Every year I like to attend/work the K7LED Mike and Key Radio Club flea market. I really enjoy seeing what is being sold and catching up with old friends that I don’t see often. This last year, I bought myself a new soldering tool. I also picked up an older solid state two meter transceiver (yes, I know that this blog is dedicated to tube rigs and other such things, but a tube rig would be a bit big for bicycle operations). Currently the radio doesn’t work. However, the is often the case with used gear that is found at a flea market, and that is part of what makes this hobby so wonderful. It is often great fun to repair/restore an older radio to full function. I heartily encourage that if you can attend a flea market, and particularly an amateur radio flea market, that you do so. We ham really can have fun with these. In fact, we often have more fun than a hog in a bog.
Exoplanets are trending currently. Why? Recently NASA discovered an exoplanet orbiting a star in the Proxima Centauri system. This planet orbits within the “habitable zone”, and is named (by us) as Proxima B. However, because of its rapid rotation around its star, roughly twelve days to complete an orbit, and the fact that while it is withing the “habitable zone”, it is believed to receive 400 times the X-ray energy from its “sun” than we receive from ours. To that end, it is likely that it is comparable to either Mercury or Venus, both of which are barren and devoid of life.
Why do I bring this up? Humanity has been looking for extraterrestrial life for decades. One would think that it is only a matter of time until we find something, right? Maybe not.
2016 marked the 100th anniversary of the W7DK/W7OS Radio Club of Tacoma. This is the single oldest, continuous, ARRL affiliated radio club in the whole of the United States. This is a big deal when you consider that on 23 December 1900, Reginald A. Fessenden became the first person to send an audio single via wireless transmission , and that he made the first commercial broadcast on Christmas Eve of 1906. This means that radio has been a known medium of communications for 116 years, and that there are some earlier experiments that predate these two events.
What does this have to do with aliens? Plenty, if you don’t mind some pretty extreme mathematics. It really has to do with how far radio waves really carry, and they really do carry quite some distance.
I’m going to go ahead and be generous. That is to say that I’m going to ignore the first 16 years of radio transmissions, at least for the moment. Those first sixteen years really are important, but I want to make things easy, at least to start with.
A radio wave travels at the speed of light, which is roughly 186,200 miles per second. This works out to 11,172,000 miles per minute. That, in turn, works out to 670,320,000 miles per hour. In the course of twenty four hours, a radio signal will travel 16,087,680,000 miles. This is nearly four times the distance between the Earth and Pluto. In a month, that signal will have traveled over 482,630,400,000 miles. That means a radio signal will travel, in one year, a distance of 5,876,025,120,000 miles. In a century, that distance is clearly seen as being 500,876,025,120,000 miles. This doesn’t account for those first sixteen years, which adds another 94,016,401,920,000 miles to the overall total.
All that looks impressive, but meaningless, until you start to look at a list of all the potential exoplanets that are thought to exist in the habitable zone. About a quarter of those planets are less than fifty light years from Earth, and some are even closer than that. To date, we have not received an authenticated signal back from any of these supposedly closer exoplanets. Let that sink in for a second.
Over the years, we’ve seen numerous UFO sightings, some going back as far as 1697, though the first fully credited sighting was in 1947 near Mount Rainier, in Washington state. Yet, despite these supposed sightings, we have no hard evidence that extraterrestrials exist, aside from various conspiracy theorist drivel, much of which is easily debunked. Even the “WOW signal” from 1977 has now been attributed to a passing comet, a theory that may very well be tested soon, which only further depletes the potential pool of evidence for extraterrestrial life, and only leaves the flimsiest of evidence, and that being the previously mentioned stuff that is easily debunked.
What does this mean? Ultimately, it means that in all of decades of searching for extraterrestrials, we have found nothing. Furthermore, with at least six exoplanets existing within 56 light years of earth, if they had a level of technological development equal or greater than that of our own (most people seem to seek extraterrestrials with a greater level of technological development for some reason), then we should have already heard something from them, something that would have already put our world into technological overdrive, as we rapidly built a deployed our first hyper-light drive systems. However, no such signal has been shown to exist, and most claimed signals have either been debunked, or have been relegated to suspected pranks by unscrupulous individuals with questionable motives.
Radio has been around for over a century. If there were an extraterrestrial race with a level of technology equal to or greater than our own, we would likely have heard back from them, and it would have been impossible for any government to block such a communication. I know some will believe that I am wrong, and I accept that, but I am firmly convinced that radio, and the lack of an authentic signal from an extraterrestrial race that off of the Earth has heard, is sufficient evidence to suggest we are alone in the universe. This is observational science, and radio is all about what we can observe. If I can be proven wrong, by a personal radio greeting by an extraterrestrial, and they can prove it, I will admit to it, before committing suicide.
Electric lights are everywhere. So much so, we tend to take them for granted. Electric lights have come a long way from the their early start in 1802. Light bulbs, and now Light Emitting Diodes (LED’s) are in almost every appliance on the market, including coffee makers, and radios.
Truthfully, I am unable to determine the first radio to incorporate an electric light within the chassis. I strongly suspect that the inclusion of an electric light was based upon an observation that vacuum tubes (or thermionic valves, as they were once called) have a tendency to glow when power is applied to them. I have read it both ways as to which inspired which, bulb or tube. I really don’t know. What I do know is that at least in 1934, possibly even before then, radios were incorporating electric lights as a part of the overall design.
What purpose does a light bulb serve in a radio? On a purely functional level, they serve no real function. Light bulbs don’t do a thing to make a radio work right. In fact, I have never observed a radio to not work, even if the light bulb is dead. It would seem that the light merely is an aesthetic device, meant to light up the tuning dial or band spread meter, though it is helpful if you must operate in an otherwise dark room, or closet.
So, what happens when a light bulb dies? Truthfully, that is when things get tricky. In our modern age, incandescent bulbs are becoming increasingly difficult to find. If you happen to own a vintage/antique rig, and it requires light bulbs for the tuning dial, you might find yourself at a severe disadvantage, and unable to find a suitable direct replacement. This is a situation that I am certain to find myself in eventually, as I happen to own a 1934 Patterson PR-10 Allwave Receiver.
I admit, some hardware and electronic stores do carry some type of specialty light bulbs, but they are few, far between, and often quite expensive. However, if you are willing to pay the price for it, and it is there, it is most certainly worth it to buy something that is almost guaranteed to work. However, if it doesn’t exist, or your budget is quite tight, you might be up the proverbial creek. Or are you?
At the beginning of this article, I mentioned LED’s. Now I am well aware that these modern devices are not the greatest choice of replacement for the older style screw in incandescent bulbs that our older rigs came with, but they can be made to work. However, a few basics need to be understood about how an LED works.
To start with, the voltage of rating of an LED is about 2.6 VDC, and it must be forward biased. This means that, unlike an incandescent bulb, there is a definite direction of current flow. This also means that you can simply solder in an LED and expect it to just work. The simple truth of the matter is that your antique radio may be providing far more voltage, or amperage, than a typical LED can handle.
That leads to next concern, voltage and amperage. An incandescent light bulb can talk more current than an LED can. Thus, it would be wise to take a volt/ohm meter and test the connectors of where the light bulb goes to determine how much voltage and resistance are present at the point in which the light bulb connects. Some bulbs feed directly off the 117 VAC power supply, and make an LED completely unsuitable for use as a replacement for an incandescent bulb. Even if the voltage is direct current, you still need to discern which point leads to ground and which is live, thus a schematic diagram of the radio in question might prove helpful.
This leads to the next question, if direct current is on the circuit for the bulb, how do we connect an LED? I would hope that you haven’t thrown away that burned out bulb yet, and I would also hope you wrote down everything you can about it, in hopes of finding a proper bulb. That being said, break the bulb.
Yes, break it. You will need to base of the bulb to solder in a resistor to reduce current to the LED and the LED itself. The resistor will have to be soldered inline with the input side of the LED, which should be well marked. The LED output should be soldered to the part of the base that leads to ground. As early model radios varied in terms of bulb voltage from brand to brand, and model to model, I can not give proper specifications regarding how much resistance will be needed to provide enough voltage for the LED without providing too much. Sorry, even I have limitations. After that, you can simply screw the bulb base in and push the resistor off to the side to keep it from obstructing the light from the LED.
I will be honest, this is NOT ideal. However, as is the main principle of Mechanical Ham, it is functional. It does what it needs to, and without getting overly complicated. However, I can not promise that this will work with every radio made. I have encountered quite a few radios, including old general coverage receivers, in which it is impractical, if not impossible to replace the original light bulbs. Such radio are not useless, but they are more difficult to tune if not in an otherwise well lit room.
Yes, light bulbs are virtually everywhere, and that includes in our radios. However, if that light should burn out, it doesn’t mean our radio is gone. Either we can find a way to replace the bulb, incorporate an alternative to the burned out light bulb, or do without it.
Honestly, even knowing what I’d have to do to put an LED in to replace a light bulb that is no longer manufactured, I think I’d rather just go without the light. The way I see it, if the radio works properly, and I’m in an already well lit room, there is no need to replace something that doesn’t really provide anything extra.
If you really need that light, do what you can, if possible. If you can do without it, think twice before doing anything. You may save yourself some time and headache, and you might even find that proper bulb at a ham flea market. No sense damaging a classic radio unnecessarily.