since I've been on the air, but once I decided that I wanted to bring a CB (for NOAA weather alerts and for yelling at passing trucks who think it amusing to "give me a scare"), I decided to see what I could bring along in the  Way of Ham, given my long-standing yet paltry license class.

Long story medium: MFJ 9410 10-meter radio for SSB and an MFJ 1644 artificial ground/whip antenna tuner.  My thinking was: 1 telescoping antenna with an artificial ground, plus an antenna switch, and I could use the same antenna/tuner combination for 10-meter SSB and CB. Space, weight, and "complication" are primary considerations.

I've already got the equipment, now I need to get the most out of it. My questions:

1) Keep the somewhat chintzy MFJ telescoping antenna that came with the 1644, or is there something that can squeeze out of few more dB on 10 meters and 11 meters?

2) Counterpoise wire: trim to center somewhere between 10 and 11 meters? If so: 1/4 wave, 1/2, etc. I can build a dipole easily enought, but I'm new to the whole vertical antenna thing.

Any advice is much appreciated.

Thanks,

Ian
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WB2WIK
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« Reply #1 on: March 02, 2006, 04:16:16 PM »

Not sure why you'd bother with the artificial ground, while in motion on the bike.  The bike frame is presumably metal (aluminum, titanium, something conductive) and if you achieve a good electrical bond to that frame, it ought to be perfectly adequate for 10m/11m use, without any "artificial ground."

The MFJ 10m rig actually sounds very good on the air; however, its frequency calibration accuracy isn't good at all, and with a Novice license you must be really careful to stay within 28.300 to 28.500 MHz.  Hard to do with the crude dial calibrations on the MFJ, so this may not have been the best choice.

Considering where we are in the sunspot cycle (we are at "zero" sunspots, meaning 10m propagation is very limited most of the time), 10m itself isn't a great choice for actually making any contacts.  However, during the summer months, with the long days, there should be some openings -- not nearly what occurs during a sunspot cycle peak (like 1999-2001) but, at least something.  At this point in the cycle, 10m is very much a "daytime" band and there's very rarely any kind of propagation at night, unless you happen to catch some sporadic-E.

If I were taking such a long trip, I'd want to be on 40 meters, probably.  A lot more activity, and always propagation to "somewhere."  Of course, you'd need a General for that, but heck, that's only a written exam and you're finished.  You get credit for passing the code test by virtue of your Novice.  Might want to consider this, if possible, and opt for a more active ham band to use, like 40m.

Sounds like an amazing journey, and good luck!

WB2WIK/6



 
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KB2GBV
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« Reply #2 on: March 02, 2006, 04:53:37 PM »

*Shoot.*

I told you it's been awhile! I got stale...I completely neglected to take the sunspot cycle into account. All I remember is working Japan on my TS-120 w/ a dipole on a *really* good day.  No point in lugging the weight of the radio + tuner if I can't make the contacts.

I'll do some poking around about upgrading to General, but I doubt I can get my act together in less than two months...
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KB2GBV
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« Reply #3 on: March 02, 2006, 04:58:17 PM »

By the way - I've been out of the loop so long, I don't even have a good grasp of the current licensing scheme.

Are you saying I can test for General from Novice *without* a code test? And what about Technician?

(I feel a bit like Rip van Winkle.)
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K0BG
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« Reply #4 on: March 02, 2006, 05:41:29 PM »

While I agree with Steve, there is a minor point or two that needs further discussion. A bicycle frame may indeed be a good groundplane for some frequencies, it isn't very good on any HF band, including the near VHF 10 meter one. Even if you use a full 1/4 wave whip, the other part of the antenna is the bicycle, and it isn't enough. Especially (as Steve eludes to) when the solar cycle is in neap tide, so to speak.

If it were me doing this (I wouldn't on a bet even if I was 25 years old again), I'd stick to 2 meters. If I just "HAD" to have lond-distance SSB, then 6 meters might be a better choice even though the band is all but dead.

Your major consideration will not be the radio, antenna, or frequency of operation, but DC power. That, my friend, is a whole new aspect.

Alan, KØBG
www.k0bg.com
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KB2GBV
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« Reply #5 on: March 02, 2006, 05:58:33 PM »

"Your major consideration will not be the radio, antenna, or frequency of operation, but DC power. That, my friend, is a whole new aspect."

That, I've got. 64 watts of direct solar with a 13.8V DC-DC converter and an 8AH Cyclon SLA deep-cycle battery pack with a near-bulletproof epoxy-emebedded BZ charge controller.

But it looks like I'll mainly be using it to power my laptop, my 3W cellular amplifier, and the CB...with everything I've got to do between now and departaure day (May 1), I don't think I can squeeze in a dual license upgrade!
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K0BG
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« Reply #6 on: March 02, 2006, 06:52:51 PM »

I'm curious, Ian, have you read the QST articles about bicycle mobile? I don't remember when they ran (there were two or three as I recall). I suspect they would be interesting reading in view of your pending adventure.

About 10 years ago, I met a bunch of guys at a rest stop in Western Kansas while on a trip back to Denver, where I used to live. Two or three were hams, and were using 2 meter HTs to keep in touch. One of the non-hams was using a laptop with a build in cellphone for internet access. He didn't use a solar cell, instead he was using an axle mounted generator. Now there's an idea!

Alan, KØBG
www.k0bg.com
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K5LXP
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« Reply #7 on: March 02, 2006, 06:55:27 PM »

Alan-

6M?  Who's he going to talk to on 6?  I have a heck
of a time raising anyone on 2M during cross country
trips, much less 6.

I'm with WIK, while mobile I can work somewhere on
40 just about any time of the day or night.  Yeah,
the efficiency of a bike and a loaded whip on 40
would be very low, but the odds of actually finding
someone to talk to is a whole lot higher.

Good thing you won't be trying this anytime soon,
you'd be talking to yourself a lot!  :-)

To be honest, I don't think he's going to be talking
a whole lot anyway, he'll be too busy pedaling and
huffing and puffing.  When he's stopped he'll be
too tired to talk.  Maybe an HT for 'emergencies'
but I wouldn't worry about having it available while
in motion.  Same with the CB, that gets annoying
after just a few minutes.  I'd have me an MP3
player and a bunch of tunes to maintain motivation.

Mark K5LXP
Albuquerque, NM
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K0BG
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« Reply #8 on: March 03, 2006, 04:38:02 AM »

You're right Mark. I can't see you (or me) doing this, but if we did, remember... now you can download songs and videos directly to your cellphone.

Have you stopped to think....

In about 10 years, after half of the young folks in the country have gone places you and I never dreamed of, all the while with earbuds stuck in their auditory canals, just how lucrative being an ENT will become? If you have any kids in med school, this is the specialization they need to strive for.

Alan, KØBG
www.k0bg.com
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W3LK
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Posts: 5644




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« Reply #9 on: March 03, 2006, 07:36:26 AM »

Ian,

<< Are you saying I can test for General from Novice *without* a code test? And what about Technician >>

Your Novice license gives you credit for the CW exam (Element 1) but you will have to take the Technician (Element 2) and General (Element 3) exams to upgrade to General.

Neither exam is particularly difficult and you should be able to do it in two months if you give it an hour a day.

There are several on line exam sites where you can take practice exams. One of the best is right here on eHam. Look on the left side of the page under RESOURCES and click on Ham Exams.

Good luck with both the upgrade and the trip.

73,

Lon W3LK
Baltimore, Maryland

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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
KB2GBV
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Posts: 5




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« Reply #10 on: March 03, 2006, 04:42:07 PM »

Thanks for the info and advice - I've been checking into the resources here.  It's not so much the difficulty of the tests - I know almost half the questions and half-remember the answers to the other half - it's just that between now and May 1 I have to 1) sell the house 2) put my worldly posessions in storage and 3) train up a bit so I don't blow my knees up crossing the Rockies.

I wish I had thought of this six months ago!

However, even if I don't upgrade before this trip, you can bet I will once I'm no longer a three-wheeled vagabond.
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WB6BYU
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Posts: 13166




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« Reply #11 on: March 10, 2006, 03:43:23 PM »

For the mobile whip, I've mounted a 9' CB whip on my
bicycle before - that would be much better than a telescoping
whip (which are VERY fragile.  But for long distance
riding, I'd probably do without the added wind drag and
use a base-loaded mobile whip instead.  (If you tune it
up for the ham band, you can then attach an alligator clip
to the top of the whip to move the resonant frequency down
to CB.)

What I ended up doing on long trips was to use the ham
rig at night in camp rather than mobile on the road.

40 and 80m are great for this, and I ended up meeting
hams who invited me to stop by when I was passing through
their area.  (Although this would be more likely on SSB
rather than in the Novice bands.)

CW mobile does have the advantage that you don't hear
all that "engine noise" (panting and puffing) through
the mic.
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W3DBB
Member

Posts: 78




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« Reply #12 on: March 17, 2006, 08:51:26 AM »

I'd try something like I use for my 10 meter mobile set-up.

I use a RoadPro Titan II RPSY 385 10 meter multi-mode transceiver (lower-powered version of the RadioShack HTX-100) coupled directly through RG-58 to one of those RadioShack 8.5 foot whips. I mounted the whip to the tongue of my trailer hitch using one of those aluminum 'Iron Horse' IHTH adaptors and a heavy-duty stainless-steel spring.

No tuner or counterpoise was required. After installation I checked the standing wave ratio, then permanantly removed the meter from the line. No pruning of the whip was required.

The transceiver delivers full power to the tall whip with a minimum of insertion loss.
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AD5OS
Member

Posts: 23




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« Reply #13 on: May 16, 2006, 03:53:30 PM »

Just out of curiousity... what is preventing him from getting an RF burn if he is using the bike as his counterpoise... let alone maybe brushing up against the antenna. And what about SAR? check out what this site says about it!

http://www.fcc.gov/cgb/consumerfacts/rfmobileantenna.html

Brian
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