Echophone Ec 1b Manual Arts
You might notice that the word 'COMMERCIAL' appears below to the name 'ECHOPHONE.' I do not know this for a fact, but I greatly suspect that the word 'commercial' was added to the brand name because these little radios were quite 'military' looking. By adding the word 'commercial' to the brand name, the radio would not be mistaken for stolen government property by overzealous and over-ignorant officers and NCOs. I know from my own experiences in the military, something like this is necessary to prevent the lower ranking men from being accused of the worst kinds of things by their so-called 'superiors.' The main customer for these radios were America's soldiers, sailors and airmen, but they were also very popular with small airfields and with the Civil Air Patrol during and just after World War Two. You see, from almost the beginning of aviation until the late 1940s, aircraft communicated with each other and with their airfields on shortwave.
Once your signal is passing through the ECHOPHON, pushing the Freeze button (1F) or sending a Gate High to the Freeze Gate Input (2F), will cause the ECHOPHON close the Echo chamber and hold the sound inside. The Freeze LED (3F) lights to indicate this state. While the ECHOPHON is Freezed the Pitch may be controlled using the Pitch parameters. Bongard retarder proofer manual arts; Vacuum petcock to manually clean; Nokia 2730c 1b manual transmission; 1997 toyota corolla workshop manual; Tecnicas organizativas manuales definicion de amor; Moticam 2300 manual high school; Mercruiser 454 service manual pdf; 2006 sportster 883 manual transfer; Johnson outboard motors manuals/1991. How I found and then restored a EC-1b shortwave radio 52 years later.Missing.
The shortwave circuits in these simple and inexpensive little radios performed quite well so that most airfield personnel preferred using an EC-1 for monitoring radio traffic rather than their more complex military radios. My EC-1 was used by the Civil Air Patrol and my EC-1b came from the Hancock Flying Field. The EC-1 in its Historical Context Echophone is a very old brand from the early days of radio and there are some beautiful old radios from that era. A young man named Halligan didn't have a lot of technical education, but he had big plans and he had saved his money as an employee of the ancestor of Radio Shack.
Halligan wanted to build shortwave radios for the ham radio market, but he needed permission from the Radio Corporation of America (RCA) to use their patents. David Sarnoff controlled RCA (with an iron fist) and he didn't give out licenses cheaply or to just any young guy who walked in.
After being shown the door time after time, finally Halligan bought the old Echophone company just as it was about to go out of business and for a small amount of money, he got the Echophone brand name and their RCA license. Halligan then began to manufacture ham radios under the brand name 'Hallicrafters' and used the brand 'Echophone' for his line of simple and inexpensive radios marketed not to hams, but to ordinary men and women who needed something to entertain and keep them informed while serving in the military. The original EC-1 was the GI's radio of World War 2 and it was manufactured by the Hallicrafters company under the brand name 'Echophone Commercial.'
It began production toward the end of 1940 and continued in production all through the war. This model radio was about the only commercial, non military radio that the government allowed to be manufactured during WW 2 and they did it for morale purposes, that is, to provide lonely, homesick and bored servicemen with entertainment. These rugged little radios have good short wave circuits so the servicemen and women could listen to shows, music and war news no matter where they were in the world. The EC-1 sold at a 'reasonable' price of about $20 (about a month's pay). Actually, for this quality of radio, $20 was a very low price and a lot of GIs got to own them either by buying them outright or receiving them as gifts.
The EC-1 radios were marketed to the GIs directly and through their families to be given as gifts. Ads for the radios appeared in magazines with a rather over the top campaign featuring a Private (later corporal) Hogarth. Hogarth was always shown as a hopeless nerd with coke-bottle glasses, but very popular with pretty girls who wanted to listen to his radio. Today we know better than to believe that a nerdey guy could attract girls with a short wave radio, but those were innocent times. Some of the advertisements that appeared in magazines were pretty silly suggesting that the GI owning one of these radios would become really popular with pretty young women regardless of how big a nerd he is.
My experience in life has taught me that women are anything BUT interested in a shortwave radio and that a nerd is a nerd is a nerd whether or not he has an EC-1. Still, parents wanted to give their serviceman something useful and entertaining and these radios were as nice a gift as it was possible to give. Most of the ads for the EC-1 directed to the GIs had a rather in-your-face sexual theme as the following suggests: As a nerd myself, I am rather proud of Hogarth for preferring his EC-1 to the sexy young woman, ha, ha. Hallicrafters calls it 'peeking' but it's really more like voyeurism Lots of wealthy Arabs have harems, but not one GI with an EC-1 and who hasn't a single oilwell to his name does.
What's ironic about this advertisement is that the EC-1 radios used early 1930's technology and the Japanese military radios were far superior to these little GI radios. No Japanese spy or soldier would give a hoot about its 'secret plans.' If anything, a Japanese soldier would have liked to capture one so that he too could listen to Tokyo Rose. From what I understand, Imperial Japanese soldiers were treated like dirt, absolute dirt by their officers and I'm sure they were forbidden to own radios. Any Japanese soldier caught with one of these radios would have his head cut off immediately by any number of officers who were only too willing to try out their Samurai Swords. What's also interesting to think about is how, less than 25 years earlier, during World War One, this same radio, with its sensitive and sophisticated multi-element vacuum tubes and superheterodyne design, would have seemed like it was from another universe come down on a space ship.
These little EC-1s were that much more advanced than the crystal and Fleming Valve radios in use during The Great War. There were some experimental Armstrong regenerative radios during that time and this same Edwin Armstrong was developing his famous oscillator and heterodyne circuits that would later show up in this radio, but even the best military radios of 1914-1918 could not come anywhere near the performance of the little EC-1 radio - and that is the understatement of the century. How I got a Second World War EC-1 Radio for Myself I really didn't need this radio. I already had an that was manufactured immediately after the war's end, but I wanted a genuine WW 2 model, so I when I saw this on eBay being sold for parts only, I put in a bid and won it for only $15.
It was a wreck all right. The dial was badly peeling and unreadable, the paint on the inside and outside of the case was terrible and the back panel was missing. There were a lot of other internal problems with this radio too that made it a candidate for the junk pile, but I was pretty sure I could restore it and the price was certainly right.
When I opened up my radio and took a good look at the internals, it was obvious that two different people had tried to repair it and the last person had wired parts of it incorrectly with very inexpert soldering. All evidence, deduced from the style of the replacement parts, indicated that the radio had not worked since the mid 50s. How I Restored My EC-1 With any project of this type, the first thing one needs is a good schematic. You need a good schematic to work to, to check any work done by others and to confirm that all replacement components and changes have been wired in correctly.
Over the years, it is impossible to know who did what to your radio and therefore it is necessary to check every circuit against a good schematic. If something is still wrong and the radio won't work, a good schematic is invaluable for troubleshooting and discovering what the problem is. I began the task of creating a good schematic by capturing fuzzy and hard to read schematics off of Internet sites. By the way, up until the fantastic development of this greatest factor in the spread of knowledge mankind has ever known (the Internet), schematics for these old radios were just about impossible to find. They certainly weren't available to just anybody back in the early 1960s when I first started working on these old radios.
After I had captured a schematic off of the Internet, I began to redraw it for clarity using the Paint program that came with my PC. I also went to the radio itself to double check any circuits I wasn't sure about. I then modified the drawing I had created to show certain changes I made to the radio and to show how the radio was really wired. This is the schematic diagram of the EC-1 showing how my EC-1 is wired today. The original.PDF drawing that I captured off the Internet was very useful as a starter, but eventually I had to completely redraw it to make it easier to read and to show some minor changes I made.
If you would like a free larger version of this schematic, and I'll send it to you. Please note how I rewired the power switch and replaced the power plug with a polarized plug. You must perform these modifications before beginning any work or your radio will present a deadly shock hazard. It is quite possible that the way my particular radio was wired is a result of a wiring error at the factory that was never noticed before. However, there are certain bypassing advantages to having the capacitor on the center wiper's circuit, but in actual operation, there is no real difference in performance and either way works just as well. If it was a mistake, that is why it was never noticed. In any event, I suggest you NOT replace or rewire your 100PF capacitors and leave them just as they were installed by the factory.
For those who have not had experience reading schematic diagrams, please be aware that a schematic is only to tell the technician HOW THE RADIO WORKS and not meant to tell exactly how the radio is wired. The schematic is ELECTRICALLY correct, but how everything is actually hooked up is another matter.
On the schematic it appears that a wire goes from component to component, but that is rarely the case in real life. As radios are actually wired, components are usually mounted on termination points that are jumpered to other points. These termination points may be terminal strips or they may be unused pins on tube sockets (that are almost never shown). For example, look at the AC rectifier tube in the in the lower right part of the diagram above. You will see that a 25 ohm resistor is connected to pin 8 with the other side of it going to the 47 MF capacitor. Actually, the other side of the 25 ohm resistor goes to unused pin 1 of the same socket, pin 1 is then jumpered over to pin 4 and from there the 47 MF capacitor is connected.
It is up to the technician to know enough about how all this stuff works to figure out for himself and trace out for himself the actual wiring from the schematic. Where the schematic equivalent and the actual wiring don't match, you have a miswire and you must fix it. If you find these diagrams confusing, you must realize that reading and understanding what is going on as shown by the schematic diagram is a skill that took many of us years and years and many hours of learning to master and you won't learn it overnight. As with any journey worth taking, what you see and learn while getting there is the best part.
A Little Essay on how These Radios Work A technical side note off of the subject of the story just in case you are interested The EC-1, as is nearly all radios made since 1930 to this very day is what its inventor, Edwin Armstrong, called a 'supersonic heterodyning radio' or, as we say today, a superheterodyne or simply a superhet. Armstrong came up with his superheterodyne while a major in the US Army signal corps in France during the Great War (WW 1). The British and developed a huge radio direction finding receiver for tracing German Army broadcasts and while operating this radio and while analyzing captured German radios, he observed some things that had been noticed by other early radio pioneers too.
Armstrong noticed and wrote a scientific paper on how it was possible for a radio signal to be heard on an entirely different frequency by a receiver if a nearby oscillator circuit was nearby. In other words, if a station was radiating a signal on 300,000 cycles per second (today we say Hz for short) and if a oscillator is tuned to 400,000 cycles, the radio station will be heard at both the original 300,000 cycles AND at 100,000 cycles. A lot of people had already noticed that and for them it was nothing more than an annoyance, but to Armstrong this opened up a world of possibilities.
If he could take one of those newfangled British Type R Valves and cause it to oscillate by building a circuit he had invented years earlier in 1911, he could mix its signal with a weak signal from a distant radio station to get a signal that landed in a more useful part of the radio spectrum. For example, if the radio station was broadcasting at what was then called 'the short wave band' up around 1,500,000 cycles per second, it was difficult to tune in just that one station and not have a lot of nearby stations also get into the radio. At that frequency and higher, it is really difficult to make radio filters, but at lower frequencies, say 100,000 cycles, really sharp filters are easy. By simply mixing the stations's 1,500,000 frequency with a tunable (Armstrong) oscillator that is operating at 1,400,000 cycles, a new frequency of 100,000 cycles is produced and can be fed into a narrow filter so that only the one station is heard and all other interference is blocked out. This new frequency he called the Intermediate Frequency or the IF and the series of filters and the amplifier tube to make up for the losses going through the filters he called the IF amplifier. The whole arrangement, including the filters (called IF transformers) and the amplifier tube is what is called the 'IF strip.' By the way, the filter transformers (or cans) I'm talking about are composed of a resonant circuit made from a coil and a capacitor and precisely tuned to the IF frequency.
The signal in this so-called 'tank' circuit transformer coupled to a second tuned circuit within the can. If it is the 1st IF transformer, the output goes to the IF amplifier tube, but if its the 2nd IF transformer, it goes to the 'detector' tube. Arranging transformers like this (called 'loose coupling') makes the filter very narrow which is what you want.
The amplified and filtered signal from the IF strip can not be heard because its frequency is beyond the range of hearing or, in other words, it is supersonic. To turn this supersonic radio frequency signal into something we can hear, it is fed into a detector tube (usually a simple diode like a fancy version of a crystal radio) where sound is recovered and then another tube where the audio (sound) signal is amplified and finally into a power amplifier tube where the sound can drive a loud speaker.
The earliest superheterodynes used low frequencies, but later frequencies around 455,000 cycles (455 kilo HZ) became standard for various technical reasons. You might ask, are there any other IF frequencies that will work and the answer is 'of course.' In my home made ham radio, I use an IF of 9,000,000 cycles (9 mega Hz), but way up there an ordinary radio frequency filter, such as Armstrong used, just won't work. To make my radio work with such a high frequency IF, I had to use a very sharp 'crystal filter' that relies on the very narrow filtering provided by the mechanical vibration of thin strips of quartz. By the way, it is a tiny version of those thin strips of quartz vibrating at a very precise rate that is the heart of the quartz movement in your watch and why even the very cheapest watch today keeps many, many times better time than the most expensive watches did when I was a kid. In my EC-1 the leftmost tube (12K8) is the mixer + oscillator tube.
The upper half of the tube mixes the signal with the frequency produced in the lower half of the tube which is configured as an Armstrong oscillator. An IF signal is created which is filtered by the 1st IF transformer and amplified by the next tube to the right, the IF amplifier (12SK7). The IF signal is filtered even more by the 2nd IF transformer and then the signal goes to the left hand diode section of the next tube, the detector tube (12SQ7). The audio recovered from the signal is amplified in the right half of this tube, goes through the volume control and then drives the audio power amplifier tube (35L6) which then drives the loud speaker. Of course, the EC-1 also has a BFO or 'beat frequency oscillator) tube (12J5) and what it does is create a IF signal that is very, very near the signal's IF frequency so that when they heterodyne or 'beat' together, a 'audio heterodyne' is produced so that a whistling sound can be heard.
The BFO is necessary to provide this service otherwise Morse Code (called CW) and single sideband voice signals can't be heard properly. I have also written an essay on the superheterodyne and go through the components step by step. The essay (and lots of other things) may be found in the radio section of my website. If you are interested, you might want to read that essay too.
Well, if you are still with me, let me get back to the story. Completely Removing the Chassis From the Case After I had a good schematic to work to, I began the manual task of restoring my radio.
Because of my radio's poor physical condition (it had been sold for 'junk' only after all), I need to completely disassemble it down to the last screw and rivet so I could have access to everything. As with my EC-1b, I had to grind out the rivets that prevented the chassis from being removed from the case. When I had the chassis separated from the case for the first time since my radio was built, I discovered a broken wire, well hidden in front of the band switch, that had never been repaired. This hidden defect would have prevented the AM broadcast band from working and therefore the radio must have been used exclusively for shortwave listening. Why it had never been repaired I can only guess.
My guess is that the owner either didn't want to spend the money to have it fixed or none of the shops he took it to could find the problem - maybe they didn't have a good schematic like mine to work to. It is altogether possible that the owner didn't care about the AM band and was interested in listening to shortwave only. If this radio had been part of an airfield or air search and rescue organization, the AM band would have been superfluous anyway. Replacing Components I fixed that broken wire on the band switch and I replaced all the old paper and electrolytic capacitors.
All the resistors (except the 330 ohm) and the three silver mica capacitors were in good condition, so I left them alone. Unless a resistor shows signs of serious overheating, it is my opinion that it should be left alone as none of the resistors values are critical and they don't vary all that much over time. The 330 ohm resistor is only a 1/2 watt unit and it usually burns up when the lamp burns out. If you replace the 330 ohm resistor with a two or three watt unit, you will never have to worry about this resistor going out again.
By the way, this model of radio was designed to use low cost components and therefore there are only three silver mica capacitors in the whole radio. Even these silver mica capacitors are in circuits that are not in any way critical.
One of the silver mica caps (the 50 PF) is used for coupling and the other two (100 PF) are used for bypassing. All capacitors may be replaced by ordinary disk ceramics - yes, even the silver mica caps. Replacing silver mica with silver mica is better, but I doubt you would be able to notice any difference in performance or any frequency drifting if you used ceramics. By the way, the only reason silver mica capacitors were used in 1940 was because low value capacitors (50 to 100 PF) were only available in silver mica. Speaking of capacitors, for this radio I used disk ceramic capacitors I already had and they work just great. My last rebuild was a 1937 farm radio for a friend of mine and for the first time I used metalized mylar caps. Too tell the truth, I liked working with the mylar caps better because of the long axial leads more easily span the large spaces left after the old paper/wax caps are removed.
With regard to performance, I don't believe it makes a lick of difference what kind of cap you use as long as it's not a paper/wax cap. While I'm on the subject, let me suggest that you make up a list of all the caps you will need to replace, send for them and then assemble everything you will need into a kind of a kit. Your kit should also include gripping tools (I use hemostats), a good soldering iron, solder-sucking braid (I also use a vacuum solder sucker), a jar of extra rosin flux (I don't know what I'd do without my extra flux) and a roll of electronics grade rosin core solder. Once your kit is assembled and you begin your work, I think you will be amazed how quickly the work goes because these radios are so very easy to work on. For safety sake, I put in a polarized plug and connected AC Neutral to the chassis as described in the (which I urge you to read and follow).
I relocated the power switch so that the AC Line voltage switches the filament string and rectifier circuits on/off all as described earlier in the safety section. All the insulating grommets were replaced so that there was no electrical connection between the chassis and the outside case besides a.02 MFD bypass capacitor and 470 K resistor shown in the schematic.
Echophone Ec 1 Schematic
The rubber washers that were used to mount the tuning capacitor deck were in terrible condition and it is impossible to obtain exact replacements. For a while I thought remounting the tuning deck was going to be a 'show stopper' but by cutting down ordinary rubber grommets to fit, I got the deck mounted perfectly. Getting My EC-1 to Operate for the First Time in 50 Years When I turned the radio on for the first time in probably 50 years, I was gratified, but not too surprised that it immediately came to life because I had done my homework and had checked and rechecked every circuit and wire against the schematic before plugging it in. As I tried to tune in stations on the AM band, I had a feeling of great disappointment because the radio performed very poorly and sounded very weak. I thought I was going to have to buy a new tube or two, track down some bad resistors and generally spend a lot of time troubleshooting the set, but a simple IF alignment really brought the little radio alive. All of a sudden, this old radio was 'hot,' bringing in stations loud and clear.
Somebody, a long time ago, must have been messing with the IF transformers in an attempt to get the radio working and had them badly out of alignment. Once the IF was aligned and I was receiving AM signals strongly, I made a connection to an outside antenna and found that the radio was 'hot' on both its short wave bands too. A horrible crackling sound I was so pleased by how well my radio worked that it took me a day or two to notice that it made a horrible crackling sound as I tuned toward the bottom of the dial on the short wave bands. I hadn't noticed it earlier on the AM band because there are no local stations that low on the dial. Since the crackling only showed up at a certain place on the dial, that meant I must have a bad spot in my tuning capacitor. Bad spots are almost always caused by a bend in the thin metal fins of the tuning capacitor. Bent fins can happen when somebody sticks their hand deep in the radio to pull out a tube or replace the dial lamp and brushes up against the tuning capacitor.
Because the tuning capacitor is so vulnerable to damage, I highly recommend turning the dial to the lowest setting so as to close the tuning capacitor whenever checking tubes or changing the dial lamp. It turned out that my radio had been damaged even more severely than a simple bent fin. Somebody must have dropped something on my radio while the lid was off and had fractured the phenolic insulator that supports the stator plates of the capacitor (see the picture above). Oh my lord, this was serious and my first thought was that I'd have to somehow replace the tuning capacitor.
It then occurred to me that a modern, very strong glue would work in this application, but I'd have to hold the parts of the insulator very carefully in alignment while the adhesive was setting up. I was able to do this, but it took an elaborate series of hemostats clamped on at various locations to keep everything lined up properly. Once the adhesive hardened, I was pleased with how solid and permanent the repair was, but the crackle was still there. I got out a strong light and a magnifying glass and tried to find the problem, but I just couldn't see where the plates were touching no matter what I did. Finally I got desperate and decided to put a 12 volt, 3 amp power supply across the plates. I slowly closed the plates while looking for a big spark.
Well, that worked great, I saw the spark and I was able to see just exactly where it was coming from. Knowing just where to look, I now saw the bent fin that caused the shorting and it only took a minute to carefully bend the fin out of the way. I've never had a problem with crackling since and I expect my repaired tuning capacitor to last at least another 60 years. Getting the radio to work better than it did in the 1940s Now that I had the radio working well, I tackled the beat frequency oscillator (BFO) stage. Turning the BFO switch on or off made no difference and it appeared to be inoperative.
A BFO that doesn't work could be due to a bad component or a bad tube or due to being badly out of tune. First thing I did was to see if the BFO circuit was oscillating and to test that I connected my HP frequency counter to the plate of the 12J5 tube (pin 3). The numbers on my counter indicated that the oscillator was working, but it was way off frequency. I adjusted the trimmer capacitor until the BFO was at 455 KHz - which is what the IF transformers had been adjusted to.
The BFO was now operating and I could hear the 'dots and dashes' of Morse Code as the BFO was designed for, but when I tuned in ham radio people talking on single side band (SSB), I discovered that my BFO's ability to demodulate those signals was so poor as to be useless. The truth is, the EC-1 radios were manufactured before there was such thing as SSB and so the original factory configuration of the BFO needs to be modified before they can demodulate SSB properly. Now, one of the really nice things about the EC-1 series of radios is that they have a 'real' BFO operated by a triode tube and any redesign for SSB should be fairly easy and, you know, it was fairly easy. To make the BFO operate satisfactorily, the first thing I did was to relocate the point where the signal is tapped off from the oscillator. Of all the dumb places to tap off a signal, the original design tapped it from the grid of the 12J5 oscillator tube thus modulating the tube with stray AC hum to produce AC hum on the BFO signal. I simply moved the tap point to the anode of the 12J5 tube (a low impedance point).
That simple move cleared up the BFO's hum problem and that made listening to Morse Code (CW) and SSB much better, but it still demodulated SSB poorly and obviously the BFO needed further modification. The original design calls for the BFO signal to be coupled to the anodes of the 12SQ7's diode section (pins 4&5) using a 'gimmick' capacitor consisting of wires twisted together.
I found that the BFO signal 'injected' there caused the stronger SSB signals to be demodulated very poorly or not demodulated at all. These radios use a simple AM detector not originally designed to demodulate SSB.
An AM detector (which is what the diode section is) must have a 'carrier wave' for the sidebands to 'beat' against to produce audio. Since there is no carrier transmitted with SSB (or CW) signals, the BFO supplies it, but injecting the BFO carrier at the diodes of the 12SQ7 is just not enough. I found that if you supply your artificial carrier at a low level before the IF amplifier input (the 12SK7, pin 4) then the diode detector works quite well at demodulating SSB.
Echophone Studios
The only thing is, you have to be careful because there is a lot of amplification done by the IF tube and so you must very lightly couple the 455 kHz BFO signal to it or you will 'swamp' the tube with too much signal. I had to locate the end of the wire coming from the BFO quite a ways from pin 4 (the grid) of the IF amplifier for it to work properly. Once the wire is in place though, the BFO's operation is very stable and it works great. The reason the location of the wire with the BFO's signal on it is so critical is because whole idea is to inject as much signal as possible without 'swamping' the IF tube.
If you don't inject enough signal, the really strong SSB signals are not demodulated properly and they sound terrible. When the signal is too close to pin 2, you will notice that the radio goes 'numb' when you turn the BFO on. If that happens, it is because the tube is being overloaded, so you must relocate the wire away from pin 2 until it works properly. If everything is adjusted properly, there should be a distinct increase of a 'rushing' white noise sound when the BFO is turned on. You will have to experiment for yourself to find the optimum location. By the way, a couple of weeks after bringing the old radio back to life, the original IF tube that came with the radio (probably the original tube) burned out, but again thanks to the Internet, I had a replacement tube in just three days and at a very reasonable price. The new tube is obviously 'hotter' than the old tube because I had to move the BFO wire even further away from pin 4 to keep the IF from being swamped.
I repainted the case using a 'Antique Bronze' color that closely matches the original color and (if I say so myself) the case now looks just great. Finally, I made a new back out of thin Masonite and I restrung the tuning mechanisms (with heavy twine meant for stitching leather) before putting everything back in the case and screwing it all together. By the way, once you have rewired the on/off switch and have made the radio safe with the polarized plug, you really don't need to have a Masonite rear cover, but might just want to leave the back open. Of course, having a back makes the radio more original and 'finished' looking, but the back was there originally only as a safety device and you really don't need it anymore. If you insist on being stubbornly foolish and acting dangerously by not rewiring your radio, you better have a a Masonite back. As mentioned earlier, the original dial face was badly peeling and unreadable so I drew a new one using my PC and the Paint program. I simply printed it out on paper (trying to match the color of the original dial face) and pasted it on to the backside of the dial plate.
I covered the original dial face with varnish to protect it from further deterioration and turned the plate around to show this face. If I say so myself, installed in the radio, my homemade dial face looks really great and very 'factory.'
Some Antenna and Other Tips These radios did not come with a built in loop antenna for the AM broadcast band as did almost every other AM radio of its era. They were designed as a long range, more technical general coverage radio and as such they need an outside wire antenna of some kind. The fact is, these radios are very 'hot' if used with a wire antenna of as little as 20 feet, but for great performance (especially on the short wave bands), the best antennas are as long as you can make them. When putting up an antenna, try to go vertical as quickly and as high as you can before going horizontal to minimize noise pick up. When working at heights, please be careful. Try to keep the antenna away from noisy devices like motors and especially fluorescent lights. If you have pieces of metal that rub together in the wind, try to clamp them down otherwise they will generate noise.
You will notice on the back of your radio there are three screw lugs for the antenna system. When using an untuned long wire antenna, only the A1 lug should be used and that little jumper tab should connect A2 to the GND lug.
The A2 lug should only be used with a tuned and balanced antenna system that is beyond the scope of most users. I would suggest that you not try to connect the GND or the A2 lugs to an actual ground as you may introduce some serious noise and hum that way. Anyway, the wonderful thing about these old radios is the opportunity to experiment around and find out what works best for you with what you have. Here is a nice tip from my EC-1b page: By the way, one really great way to find broadcast stations on the shortwave bands is to turn on the BFO and listen for loud 'whistles' as you tune up and down the dial with the main tuning control. When you hear a whistle, tune as close to 'zero beat' as possible and then turn off the BFO.
Trim up the signal with the bandspread control and you have a nicely tuned in shortwave station to listen to. For me, this is probably the most useful thing a BFO does. Some Final Words Regarding my EC-1 Today This radio uses variable capacitors for its bandspread and this alone makes it somewhat superior to my later EC-1b. This is my favorite radio for listening to shortwave broadcasts because it is so quick and easy to tune through the bands and see what band is active. I have the radio placed next to my Personal Computer for convenience so that when I get tired of playing on the Internet, I just snap on the EC-1 and see if anything is happening on KGO San Francisco on AM or anything on the short wave bands. With a 'real' BFO connected the way I have it, I can listen to AM, Single Side Band and Morse Code and it sounds fine regardless of which kind of signal I'm listening to.
By the way, these radios only draw 30 watts, so they don't get hot and they don't waste a lot of electricity. Have fun, I know you will. Recent addition: Just recently I was away from home for about a week on a remote ranch so I played Corporal Hogarth and brought my EC-1 with me.
It was just the right size to toss in the back of my pickup truck along with my food and other gear. Once there, I strung a wire out to a tree and tuned in to the short wave bands at night. It really was fun having this old radio with me and I'm very glad I brought it along. I was all by my self out there and it was good company, but I am very sad to report that it failed to attract any pretty young women. I've been thinking of writing to Hallicrafters about that.
Allan Hancock About 35 years ago I had the unique good fortune of spending about an hour with Captain Hancock's former science adviser and this man told me things that I found very impressive. Captain Allan Hancock was a brilliant man, an adventurer, a scientist and a true patriot who used his wealth in the service of his country and who's legacy endures at Hancock College and the Marian Medical Center. Together with the renown geologist, William Orcutt, he revolutionized Pleistocene Geology and brought California's extinct saber tooth cats, Mammoths and hundreds of other strange and wonderful creatures out of his tar pits and into museums. Allan Hancock's title 'Captain' was honorary and it was bestowed on him because, among other polymath interests, he commanded a large seagoing oceanographic ship. His scientific interests took in everything on land, on the sea and especially in the air.
Captain Hancock was a man very much like Howard Hughes only he was much more down to earth. To say the least, he was a man of real substance rather than a lot of show. Like Hughes, he was an enthusiastic promoter of aviation and early on he recognized the importance of trained aviators to our country's defense. Immediately before World War Two began he unsuccessfully lobbied the government regarding the need for pilots to man the war planes he knew would be needed for the war. Even after the war began he could not get immediate funding to begin a primary flight training school on the West Coast, so, with his own money, he began the flight school at Hancock Field. During World War Two, thousands of student pilots received their primary flight training at Hancock Field and, in its heyday, it was an extremely busy place, vital to America's war effort.
By the way, back around 1979 or so, when I was active in ham radio, I had a wonderful conversation with another ham radio operator on the 80 meter band. I can't remember where he lived, but I think it was San Diego, CA. I was really pleased to learn that he had been a student at the Hancock Flying Field during WW 2, so I told him that I lived within spitting distance of the place and had played there as a kid. He told me how he had arrived by train at the Guadalupe Station, but had to wait a couple of hours before the trolley would take him the 12 miles to Santa Maria and then on to Hancock Field. With hours to kill, my friend went into a bar to have a beer and while away the time. Most of the bars then and now are Mexican there in Guadalupe and of course this one had a big portrait of some very important looking Mexican President.
My friend then says to the bartender ' so, when did he get assassinated?' Well, that was the wrong thing to say in a rough town like Guadalupe (still is), so after a very angry exchange of words, my friend was chased out of the bar and had to run for his life with a gang of angry Mexicans after him. He then hid in terror while the patrons of the bar went looking for him. Finally the trolley to Santa Maria arrived, my friend ran out of his hiding place, made a beeline for the car and rode it the 12 miles to his new life as a student pilot. We didn't have time before the 80 meter band collapsed and ended our conversation (called a QSO) for him to tell me of any of his wartime experiences as a pilot, but obviously he was one of the lucky ones who survived the War.
Hancock Flying Field Junk Pile, circa 1958 The Flight School operated there at Hancock Field all throughout the war, but by the mid 1950s, the need for primary flight training had decreased substantially and government funding of the school had run out. Sadly, the old field and its associated flight school had lost its original purpose and something new had to be found for its facilities, but such a change takes time. Even as late as 1958, there were still aircraft parked on Hancock Field. As they were dismantling the flying field and getting it ready to turn it into today's Allan Hancock Junior College, the workers created wonderful piles of period junk. For a kid like me, rooting through this stuff was 'hog heaven' and no 'pig in shit' was happier than me going through the junk piles. You see, by 1958 my dad had retired from the Navy and we were living in a house not a quarter mile from the Allan Hancock Flying Field. What a wonderful adventure it was to sneak over to Hancock Field, go through their trash and fish out the most marvelous stuff.
What was even more marvelous was sneaking inside one of the multi engined observation aircraft that were being dismantled right on the runway. I'd put on a flying helmet I had salvaged from the junk pile, put on my headphones and, like the Blue Bird of Happiness, I'd go flying far over the ocean blue, bound for places I'm not known to. Back in those days, adults didn't seem to be so rule-bound and didn't run kids off like they do today. It seemed that as long as a kid didn't attract attention by doing anything destructive or dangerous, you were ignored and allowed to have your youthful adventures.
Of course, what are those adventures compared to kids today playing World Of Warcraft on their home computers? While piloting my big plane with its Plexiglass nose, I'd go on patrols looking for Emilia Earhart and Japanese Battleships and of course I have on my headphones and would be in radio contact with 'base command.' In my imagination, I'd be reporting back all the adventures I was having by short wave radio. Of course, my trusty plane no longer had its engines and was being slowly disassembled, but there was still enough of it left to excite my imagination. A Little Hallicrafters History The EC-1 radios were made by the Hallicrafters radio company, but marketed under their Echophone brand. The EC-1s are historically important because they were manufactured as a 'GI's Radio' and as such, they were marketed to soldiers, sailors, marines, airmen and their families. More often than not, it was the EC-1 radio that our GIs used when they listened to Tokyo Rose, Roosevelt's & Churchill's speeches, wartime news, radio comedies & dramas and the very popular big band music of that era both on the broadcast band and especially on short wave.
They were very extensively used in a semi-official capacity too. Probably every flying field and Civil Air Patrol unit had at least one of these radios because they were cheap, available through the government and worked well at bringing in the shortwave aircraft broadcasts that were used to communicate with the flying field and during search and rescue missions.
The reason these radios were so popular is that they were a lot smaller and much easier for untrained operators to use than were the more elaborate military radios of the era. Just as importantly, even small, local radio shops had technicians who could fix them and get tubes and other parts for them. I am sure there were many 'better' military radios that sat unused because nobody knew how to operate them or fix them when they stopped working. As I mentioned earlier, my particular EC-1 is the 'B' model which went into production immediately after the war ended and in the very month I was born.
Although my particular radio was not manufactured during the war years, it obviously had been used in conjunction with operations there at Captain Hancock's flying field in the years immediately following the War and until the flying field was closed in the mid 1950s. It, like so many other pieces of flying field related hardware, was simply thrown on the junk pile after it had stopped working and there was no need for it any more. The fact is, the post-war 'B' model is a slightly cheaper version of the wartime EC-1, but it does have a noise blanker and, that might be called an improvement over the older model.
The thing that cheapened up this model was Hallicrafter's decision to use a movable ferrite slug for its bandspread tuning. I'm sorry to say it, but the ferrite slug tuning is definitely inferior to the capacitor tuning of the earlier wartime model. I spent a considerable amount of time and care adjusting the mechanism of my radio's bandspread tuning and now it works quite well - almost as well as a 'real' capacitor bandspread, but the truth is, the older capacitor tuning system of my wartime EC-1 is smoother and more precise. The two models have other minor differences too.
They use different methods of generating the local oscillator and BFO signals (with Hartley rather than Armstrong oscillators) and they use slightly different types of tubes for the mixer/oscillator and the BFO. The original EC-1 does not have a noise blanker, but the diode section of the 'B' model's BFO tube functions as one. I have found this noise blanker creates a lot of audio distortion on strong signals and so it is useful only when trying to listen to very weak, very noisy signals. These noisy signals are not normally ones you would want to listen to, but during those rare times when you want to pull a weak station out of the noise, it can work quite well. Even though the two models use slightly different tubes and different types of oscillator circuits, both the EC-1 and the EC-1b pull in shortwave signals equally well and both are pretty 'hot' little radios when it comes to pulling in stations. Both models are stable and have surprisingly little drift for such simple radios once they are warmed up. In practical operation, there is really no difference between the EC-1 and the EC-1b radios.
My EC-1b Radio Project How I First Acquired my EC-1b Radio I have no idea how long my radio had been in Captain Hancock's junk pile before I rescued it, but I know that it had been thrown in upside down and it had been subjected to some burning. I know this because the beeswax that coated the paper capacitors was melted off and puddled on the underside of the chassis. The heat had also damaged the plexiglass window over the dials and they were obscured. The inside front of the radio was covered with an engine sludge that had thickened into a tar. Exposed to the weather for an unknown length of time, the the outside case and parts of the inside chassis (not covered by engine sludge) became badly rusted and corroded ( even the metal tubes were all rusty ) and the radio was missing its metal top & Masonite back cover.
Yes, it was a wreck and a fit candidate for the junk pile, but as horrible as it looked, I took it home anyway and stored it in the family garage with no particular plans for it. When we moved to the house I'm presently living in about the year 1960, I placed the shell of the radio in the garage and there the junked radio sat in the same place, untouched for over 50 years. My younger brother can't remember a time in his childhood when it wasn't there. After my parents died I bought the house from their estate, but left most everything in the garage undisturbed, but just a few months ago, in 2011, I rediscovered the old radio while cleaning out the garage. It looked horrible and I wasn't sure I could restore it, but a few months earlier I had good success and a lot of fun restoring my old S-38b radio, so I thought I'd give it a try. I really wish now that I would have taken some photos of the radio looking the way it did because it's hard to describe just how bad it looked at that time. I didn't take any photos because I was afraid I wouldn't be able to restore it and if I failed to restore it, I didn't want pictures to remind me of what I had failed to do.
Because of the terrible shape it was in and all it had endured while on the junk pile, I knew it was going to be quite a challenge to bring it back to life and t he following is the story of just how I did it. Restoring the Radio Physically I began by completely disassembling the radio down to the last screw and rivet so that I could get at all the insides.
I needed to do that in order to clean out the sludge and repaint everything. All the front switches had been riveted on and that prevented the chassis and case from coming apart. I had to take a small diamond ball grinder and grind each rivet out one by one. Once the chassis was out of the case I scraped out and then scrubbed out the sludge with solvents, I sanded and carded off the rust with wire brushes, I repainted the case, cleaned the corrosion off of the tuning capacitors, removed all the sludge between their plates and then freed up the tuning mechanisms. Finally, I restrung the tuning capacitors and the bandspread slug mechanism with the same dacron string I use for leather stitching.
Once the fogged up front window was off, I discovered that the main tuning dial pointer was missing. My heart sank when I discovered that and for a while I thought that this missing pointer would be a real 'show stopper' because where in the world would I get another pointer. I was in a funk and thought that it was useless to proceed any further, but then it dawned on me that I could make a reproduction dial pointer out of hardwood on my lathe and then paint it so it looked exactly like an original. It turned out to be pretty easy to do and I am absurdly proud of how well my homemade pointer turned out. The pointer I made is on the left with the factory pointer on the right. Pretty good reproduction for an amateur, wouldn't you say? The missing metal top was something I couldn't make myself so I had a top made at a local sheet metal shop (for $20 - the original price of the radio new).
The original back panel had been made of Masonite so it was easy to cut out a panel of that material, drill and grind out the ventilation and access holes and make it look like an original. The truth is, if you perform the very necessary safety wiring modifications, you really don't need a back panel since its only function was to protect the operator from electrical shocks. Once the radio is rewired for safety, the need for a Masonite panel goes away. Of course, having a rear panel is necessary to make the radio look original and it does look a little 'unfinished' without its rear panel. The truth is, if I was to do it over again, I don't think I would have made a rear panel. The outside of the case was terribly rusted and there was no way I could salvage the original lettering.
I worked hard to sand and wire brush the rust off of the case and when it was ready for painting, I searched for a 'battleship gray' paint that matched the original. The original paint was gray, but it had a slight blue tinge to it that is impossible to match. I tried various paints and they all looked terrible, but finally I found a 'textured gray' outdoor paint that was not only rugged and chip proof, but it was close enough to the original color to please me. My biggest regret is that I have been unable to reproduce the white lettering on the front panel. I had to resort to black stick-on lettering and I think you will agree with me that it looks really bad. Someday I hope to restore the lettering as it should look and if you can help me or offer any suggestions, I would greatly appreciate it. AN IMPORTANT SAFETY NOTICE!
One of my main goals was to redesign this 'hot chassis' radio so that it would be safe at all times, so I replaced all the rubber insulators and installed a grounded AC plug. I made sure the chassis would always be at AC Neutral and the case would be securely grounded. I decided that creating an isolated return bus, as I had done for the S-38b, was a design over-kill that wasn't at all necessary, so I satisfied myself with insulating the chassis and securely tying it to AC Neutral through the use of a polarized, grounded AC plug. The way I have my radio now, it is now a very safe radio and with the case grounded as it is, it would probably be safe to use in the bathroom (although I certainly don't recommend doing so). I am so confident in my radio's safety that I would think nothing of leaving it on day and night unattended.
I have no fear it could possibly overheat (it only draws 30 watts) or that the radio could possibly start a fire. What I did to get the old radio working again. I believe that the Internet is the greatest development for the spread of knowledge since the development of writing, so thanks to the Internet I was able to capture a useful copy of this radio's schematic diagram. I spent a lot of time carefully redrawing the schematic for clarity and to draw in all the changes and corrections I made and needed to make. Without a good schematic to work to, the job of restoring or repairing one of these old radios is impossible, therefore all the many hours I spent redrawing this diagram for clarity and accuracy was well worth it. And here I am offering it to you for free.
With the help of the schematic, I replaced all the capacitors except for the five silver mica capacitors, which almost never need replacing. All the other capacitors were in horrible shape and would have had to be replaced even if they weren't already half melted.
All the resistors were still good as they almost always are, so none of them were replaced except the 330 ohm resistor that is almost always found overheated because of a failed lamp. If the 330 ohm resistor is replaced with a 2 or 3 watt unit, you won't ever have to replace it even if your lamp fails. One thing that I noticed was that somebody had tried to replace the electrolytic capacitors way back in the mid 1950s and had made some wrong wring connections. The workmanship of the soldering was really poor too, so obviously the radio had been worked on by somebody who didn't know radios. Of course the radio wouldn't work with these mistakes, so that's probably why the radio was in the disassembled state I found it in and why it had been put on the junk pile in the first place. By the way, the total bill for all the replacement parts I needed was less than $20.
Completing the Project and Plugging it in for the First Time in 50 Years After I had all the new parts in and I had the chassis back in the case, it was time for 'the moment of truth' - that is, for me to turn on the radio and see if it would actually work once again after all it had been through. Now, I had really done my homework and had triple checked all the wiring and all the circuits in the radio before I even plugged it in. The very first time I plugged it in and turned it on, sound came out of the speaker.
To tell the truth, I was sure it would work, but I was mildly surprised (and pleased) that it worked so well and played so loudly because I thought I'd have to do some troubleshooting and maybe replace an ancient tube or two and maybe do a lot of alignment work on the RF and IF sections. But there it was, able to tune in stations loud and clear after this radio had been silent for over 50 years. I was somewhat sobered by the thought that here I am, the first person to hear this radio since it had last been used by the people there at Hancock Field over 50 years ago. From the period from about 1946 until the mid 1950s, many people must have used this radio both for entertainment and for official flight operations. Now, after all this time, all those people, including Captain Hancock, a man who had done so much for his country, have died and are resting somewhere mostly forgotten. Yes, all those hot-shot pilots and adventurers in their dashing uniforms and their leather flying jackets and jaunty military caps, those eager young men going off to war are all gone and who remembers them?
Gone too are the huge aircraft with their powerful engines, and yet, here's this inexpensive little radio with its outlandish collection of metal parts, wires and vacuum tubes. With everything else lost in time, it alone has somehow endured and it has been brought back to life once again. It is not mute because voice and music still plays through it, but it can not tell us of the people and times it has been a witness to. OK, enough of all that mushy sentimental stuff, back to the story.
Getting the BFO to Work and Improving its Performance As bad a shape as this radio was in because of all the scorching, rusting and exposure to weathering & time, amazingly, all the circuits were still pretty much in tune. I ran a complete tune up on the radio, but it was so close to an ideal tune that I didn't really improve it's already 'hot' performance.
Now that the radio was working, I started to test and restore the Beat Frequency Oscillator (BFO) stage. There was a very fine broken wire in the tapped inductor, but I was able to find the end under the wax near where it had been soldered to its lead. I was able to free enough slack to resolder it to the lead and after that the BFO worked, but was way out of adjustment. The redrawn schematic showing the changes and improvements I made to the original design. E-mail me if you want a larger copy (for free). One of the great things about the EC-1 series of radios is that they do have a 'real' beat frequency oscillator, but the original configuration of the oscillator tube and its circuit doesn't work all that well.
On operating the radio, I found that the radio's original BFO design made tuning in and listening to Single Side Band (SSB) signals somewhat difficult. I slightly modified how the BFO signal was tapped off from the oscillator circuit (at the lowest impedance point of the Hartley Oscillator tube's cathode) and changed where the BFO signal is injected. I immediately noticed a vast improvement in audio quality, especially on single side band.
Locating the end of the wire that radiates the BFO signal is somewhat critical. You should not couple to pin 2 of the 12SL7 IF tube too closely or you will 'swamp' the tube by overloading it. If your radio gets quiet when you turn on the BFO, you need to move the end of the wire away from pin 2 until it sounds right. In fact, the 'rushing' white noise sound should increase when you turn on the BFO. You want a strong signal injected here to match the strength of strong signals coming in on single sideband and CW, but too much will overload the IF tube and cause you to loose signals. If you need to change your IF tube for any reason, you might want to readjust the location of the end of the BFO wire.
Here is a paragraph from my EC-1 page explaining why modifications to the original BFO design is necessary: The original design calls for the BFO signal to be coupled to the anodes of the 12SQ7's diode section (pins 4&5) using a 'gimmick' capacitor consisting of wires twisted together. I found that the BFO signal 'injected' there caused the stronger SSB signals to be demodulated very poorly or not demodulated at all. These radios use a simple AM detector not originally designed to demodulate SSB. An AM detector (which is what the diode section is) must have a 'carrier wave' for the sidebands to 'beat' against to produce audio.
Echophone Ec 1b Manual Arts Program
Since there is no carrier transmitted with SSB (or CW) signals, the BFO supplies it, but injecting the BFO carrier at the diodes of the 12SQ7 is just not enough. I found that if you supply your artificial carrier at a low level before the IF amplifier input (the 12SK7, pin 4) then the diode detector works quite well at demodulating SSB. The only thing is, you have to be careful because there is a lot of amplification done by the IF tube and so you must very lightly couple the 455 kHz BFO signal to it or you will 'swamp' the tube with too much signal. I had to locate the end of the wire coming from the BFO quite a ways from pin 4 (the grid) of the IF amplifier for it to work properly. Once the wire is in place though, the BFO's operation is very stable and it works great.
Most of the time the BFO doesn't need adjusting, but if yours is not working properly, you can adjust it. It really helps to have a frequency counter and set the output of the BFO to 455 KHz, but a quick and dirty method is to tune in a station for maximum strength. That way, the station is very near the center of your IF transformers' pass band. Turn on the BFO and tune it so the squeal gets lower and lower in pitch until it disappears or is just a low hum. That's all you have to do and you should not touch it ever again. By the way, one really great way to find broadcast stations on the shortwave bands is to turn on the BFO and listen for loud 'whistles' as you tune up and down the dial with the main tuning control.
When you hear a whistle, tune as close to 'zero beat' as possible and then turn off the BFO. Trim up the signal with the bandspread control and you have a nicely tuned in shortwave station to listen to. For me, this is probably the most useful thing a BFO does. A Highly Specialized Modification Here is something that is pretty specialized and I don't expect many people would want to do this. For test and comparison purposes, I wanted the Local Oscillator to be shut off when the radio is in the 'standby' mode (like it is in the EC-1 radios), so I put a coupling capacitor in series with the Hartley Local Oscillator coils & the cathode of the 12SA7 tube. I connected one side of a 2.5 millihenry choke coil to the standby switch and the other side of the coil to the anode of the 12SA7 so that electrons supplied through the chassis will flow to the anode (pin 6) when the standby switch is in the 'operate' position. The modification has absolutely no effect on the performance of the radio, but it allows me to have two radios turned on with one on standby without the local oscillators 'talking' to each other and messing up side-by-side comparisons of the two radios performance.
For most people, this is a completely unnecessary modification. Some Antenna and Other Tips These radios did not come with a built in loop antenna for the AM broadcast band as did almost every other AM radio of its era.
They were designed as a long range, more technical general coverage radio and as such they need an outside wire antenna of some kind. The fact is, these radios are very 'hot' if used with a wire antenna of as little as 20 feet, but for great performance (especially on the short wave bands), the best antennas are as long as you can make them. When putting up an antenna, try to go vertical as quickly and as high as you can before going horizontal to minimize noise pick up.
When working at heights, please be careful. Try to keep the antenna away from noisy devices like motors and especially fluorescent lights. If you have pieces of metal that rub together in the wind, try to clamp them down otherwise they will generate noise. You will notice on the back of your radio there are three screw lugs for the antenna system. When using an untuned long wire antenna, only the A1 lug should be used and that little jumper tab should connect A2 to the GND lug. The A2 lug should only be used with a tuned and balanced antenna system that is beyond the scope of most users.
I would suggest that you not try to connect the GND or the A2 lugs to an actual ground as you may introduce some serious noise and hum that way. Anyway, the wonderful thing about these old radios is the opportunity to experiment around and find out what works best for you with what you have. There are three main reasons my EC-1b radio is emotionally important to me: first, because it began its life in the very month I was born and is thus the same age as I am, but more importantly, it was 1958 and I was only 13 when I found the main chassis of this radio in a junk pile at the Hancock Flying Field and I am proud that I was able to restore it after 50 years of laying in my garage.
Finally, this radio once belonged to Captain Hancock and was part of his now forgotten, but once very important flying field. This radio does a fine job of picking up shortwave AM, SSB and CW broadcasts as well as the old AM radio band. I was expecting this radio to have slightly more electrical noise than my S-38b with its isolated return bus, but actually it is just as quiet with its chassis connected to AC Neutral. This is a very fun radio to play with and doubly so knowing that it once belonged to Captain G. Allan Hancock and was once part of his flight operations there at Hancock Field. If you have a EC-1 or S38 series radio or if you decide to get one, I encourage you to fix it up or get it fixed up by somebody who knows radios.
They aren't difficult to work on, they perform splendidly, but heed my warnings or your survivors will be sorry. Drop me a line at if you have any questions or suggestions regarding these radios.
If you have any detailed comments, questions, complaints or suggestions, I would be grateful if you would please If you like my stories, tell your friends, if you don't like my stories, tell me. If you enjoyed this article about my EC-1b and want to read more regarding this line of radios, perhaps you'd like to read about or maybe you would like to read about one in the line of Hallicrafters radios that replaced the EC-1s or maybe you'd like to read about the very popular radio that heralded the sad end of the Hallicrafters company. I have written a little essay you might like that explains some of the principles of.