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Radio and Electronics Humor


Murphy's Engineering Laws

Source: This came from an e-mail a friend forwarded to me...


The Gold Plated Antenna

Well its been some years back ...BUT ... I once had a gold plated antenna.

Man.... that thing looked really sharp shinning in the sunlight but It was a real pain in the neck because the gold molecules would tend to migrate toward the ends every time I transmitted. Kinda like the electroplating process moves the gold molecules from one place to another. Anyway, It didn't take long for the length to change enough that I had to climb up there and trim a bit off to keep it in tune. I understand that silver plated antennas do not seem have this problem. After about three years of rag chewing I took all the gold I had sniped off at the ends and sold it to a jeweler down the street for enough money to buy a regular aluminum antenna. I guess someone, somewhere is walking around wearing what is left of my old antenna. Climbing up to trim that dern old gold plated antenna is the reason I have all those palladium pins in my backbone, but that is a whole nother story.

a posting by William Lee, N5WRX


Accidents Will Happen

I am writing in response to your request for additional information for block number 3 of the accident reporting form. I put "presence of mind" as the cause of my accident. You said in your letter that I should explain more fully and I trust the following detail will be sufficient.

I am an amateur radio operator and on the day of the accident, I was working alone on the top section of my new 80 foot tower trimming the ends of my gold antenna. When I had completed my work, I discovered that I had, over the course of several trips up the tower, brought up about 300 pounds of tools and spare hardware. Rather than carry the now un-needed tools and material down by hand, I decided to lower the items down in a small barrel by using a pulley, which was fortunately attached to the gin pole at the top of the tower.

Securing the rope at ground level, I went to the top of the tower and loaded the tools and material into the barrel. Then I went back to the ground and untied the rope, holding it tightly to ensure a slow descent of the 300 pounds of tools.

You will note in block number 11 of the accident reporting form that I weigh only 155 pounds. Due to my surprise of being jerked off the ground so suddenly, I lost my presence of mind and forgot to let go of the rope.

Needless to say, I proceeded at a rather rapid rate of speed up the side of the tower. In the vicinity of the 40 foot level, I met the barrel coming down. This explains my fractured skull and broken collarbone. Slowed only slightly, I continued my rapid ascent, not stopping until the fingers of my right hand were two knuckles deep into the pulley.

Fortunately, by this time, I had regained my presence of mind and was able to hold onto the rope in spite of my pain. At approximately the same time, however, the barrel of tools hit the ground and the bottom fell out of the barrel. Devoid of the weight of the tools, the barrel now weighed approximately 20 pounds.

I refer you again to my weight in block number 11. As you might imagine, I began a rapid descent down the side of the tower. In the vicinity of the 40 foot level, I met the barrel coming up. This accounts for the two fractured ankles, and the lacerations of my legs and lower body. The encounter with the barrel slowed me enough to lessen my injuries when I fell onto the pile of tools, and fortunately, only six vertebrae and three ribs were cracked.

I am sorry to report, however, that as I lay there on the ground in pain, unable to get up, and watching the empty barrel 80 feet above me I again lost my presence of mind. I let go of the rope...

from a posting by William Lee N5WRX, based on "Accidents Will Happen" by Gerald Hoffnung




To invent, you need a good imagination and a pile of junk. - Thomas Edison


My designated driver is a 12BY7A...


On my first job out of college, I attended a class dealing with writing contracts and specification for work we had done by contractors. Right after I got back from the training, one of the old timers showed me a set of specifications he had written to have some equipment refurbished.

Part of this specification said, "Remove and replace arc chutes." Eager to show my new knowledge, I mentioned an example in the class where they had said you should say, "Remove and replace with new." Otherwise, a cheap contractor might just put the old equipment back in. For example, you remove your coat from a hanger and you later replace it on the hanger.

Of course he gave a knowing chuckle and told me that when I had a few years of "real world experience" under my belt I wouldn't worry about these types of things. He'd been doing this for thirty years and knew how things were done. Besides, his contractor respected him--they knew better than to play games like that.

The contract was let to the low bidder. They came in, removed the arc chutes (the huge guts of four foot tall circuit breakers used in powerplants), wiped them clean, and put them back in. When the old timer told them that they had to put in new arc chutes, they pointed out that the contract didn't say that. By coincidence, they did have a new set of arc chutes that they could install. But since this was beyond the original scope of the contract, they needed a change order and more money before they'd do it.

Quietly (and for some reason, without seeking my advice) the old timer issued a contract modification. I didn't hear about it until a few weeks later when I was at the powerplant. The electricians were joking about how the old timer had let a contractor get the best of him. Of course I couldn't resist sharing that I had warned him based on my "book learning", and telling them my part of the story.


WARNING: Smoke is factory installed and cannot be field replaced.


The wireless telegraph is not difficult to understand. The ordinary telegraph is like a very long cat. You pull the tail in New York, and it meows in Los Angeles. The wireless is the same, only without the cat. -Albert Einstein


Would you believe the best way to test a suspected loose connection is a Wire Integrity Gentle Gyration Looseness Exam (or WIGGLE for short)? No, I wouldn't either...


I'm on a couple of e-mail lists and sometimes just have to shake my head at things.

Once there was a discussion about testing and calibrating an SWR meter. I mentioned that one trick I sometimes use is to put two dummy antennas on a coax T-connector. This puts them in parallel and gives you a 25 ohm load which presents a 2:1 SWR to most radios.

Within minutes a blazing response hit the list. Obviously, it said, I had taken the "give-me" tests instead of the tests they'd given in the old days. Everyone knew SWR was a measure of reactive power, not resistance! A resistor "isn't going to have any SWR!" You measure resistance in ohms, not as SWR. They should never have changed the tests so you could just memorize the answers and let idiots like me get a license!!!

I'll admit I looked through the handbook the first time I went through all of the math on this, but you can take my word for it (or look it up yourself) that you will see a 2:1 SWR for a 50 ohm transmitter operating into a 25 ohm or a 100 ohm load. And SWR measures impedance mismatch--whether it's "reactive" or not.

And, not to brag, but I didn't memorize the exam answers. In fact, I never studied for the Extra exam. I just had enough residual knowledge left from four years of college while earning my degree in electrical engineering to squeak by.


Another group discussion talked about using a battery with a trickle charger to power your transceiver. Not a bad idea and cheaper than a lot of heavy-duty power supplies.

Someone suggested using a filter capacitor--not necessarily a bad idea. And one helpful soul reminded everyone that the filter capacitor needed to be after the battery, not before it. The problem with this suggestion is that from the description of the circuit the capacitor, the battery, and the trickle charger were all hooked in parallel. There really was no "before" or "after" in this situation.

Battery life is often measured in terms of discharge/recharge cycles. Someone else on the list decided that since you'd be "recharging" the battery 60 times a second (line frequency) and allowing it to discharge 60 times a second, your battery life would only last a few hours.

There's a couple of problems here. First, with a full-wave rectifier bridge you'll see a waveform going from zero volts up to full voltage and back down 120 times a second (at least in the US). But even with this connected to a battery, you won't "Discharge" a battery--the diodes in the charger prevent reverse current flow. And even if you did slightly draw current from the battery, this isn't the same as discharging the battery.


And speaking of diodes...

On one list someone wanted to combine two audio signals together and feed them into a single speaker. Someone's helpful advice was to make sure you use diodes--they prevent reverse current flow when you use them with batteries and might just do the same thing with an audio signal.

Well, all righty then...


Some people don't reserve their flashes of brilliance for e-mails.

I once saw a guy operating a demo station and cussing the fact that the club had saddled him with an low-cost antenna tuner. Several times I saw him change bands, hit the key, and flip the switches on the tuner back and forth.

I mentioned that most tuners weren't designed to handle the high voltages you might see if you tuned while operating the transmitter at full power. "I'm not transmitting, I'm tuning up," he responded.

After a few hours, the antenna tuner was toast. The contacts on the switches used to select inductor taps were ruined from arcing. I guess the antenna tuner couldn't tell the difference between 100 watts of tuning up and 100 watts of transmitting.

By the way, it was an MFJ tuner and they replaced it under the no questions asked warranty. Seemed like a pretty stand-up thing to do when a look at the switch contacts would have told them it had suffered some significant abuse.


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