I stopped listening to AM radio decades ago, but around 1998 I wanted to put together a crystal radio kit for my nephew in an attempt to get him interested in radio as I had been at his age.  As I was experimenting with plans for a good but easy kit, I was shocked to discover what the band had degenerated into.  Locally there are two Spanish language stations, two obnoxious "Christian" Fundamentalist stations and two stations that broadcast right-wing hate-talk propaganda day and night.  For a long time now, there has been nothing useful, entertaining or intelligent to tune into on AM (unless you speak Spanish).  I sincerely wish I spoke Spanish and liked Mexican music because the Spanish stations seem like "Islands of Sanity" in the otherwise sea of pure crap that's out there.  

     In America, broadcasting is all about feeding "the audience" what they want to hear so that they will listen to the advertisements.   English language AM panders to the ignorant and prejudiced people of my community who are afraid that their "superior" culture and foolish myths are under threat.   For comfort and reassurance that their distorted vision of "America" is always right, they tune in to this nasty stuff and the truth is, they are pretty loyal listeners.  Having all those dumb people listening so loyally really attracts the advertising dollar and so between hate-talk rants by Limbaugh, Savage Wiener, Beck and our own local wannabe, Andy, the airwaves are filled with the most asinine advertisements.  I mean, these are advertisements that, for the most part, should grossly insult the intelligence of the severely retarded.  

     For a long time now, I could not have cared less if AM disappeared altogether because I had my  FM radios for entertainment.  Well, all that changed when my long dormant interest in antique radios recently resurfaced.  While getting these old radios back working, I began to listen once again to some of our local trash and sadly rediscovered that, if anything, AM is even worse today than it has ever been.  Oh lord, I thought the hate-talkers were bad when Clinton was president, but now that we have a black-man in the White-house, in my life, I have never heard such over-the-top hatred.  It's just disgusting, but that's what our "local talent" wants to be fed, so there it is.

     So, what's a guy going to do when there is nothing decent to listen to?  Well, one thing I do is to wait until after sundown and on those few nights when the "skip" is in, I  tune in a great old station up in San Francisco, KGO radio.  Listening to KGO reminds me that once AM was worth listening to, but KGO isn't all that easy to hear.  Most nights the skip isn't there and you can't hear it at all.  Even when the skip is in, the signal is subject to fading, interference and noise.  Then there is the fact that even KGO plays endless commercials.  I must admit that KGO's commercials aren't quite as stupid nor do they assume the kind of listener stupidity that the local right-wing stations do, but those endless commercials really get tiresome and annoying.  Oh god, those "Cars For Kids" jingles just make me cringe, CRINGE!!

     Since writing the above, and for some months now, I am sad to report that even old KGO, a station that first went on the air in 1924 and was once the pride of Northern California, has joined the ranks of the AM zombies and is now hardly worth listening to.  For reasons of greater profits, the station has eliminated its program hosts and has gone to an "all news and traffic" format that includes recorded business reports from outside vendors.  Obviously the management does not care that the radio station has lost most of its listeners because, even with fewer listeners, the station is more profitable now that they have to hire so few employees.  In making the decision to downsize and eliminate most of the employees, the CEO of KGO certainly did not do the people of their community (or me) any favors, but in America today, squeezing out the last bit of profit is the highest of all virtues.  The responsibility to hire good people and to enlighten the community with good programming is rejected as a quaint old notion that no businessman today would give a second thought to.

OK, I've had my say regarding KGO.  Actually, what happened to KGO is just the final act in the death of English language AM radio in America and it illustrates my point.


     While meditating on what has happened to AM radio, I suddenly became "enlightened" and I would like to share my "enlightenment" with you in the form of some Noble Truths:

(1)   Listening to local AM makes my skin crawl after about two minutes.
(2)   AM radio is such a pain because all the local stations have been taken over by obnoxious religious and political propagandists.
(3)   There is an escape from what is so annoying about local AM radio.
(4)   You may escape this annoyance through broadcast band DX'ing late at night or, better yet, by having your own small
         AM transmitter and broadcasting your favorite stuff (or rebroadcasting your favorite FM station) to your old radios.  

     I think you will agree that having your own AM transmitter is pretty important, so it is the latter part of the Fourth Noble Truth that this article is all about.  

   There are all kinds of transmitters that one can buy.  These sets range from very cheap kits that have poor coverage to expensive sets that get mixed reviews.  On the Internet, you can find several plans for sets that you have to build up from scratch.  Well, I really hate "reinventing the wheel" when it comes to this sort of thing, so I searched around and found what I thought was "the most-est and the best-est for the least-est" in the form of the SSTRAN AM transmitter.The specs looked good and the seller said it was good, so I decided to get one.

       It's a long and somewhat unpleasant story (and now this product is no longer available anyway), so I'll just say that I never took possession of the transmitter and so I had to fall back on that old saying I had made up about doing things yourself if you wanted them done at all.  I searched the Internet for a project that I could quickly put together and there was this one site that kept popping up.  The site was Charles Wenzel's page where he described his AM transmitters.  The more I looked at Mr. Wenzel's designs, the more I liked them and finally decided that I would build something similar to one of his but with a tunable oscillator rather than a fixed crystal oscillator.  

     Even more than winding the toroid cores, laying out the components and their associated circuit strips was time consuming.  I started out by creating a rough sketch using the Paint program and with it as a guide, I was able to locate all the components on the perf board.

     I didn't build the board all at once because I wasn't sure I would be exactly on frequency.  After I had the VFO section done, I applied power and connected up my frequency counter.  I found I had too many turns on the coil, so I removed about 6 or 7 inches of wire and that brought the frequency up to where I wanted it.  I then built the rest of the circuit.  To tell the truth, when I went to wind the second coil, I measured out about 8.5 feet of No. 30 wire, counted the first 20 turns to the tap and then just kept on winding until I was out of wire without counting.  Things went much smoother on winding the second core.

Please see the above suggestion to use a FT37-43 cores to simplify winding the toroid coils.


     When I was done, I connected the board's audio input to the output of a portable radio and tuned to an FM station.  I connected up a little 12 volt power supply and a 10 foot piece of wire that I strung indoors from the light fixture in my back room, then I turned everything on.  It was with a lot of gratification that the transmitter worked and I was receiving the FM station in another portable AM radio.  I walked all over the house and I could hear the station everywhere, but the audio was a little muted unless I turned the volume of the transmitter's radio all the way up.  This wasn't good, so I put a tiny output transformer in and that worked almost too good as I had to turn down the output to keep from overdriving the transmitter.

     For a while I was a little concerned that I wouldn't be able to tune the output of this little transmitter for full resonance, but then I had an idea.  I took my Heathkit CR1 crystal radio, put a little stub of an antenna on it and then tuned down to where my transmitter was.  There it was, loud and clear.  I then simply tuned the variable capacitor at the transmitter's output until I got a peak signal from my crystal radio and with that, I was in tune.

     Mr. Wenzel warned me that I might not get good coverage from this transmitter, but with the transmitter connected to AC ground and an indoor antenna, I can hear the signal all over my house.  With a short outside antenna, I found that the signal is even better although not a huge improvement.

     Well, now I have a way of broadcasting something worth listening to.  Now I can use my restored antique radios once again.  It is my opinion that everybody with a restored and working antique radio should have one of these little transmitters so they can bring their old radios back to life.

     Here is the latest update.  Friday evening, my favorite FM station has a wonderful program on where they play digitally remastered versions of 1920s and 30s music recorded by the great artists of "The Jazz Age."   These artists  were once wildly popular and household names, but are today (with a few exceptions) completely forgotten.  I set up the AM transmitter in my back room and then listened in my living room to its signal using my beautiful 1936 Fairbanks Morse.  The music coming out of the old speaker sounded beautiful and the feeling I had was pleasantly strange.  The old radio, its old tubes and its speaker was once again playing the music that it had played when it was new and the person(s) listening back then would have heard the very same thing I was hearing.  I can't explain it, but it made me feel very strange -- but in a very good way.

     Yesterday afternoon and evening I had my 1930s Troy Radio on and listened to my favorite FM station as it was rebroadcast by my transmitter.  Part of the programming was old music and again that strange, but pleasant feeling returned.  It was kind of wonderful to, from time to time, notice that the excellent sounding audio was coming out of my ancient radio and look at it with its dial and tubes all lit up.  To think, the ancient tubes in my ancient radio were passing complex streams of electrons from their hot cathodes to their high voltage anodes and enabling me to hear these sounds.  I listened all afternoon and evening and if either the receiver or the transmitter drifted in frequency, it was much too little to possibly notice.

     Just recently I've been told about an Internet Radio station called Radio Dismuke.  They play the most wonderful music from the "Jazz Age" including the period commercials.  It is a wonderful station and I highly recommend piping it into your transmitter so that the tubes in your radio can stream patterns of electron flow just like they did in the 30s.  Besides that, you will love listening to what entertained our ancestors as much as they did.

     I am so glad I went to the trouble to build Mr. Wenzel's radio transmitter.

     You may have noticed that I am not using the same transistors that Mr. Wenzel specified.  The fact is, these circuits will work with just about any general purpose NPN transistor.  I am absolutely confident that the old 2N170 transistors, the type I used to buy in 1960 for a dollar apiece (about $15 in today's money), would work just fine in these circuits.

     In addition to the NPN transistors, you can use any depletion mode, N channel RF FET you want.  I used an MPF102 because they are so easily available, cheap and work great.  I've already mentioned that the T50-1 toroid cores may be substituted for -15 types and the diameter isn't important either as long as you wind for 280 microheneries and tap somewhere near the ratio I guessed at.  With regard to the capacitors, I used cheap, easily available disk ceramics and the electrolytic is an old surplus tantalum slug type I have a ton of, but a modern aluminum type would work just as well.

     I guess what I'm trying to say is that none of the parts are in the least bit critical or rare and they may be substituted for quite easily.  

     There is one thing that a builder might have trouble with and that is the stick-on copper strips.  I'm running a bit low on the strips I first got about 20 years ago, so I tried to find the website of the original manufacturer.  To my disappointment, I've discovered that they are no longer in business and it seems that nobody makes those strips anymore.  So, how would I build such a project if the strips can't be had?  Well, when I was looking around for substitutes, I discovered these neat perfboards that have a small island of copper around each hole.  To make the equivalent of my strips, all one would have to do is bridge the holes with a tiny drop of solder and TA-DA, you have your strip.

     To many people, building something like this project might seem like a daunting task.  I assure you that once you get started, the work goes very quickly and it gets fun as it picks up, but the key is to get started.  I would suggest that you first try this simple and easy experiment to see where it might lead you.  

     First, go and buy a perfboard with the plated holes as described above.  Take it home and with a small soldering iron and some good electronics grade solder, make up the strips as I have shown, but with solder bridges between holes.  Don't worry about getting it perfect because you can always remove solder bridges or add additional ones later if your layout isn't perfect.

     Look over your board and try to imagine where all the parts would go.  You will quickly see that it is no big deal putting  the parts in their respective holes, so then go out and buy (or, if your like me, scrounge) the parts.  When you have all or most of the parts, start stuffing the board, soldering the parts in and remove the excess leads with your cutters.  It's just that simple and when you have the board stuffed and soldered up, you will be eager to start the tedious part and that's winding the coils.

     Use one of the on-line calculators to determine the number of turns you will need and then add a few.  To make the tap, simply put on 20 turns or so, twist the wire so you have a pigtail about an inch long and then resume winding.  Yes, you will have to be careful the wire doesn't tangle and you will have to straighten out the inevitable tangles, but it only takes a few minutes to wind the coil and you will be so proud of yourself when you are done.  The second coil is identical and will be even easier to wind.  

     Please note: If you use the T37-43 cores as recently suggested, the winding is even faster and easier and the tap is only 2-3 turns with 28 turns, which is all that is necessary.

     Finish your board by soldering in the coils, use your own inventiveness to mount the tuning capacitors.  I choose 0-100 pF caps because of their size, but if you can get larger ones or even external tuning caps that you can mount on a panel, that would be even better because it will give you a greater tuning range.  You might want to just "tack solder" in the tops of the two coils because you will be taking turns off of them a bit later.

     It is your choice to mount the little matching transformer either on the circuit board or (as I did) mount it externally and run its leads to the board.  Mounting it externally with a drop of RTV and then running the 8 ohm input leads to the phone jack and the 500 ohm output leads to the audio input and ground of the board is really easy and convenient.

     Finally, apply 9-12 VDC and listen for your radios carrier with a AM radio.  Even with the VFO's trimmer down to zero, you may be too low in frequency, so unsolder the top and remove turns from the VFO coil until you are within the tuning range you want.  Yes, this is tedious and will take you some time.  When the VFO's coil is set right, take the same or maybe a few more turns off the antenna circuit's coil, connect the antenna you plan to use and peak the output with your antenna trimmer capacitor.  In the text I tell how I used a little crystal radio to do that, but you can do the same thing using a portable AM radio located dozens of yards away.  Perhaps you can turn up the volume and listen for it or have somebody tell you when it reaches its maximum loudness.  Anyway, you will figure it out.