Test Your Tech Skills - Be a HAM

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Bob Scott
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Test Your Tech Skills - Be a HAM

Post by Bob Scott » Sun Aug 30, 2009 1:32 am

Test your tech skills. Online Amateur Radio practice exams:

US or Canadian:
http://www.hamtestonline.com/

US:
http://www.qrz.com/p/testing.pl

Even if you don't want to become a HAM, you can impress your friends and neighbors with your Amateur license. They are inexpensive.

US has 3 varieties: Technician, General or Extra.
Canada has 2 types: Basic and Advanced.

Even if you don't want the license, the exams are good challenging amusement!

Bob
-=VA7KOR=- My solar system includes Pluto.

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Re: Test Your Tech Skills - Be a HAM

Post by Dean Huster » Thu Sep 03, 2009 4:31 pm

I was WN0ZFN for a couple of years. Uncle Sam asked me to join his efforts in the military during the first year and because of all the travel, I never progressed and let the license lapse. It's a shame for I love HF SSB and CW ... never had a use for 2M and up. Trouble is, it's to the point that ham radio has gone the way of everything else -- all computers and turn-key radios. I know it's not really, but if you look at the most current ARRL Handbook, the only thing hams build anymore is birdhouses.

Ergo, my interest has waned. I'd have kept up had I gone on in 1971 (good grief, every military base has a dream ham station using fairly new military equipment) but getting back in at this point just isn't attractive. That's a shame. On me? On the hobby in general? Ah, well.

But don't let me rain on the parade. Amateur radio is still a great segment of the hobby.
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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jwax
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Re: Test Your Tech Skills - Be a HAM

Post by jwax » Fri Sep 04, 2009 2:27 am

WN0ZFN de WA2RBA-
I know the feeling Dean. Built my Eico 90 watt CW transmitter at 12, learned something about resonance while tuning out the orange glow of the 6146 plates, found the gain of an inverted-V over a dipole, and talked with many friendly strangers over the years! SSB was new, the coolest mode to go on (Donald Duck mode), and had to build another kit, which was great!
Remember your first QSL? Best DX? Mine was Poland from Buffalo, NY.
Did your high school have a ham radio club? Wonder if they still exist?
73's to you and all the other old hams that made a fantastic hobby!

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Re: Test Your Tech Skills - Be a HAM

Post by Dave Dixon » Fri Sep 04, 2009 7:55 am

I've been inactive for ages. The only thing I do anymore is listen to the stormspotters when we get our usual Kansas weather. My last great time was using 2 Meter packet to get a reply from the MIR spacestation on one occasion and NASA's space shuttle twice. Hey, it was an automated reply, but exciting to show off that line of sight and 5 watts can get you far! Maybe I'll dig some stuff out of my shed over the extended weekend!!!! 73's de N0QOF
(November Zero Quit Overheating the Finals)

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Re: Test Your Tech Skills - Be a HAM

Post by Dean Huster » Sat Sep 05, 2009 4:30 am

WA2RBA de WN0ZFN:

Jack Cox, K5TQM, lastly of Gulfport MS, now a silent key for many years, was my inpiration. He had a Heathkit 20m xcvr he carried around with him.

I used a Knight-Kit R100A and T150A (throttled back to 75w, of course -- I had a red mark on the meter's plate current scale). I already had the receiver, the fifth Knight-Kit I'd built (and loved every second of it) and bought the transmitter from a guy while in college. I still have both, the R100A still works and is turned on every so often; I have a feeling that if I turned the T150A on, the electrolytics would wipe out the entire inside of the cabinet.
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Bob Scott
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Re: Test Your Tech Skills - Be a HAM

Post by Bob Scott » Sat Sep 05, 2009 7:18 am

Dean Huster wrote:Jack Cox, K5TQM, lastly of Gulfport MS, now a silent key for many years, was my inspiration.
You use facinating diction. You should continue to be an author. If you don't, it's a waste of talent.
Dean Huster wrote:He had a Heathkit 20m xcvr he carried around with him.
I knew a guy who carried a portable CB everywhere he went. His glass was only half full, if you know what I mean.
Dean Huster wrote:I have a feeling that if I turned the T150A on, the electrolytics would wipe out the entire inside of the cabinet.
That's the second time that I've seen you say that electrolytics blow up when they get old. In my experience, they don't leak current. They just lose capacitance so that excessive ripple voltage appears on the DC supply. Keeping them hot, mounted very close to hot power dissipating parts (eg: TV Vertical output Xistor), accelerates the drying of the electrolyte; ages them faster. There is no boom unless wired in reverse polarity or excessive DCV is applied.

When I was a kid my Dad told me this: "It is not good for electrolytic caps to be uncharged for a long time, or used at too low a voltage. If a 600 V electrolytic cap is constantly used at 400V, it becomes a 400V capacitor."

I didn't know they would violently destroy themselves when charged after a long period of discharge.

Bob
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Janitor Tzap
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Re: Test Your Tech Skills - Be a HAM

Post by Janitor Tzap » Sat Sep 05, 2009 6:21 pm

Bob Scott wrote:
Dean Huster wrote:Jack Cox, K5TQM, lastly of Gulfport MS, now a silent key for many years, was my inspiration.
You use facinating diction. You should continue to be an author. If you don't, it's a waste of talent.
Dean Huster wrote:He had a Heathkit 20m xcvr he carried around with him.
I knew a guy who carried a portable CB everywhere he went. His glass was only half full, if you know what I mean.
Dean Huster wrote:I have a feeling that if I turned the T150A on, the electrolytics would wipe out the entire inside of the cabinet.
That's the second time that I've seen you say that electrolytics blow up when they get old. In my experience, they don't leak current. They just lose capacitance so that excessive ripple voltage appears on the DC supply. Keeping them hot, mounted very close to hot power dissipating parts (eg: TV Vertical output Xistor), accelerates the drying of the electrolyte; ages them faster. There is no boom unless wired in reverse polarity or excessive DCV is applied.

When I was a kid my Dad told me this: "It is not good for electrolytic caps to be uncharged for a long time, or used at too low a voltage. If a 600 V electrolytic cap is constantly used at 400V, it becomes a 400V capacitor."

I didn't know they would violently destroy themselves when charged after a long period of discharge.

Bob
Hey, I got caught up in the CB craze too, during the mid 70's to early 80's.
A friend got a vehicle mountable radio, and set it up with a 12V Nicad battery pack.
And adapted a scanner antenna for it.
It worked ok, thou, he could only get about 3 hours out of the batteries.
He could of gotten one of the hand held radios that Radio Shack sold.
But at the time, it was cheaper to build up his own portable CB setup.
{That and the vehicle units had more transmitting power.} :lol:

Well, as for old electrolytic capacitors.....
It is true that they can sometimes explode.
I should know, I've had enough of them pop on me. :lol:
On older equipment, as you say, tends to be do to heat drying them out.
But I have come across bunches of defective electrolytic capacitors.
{Especially ones that came from China.} :lol:
These were in SMPS in VCR's: GE, RCA, and a few other brands that used the same design of SMPS.

As for caps sitting on shelves for long periods of time.
Yeah, It isn't a good idea to place the electrolytic into a circuit without checking it first.
There is a method for reforming old electrolytic's.
But I've never tried it.
I've always replaced the defective electrolytic with a new one.

But I was always told that whenever powering up a old piece of equipment.
Put it on a variable isolated AC supply, and slowly bring the AC voltage up.
Watching the Amp meter in case the current starts to climb to high, indicating a shorted cap.
Thus, shutting it down before you do damage to it.

I had a little GE portable TV that came in for a electrolytic problem.
It was strange, The set had popped the 1.5A Fuse.
I replaced the fuse and slowly bought the power up to 110VAC.
It worked fine.
I shut off the set, and turned it on several times.
It seemed fine.
I then unplugged it, and put the back on the set.
I then plugged it back into the 110VAC.
I turned it on, I heard a faint pop, and the set was dead.
Opened it back up, here the fuse had popped again.
This time I grabbed a 1A circuit breaker and jumper it onto the fuse.
I slowly bought the power up to 110VAC.
The set came on and was working.
I unplug it from the AC Variac, going directly to the 110VAC again.
The set ran fine.
I then unplugged the set, and left it off for 5-10 minutes.
I then plugged it back in and tried it.
The circuit breaker popped right away.
Well, here's where things got interesting.
At the front end of the power supply.
Just after the full wave rectifier diodes, sits a 680uF 200Vdc electrolytic filter capacitor.
I did simple tests for leakage, with a hand held meter, but it showed it to be fine.
Well at the shop I had excess to a Z-Meter.
Boy do I wish I could of bought it when the shop closed.
The Z-meter shown that the electrolytic had very slight current leakage,
just enough to cause the cap to act the way it did.
I replaced that electrolytic, and then the set fine.

Now when I see a popped fuse on a set.
I now always check the electrolytic filter capacitor right away. :wink:


Signed: Janitor Tzap

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Bob Scott
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Re: Test Your Tech Skills - Be a HAM

Post by Bob Scott » Mon Sep 21, 2009 11:05 am

Well, for the last couple of weeks I was learning the legal and physical laws about amateur radio. I did a heck of a lot of learning from being wrong at mock test answers. Last night I met a volunteer examiner and took both the Basic and Advanced license exams with, uh, results of 98% and 96%, so I guess the guvm'nt will be sending me a license to transmit all over every amateur frequency. That is, if I ever get any ham equipment and have the will to install a multi-band antenna antenna in the back yard. Then I can "jawbone" :???: . I guess being a ham really does not have the exitement it used to in the olden days. Anyone can pick up a cellphone and call anyone they want to talk to in the world. Who needs a radio? A funny thing is, according to the regulations of Canada, if I talk to a foreign amateur my conversation must be "limited to technical chatter and personal subjects of no consequence". US amateurs have no such limitation to their freedom of speech, and neither do phone calls to anywhere!

Maybe the hobby is more of a social activity for amateur clubs. Me, I finally get to experiment with designing and building equipment to make any kind of modulation that I can invent.

Did I mention everything so far has been free of charge? Even the lifetime license that is still in the mail. It won't ever expire.

Bob
Tentatively,
VA7KOR
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Re: Test Your Tech Skills - Be a HAM

Post by jwax » Mon Sep 21, 2009 1:22 pm

au contraire mon ami! Ham radio is and always will be an exciting hobby because anybody can pick up a phone and dial anywhere, but to spend countless hours soldering, drilling, wiring, building, and tuning their own transmitter, not to mention tackling the life-threatening feat of antenna construction, well, sir, that makes a difference when you say "73's" to a stranger on the airwaves! Despite what the doomsayers say, you can't get an RF burn from a cellphone, but touch that transmitters tuning cap with a few hundred watts of 21 MHz, and you'll thank the gods you had the privilege of building your own! :smile:
Congratulations, by the way!

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Re: Test Your Tech Skills - Be a HAM

Post by haklesup » Mon Sep 21, 2009 4:46 pm

I guess being a ham really does not have the exitement it used to in the olden days. Anyone can pick up a cellphone and call anyone they want to talk to in the world. Who needs a radio?
While its true that the Internet provides a means for just about anyone to chatter to a stranger on the other side of the word (I do it here in this very forum) it (HAM) still has an essential role in disaster management. In a natural or terrorist disaster, cellular and internet networks may be partially inaccessable in the areas where they are needed. A HAM only really needs some electricity and the ability to fix his own antenna (should it be damaged by said disaster). True some uses are obsolete, but others are not. IN between disasters, chatter becomes practice. The license is also a great credential in one would ever want to get into a commercial broadcast job (engineer not a broadcast personality)

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Bob Scott
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Re: Test Your Tech Skills - Be a HAM

Post by Bob Scott » Tue Sep 22, 2009 7:32 am

jwax wrote: ..............but touch that transmitters tuning cap with a few hundred watts of 21 MHz, and you'll thank the gods you had the privilege of building your own! :smile:
Congratulations, by the way!
Thanks John. By the way, you have one wry sense of humour. hehe, "thank the Gods",,hehe :lol:

Hackles: I guess I did it backwards. I had the broadcast "engineering" job beforehand, but during that time never set my eyes inside a transmitter. There were a couple of techs whose sole job was to maintain the (out of the city) transmitter. This is long after.

Bob
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Re: Test Your Tech Skills - Be a HAM

Post by Dean Huster » Thu Sep 24, 2009 6:14 pm

"Exploding" electrolytics have a lot to do with how much power the raw supply is capable of delivering. "Exploding" is usually more in the form of venting, but true "exploding" ruptures are not uncommon.

I made a safety video for students showing them the problem of installing reversed-polarity electrolytics on their breadboards. It took more time that I'd expected from a 1a supply. But when they exploded, it impressed the cameraman. You couldn't find much of the innards of the things when it was over. The axial-leaded versions weren't so bad because both halves remained attached to the breadboard. The radial-leaded caps were more dangerous as the can shot off like a bullet and could easily put out an eye. In both cases, the aluminum case was split like a can of Coke in the freezer.
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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Re: Test Your Tech Skills - Be a HAM

Post by Robert Reed » Thu Sep 24, 2009 8:01 pm

I have reversed polarity of aluminum 'lytics on several occasions, but the worse thing that happenened to me was the case bulging from exessive heat. Maybe I turned the power off soon enough to prevent further catastropy. At any rate, it didn't leave much of an impression on me.
However, the first time I reversed poilarity on a tantalum 'lytic it literally exploded like shrapnel spewing particles everywhere and with a LOUD bang. Some of the particles were hot enough to imbed into the lenses of my plastic eyeglass lenses. It literally left me shaking as I could have been blinded if not for my glasses. Now I was impressed and have never forgotten that session. So be it tantalum or aluminum, I am always double checking polarity marks when installing them in a circuit.

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