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Author Topic: So, what happens AFTER we get the license?  (Read 13675 times)

WA4STO

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Re: So, what happens AFTER we get the license?
« Reply #15 on: September 30, 2012, 03:17:53 PM »
...and, um...looking at my dipole antenna mast...and I can't seem to find any coils to tweak?  ;)

...actually - I think I get the fact that I'm supposed to use those connector pieces to add a bit more wire onto the existing leg - and remove it to bounce between 75/80...

...which means that 80m is definitely going into an inverted V!


What?  No coils?  Surely you did something wrong in the whole process.  Hmmm...

Yah, I thought about your 100 feet between the trees situation; adding to the already-long 80 meter elements is definitely going to pose a problem.

If it t'were me, I'd leave it alone for now, banking on the assumption that they cut it for 75 meters.

No, the insertion of the PowerPole connectors won't cause the SWR to change.  However, the added length of wire to each end most definitely WILL, of course.  At least on the 75 meter part; it should go sky-hi (no pun intended) if you add several more feet (more on that in a bit).  But that's the goal of adding wire; to get the whole thing to resonate lower down in the band, which clearly DOES require more.

How much?  Lessee:

Wild-ass-guess here but let's say that the theoretical length of a dipole resonant at 3.947 mHz is:

492 / 3.747 = 124.7 feet (62 feet on each side of the insulator)

Now if we want it to resonate on, say, 3.620, we would get:

492 / 3.620 = 135.9

which would be 6.5 feet added on each side.  That's instructive!

73 de WA4STO

gil

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Re: So, what happens AFTER we get the license?
« Reply #16 on: September 30, 2012, 03:22:45 PM »
Tim, that's the vertical antenna itself here that has the coils, not the mast. You shouldn't have any coils for a dipole, except if it was shortened, and then the coils would be on the radiating wires...

Gil.

White Tiger

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Re: So, what happens AFTER we get the license?
« Reply #17 on: September 30, 2012, 05:26:12 PM »
You guys are killing me here...

Between STO & Gil - there's definitely a "rainman" effect on the antenna issue...

"...yeah, yeah...definitely need coils on radiating wires cut 139.5' to resonate on 3.620"

This is why I'm skeptical I can pass the Amateur Extra class exam....that is just for uber smart (Rainman-like) amateurs!!

Can you just give me a Mnemonic download (and you're going to have to be careful not to overload my limited storage capability)?

If you're looking for me, you're probably looking in the wrong place.

WA4STO

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Re: So, what happens AFTER we get the license?
« Reply #18 on: September 30, 2012, 05:34:01 PM »
OK, here's a "binary" way.  One that I've suggested 4237 times before.  More or less.  Here goes:

Memorize the answer = ON

Memorize the answer = ON

Memorize ... oh ... you get the drift.

Here's the way I view your exam studying status:

1.  Technician = Done!

2.  General = Done!

3.  Extra = durned near done!

If you wait to take all three until you understand everything on the exams, you better be looking at a test date in 2015.

Not that YOU couldn't learn it; it's just that to get there from here, you gotta stop worrying about what puzzles you, cuz the exam session is like NOW!   Well, real soon now...

73 de WA4STO

gil

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Re: So, what happens AFTER we get the license?
« Reply #19 on: September 30, 2012, 05:37:48 PM »
Well, it's simple really... If you want to shorten an antenna, you place a coil somewhere on the wire(s). Of course there is a bit of math involved there, as to where to place the coil, how many turns, what diameter, what type of core, and wire diameter.. Stuff I don't ever want to get into.. I usually browse the web until I find someone who has done the work for me and published it! Note that coils mean losses.. The bigger the wire diameter the better in that regard..

Tim, read the book I traded that hot chocolate for with you and just give it a shot, you never know.. I didn't think I would pass all three exams, honestly. Do a lot of practice exams on QRZ.com, that will help you memorize the most difficult answers. A lot of the stuff is common sense. The cool thing is, you also learn a lot of stuff and you'll be ahead for the next session.

Gil.

White Tiger

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Re: So, what happens AFTER we get the license?
« Reply #20 on: September 30, 2012, 06:03:18 PM »
Here's the way I view your exam studying status:

1.  Technician = Done!

2.  General = Done!

You're dead on...I'm scoring 85% to 91% based on an algorithym that pulls test samples from several aspects of the question pool (i.e., "weak areas", "unseen items" and "truly random")...so, yeah...I'm pretty confident, unless I get Mad Cow disease between now and next Saturday, these should not be a problem for me.

Actually, HamTestOnline has me feeling like a rockstar...

3.  Extra = durned near done!

...until I get to this^^^ portion - where I am still consistently scoring 40% to 50%...which as you know is well below "failure"!

Dunno - maybe it's the fact that there are 15 more questions - which decrease the odds of getting a question I've already memorized, substantially (and actually feels like "exponentially)...maybe it's the fact that some of the questions are simply rephrasings of the question pool from the General...or or I'm brain dead!?

If you wait to take all three until you understand everything on the exams, you better be looking at a test date in 2015.

..that's true - and you never know about the gubmn't - they could change their criteria at any time...this is what is driving me to take the test, well that and Gil's admonishment that once you walk away from the test, you can become comfortable without ever upgrading your license to the next level...

Not that YOU couldn't learn it; it's just that to get there from here, you gotta stop worrying about what puzzles you, cuz the exam session is like NOW!   Well, real soon now...

I know - my jonesin' on this subject (worrying about passing) is probably driving everyone crazy! ...but you're right - it's so close, there's only time to read & take tests!!
« Last Edit: October 02, 2012, 10:37:59 PM by White Tiger »
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gil

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Re: So, what happens AFTER we get the license?
« Reply #21 on: September 30, 2012, 06:30:52 PM »
The last few nights, I was going to sleep at 2-3am after hours of reading.. When I got to the exam session, it felt like I had forgotten most of it! The first two went well, but the last one, I thought I had failed. The thing is, I think that my reading helped me make a lot of educated guesses... The first key is to read the questions entirely, slowly and precisely. The second key is to not care about the results (gee, I sound like I'm teaching martial arts students) ;D If you don't get Extra, no big deal. Just make sure you DO go to the next session!

Gil.

Jonas Parker

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Re: So, what happens AFTER we get the license?
« Reply #22 on: October 01, 2012, 11:43:29 AM »
I've been out of college for some 50 years."Extra" was a bear for me since it was a long time ago when I took college algebra and physics. I used the interactive course at www.hamtestonline.com and managed to pass the exam on the first try after about 3 months of studying. I hope this helps.

White Tiger

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So, what happens AFTER we get the license?
« Reply #23 on: October 01, 2012, 10:50:50 PM »
That is the test site I am using - I'll post a review of how well I feelHamTestOnline prepared me on Sunday...as my exam is on Saturday.

So far it seems like an excellent preparatory tool for the exams!
« Last Edit: October 02, 2012, 10:42:58 PM by White Tiger »
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AE5J

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Re: So, what happens AFTER we get the license?
« Reply #24 on: October 10, 2012, 12:48:03 PM »
Being an inveterate tinkerer who has put huge eyesore antenna-like contraptions in the air for a long time, let me direct you to a couple of antennas that really make the idea of remote (that is away from large pre-erected antennas) operations a lot easier. I use these when out in the RV.

The first is the Buddipole. I have a large assortment of their stuff and in short, it works. Surprising well. It also is so flexible you can learn a vast amount about antennas by playing with it. Here is a link:
http://www.buddipole.com/
This stuff is not cheap, but it is of amazing quality and performance for field work. there are some great videos of the Buddipole on youtube as well.

I have built fan dipoles for many years, but lately I discovered the end-fed antenna. Here is one of the best pre-built ones:
http://www.ebay.com/itm/QSO-KING-End-Fed-Antenna-All-HF-Bands-1-9-KW-PEP-HOA-Friendly-Works-A-/170836265100?pt=US_Radio_Comm_Antennas&hash=item27c6a2888c
This one is inexpensive, highly portable, and much easier to erect than a dipole, as it only requires one elevated support and it is fed from the end close to the ground.

You can read reviews on e-ham.net if you like such things.
73....Pete

Sunflower

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Re: So, what happens AFTER we get the license?
« Reply #25 on: October 10, 2012, 01:57:30 PM »
Remember that NVIS is a technique, not a hardware solution. You're just utilizing a different take-off angle and gives you that near-range plume like a rising bran muffin.

Not sure I understand the bran muffin part. What is NVIS (navigating an antenna?).

Mitch

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Re: So, what happens AFTER we get the license?
« Reply #26 on: October 10, 2012, 02:27:13 PM »
NVIS stands for near vertical incidence skywave.

That's a mouthful for sure, but explaining it may be worse.

Keep in mind that radio operators like to use the ionosphere to bounce signals off of to get greater range that's the "propagation" effect you keep hearing about.

When someone transmits a signal from an antenna typically they want to send (point) it toward the horizon so it skips better (at a lower angle- like skipping a rock on the pond) to go further.

If they want to use NVIS they set up the antenna and choose a frequency that will still bounce off the sky even if they shot it straight up. Like dropping a rock straight down on the pond and having it bounce back to your hand!

They then shoot that signal almost straight up, but when it comes back down the receiving area on the earth is much smaller because of that small angle it bounced.

If done properly the benefits are:
1. Antennas are somewhat easier to set up since they don't have to be high off the ground.
2. The received signals tends to be clearer because an NVIS antenna doesn't pick up as much regular noise since it is low to the ground (doesn't hear regular signals as well)).
3. It's much more forgiving for using lower power 100mW is sufficient in most cases.

Primary negative points are:
1. It's only for shorter range. (Since the signal rock is only skipping the pond once.)
2. You only get to play with other stations with an NVIS antenna. Regular antennas can still "hear" you but you may not hear them because your antenna isn't high enough to efficiently catch their signal.
3. If you chose the frequency too high it escapes into space and doesn't come back down!



P.S. I probably didn't answer the question. The "bran muffin" part... I haven't got a clue! ???
Sorry for explaining NVIS again in this thread.
« Last Edit: October 10, 2012, 02:44:56 PM by Mitch »

White Tiger

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So, what happens AFTER we get the license?
« Reply #27 on: October 10, 2012, 03:38:37 PM »
No worries, and yes I know that NVIS is more of a technique utilizing a dipole - but it does require a different antenna configuration of the dipole...so rather than taking the antenna down and reconfiguring it to be less than a 1/4 wave (or a little over 7'-8' whichever comes first) from the ground - I'd prefer just setting up two dipoles...

...I think...
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Sunflower

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Re: 80 vs 75, SSTV in the voice portions of the band
« Reply #28 on: October 13, 2012, 06:20:38 PM »




73 de WA4STO

Why coils? to keep the connection cooler? First time I ever saw coils. Do the coils shorten up would be too lenthy to handle otherwise? Are the coil SS or alunimum? Are the pads that connect between the two a form of insulation? Do the coils speed up your CW or just voice?

Did you make this yourself?

Thank you

WA4STO

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Re: 80 vs 75, SSTV in the voice portions of the band
« Reply #29 on: October 13, 2012, 07:50:39 PM »

Why coils? to keep the connection cooler? First time I ever saw coils. Do the coils shorten up would be too lenthy to handle otherwise? Are the coil SS or alunimum? Are the pads that connect between the two a form of insulation? Do the coils speed up your CW or just voice?

Did you make this yourself?

Thank you

Last things first:  No, I didn't fabricate/make all these parts.  None of them, actually.  However, I did assemble it.  Since I'm such a mechanical DUNCE, it took me about four good days, or at least those (small) portions of a day when I'm feeling up to it, lol

An antenna needs to be a certain length to be resonant at the frequency you wish to operate.  And, as you've learned here and elsewhere, a resonant dipole antenna for the 80 meter amateur radio band is something on the order of 125 feet long!

This design of this antenna is a compromise.  I can't have an antenna that's 125 feet tall, cuz if it fell over in a storm, it would end up killing somebody (guess who, probably?) when it fell on the power lines.  So, to make the antenna shorter, you have to design into it some electrical properties such as inductance and capacitance.  In general, those big coils provide the inductance, while the little brown "pads" that you saw are actually capacitors.  Together, if designed correctly, the overall antenna APPEARS to be "longer" (in this case MUCH longer!) than it actually is, so that radio will be happy and will allow the flow of electrons out into the wild blue yonder without frying your radio. 

It may be that you've seen "coils" before and didn't realize it.  Here's a picture of a bunch of them, designed into an HF Yagi antenna:



There's a bunch of coils on that particular antenna.  You can't tell by this picture, but the coils are closed, encapsulated inside some material or another so that rain, moisture and bird doo-doo (just kidding, kinda) don't get into the coils.  Problem is, they do eventually leak, or rather, the moisture gets IN to them and they are expensive to replace.

The ones on my antenna are totally open so that moisture can have it's way (not) from day one. 

One other VERY nice feature of the open coil design is that you can adjust the frequency that the radio will best be able to squirt out those electrons.  When I first put mine together, I needed to go outside and gently pull the coil windings apart a little.  Worked great and that's part of why I love this antenna.  Love the price?  Not so much.

Here's another design that you have likely seen and not paid much attention to until now.  It's a CB antenna, the type of which is often found on the trunk of CBers' automobiles.  The big black thing?  You guessed it, a coil!



Neither coils nor capacitors relate to CW, voice (or digital modes, for that matter) speed in any meaningful way.  Once the antenna has become resonant at the frequency that you want to operate on, then -- no matter what mode you use --   you can transmit (and receive of course) much much better/further/stronger than when it wasn't tuned properly.

To answer your question about aluminum vs. stainless steel, I forget, but am quite certain that it surely must be aluminum.  Stainless would add SO much weight (a bad thing) and would be hard to stretch/compress to tune it.  Yah, must be al-loo-min-e-yum.

Hope this answers your questions.

73 de WA4STO
QTH: Wilber Nebraska