The Mississippi Historical Radio and Broadcasting Society
News Letter
Our regular club meeting was held on November 13. Our next meeting will be December 11, at 3:00PM at 2412 C Street, Meridian.
Your editor has been extremely busy and has not been able to get a newsletter out since August - and for that I'm sorry. I have tried to get some of the club members to put some articles together, but everyone is so sure that their stuff would be "dumb" and they don't want to embarrass themselves - as if the stuff I crank out is any better! Anyway quality or not, this issue is quite a bit longer than usual to try and make up for the missed issues.
Today is, of course, the 53rd anniversary of the attack on Pearl Harbor. Actually, Pearl Harbor was only one of three specific targets of the attack, the others being Scofield Barracks and the nearby air base. Our main article will give some details about the Radar that saw them coming -- as well as noting how our hobby of radio collecting also involves preserving history and heritage...
Also December is the end of the year - and there are no "shows" scheduled through the remainder of 1994. 1995, however starts off fast and furious. First is Houston Vintage Radio Assoc.'s Mega Auction on January 20 and 21. Also on the 21st, is the Arizona Antique Radio Club's Radio Roundup. Ohio's Society For Preservation of Antique Radio Knowledge (SPARK) is holding a winter Swap Meet on January 28, 1995 in Columbus. The Greater Boston Antique Radio Collectors club is holding their "RADIO XXVI" on February 26 in Westford, MA. Which brings us to March 18 - the tentative date for MHR&BS's fourth Annual Show, Swap Meet, Auction, & Museum. The date will be cast in concrete at Sunday's meeting -- So it's important everyone get their input IN! The weekend following our show (if the 18th is THE date) brings the AWA's Spring Meet in Charlotte, NC (March 24 - 25).
Another factor in the "New Year" is the postage rate increase. This means that the postage required to mail a members newsletters goes from 3.48 a year to 3.84. Factor in the "other" postage (sample copies, exchange, etc.)and the average per member goes from 4.35 to 4.80 per month. With the other expenses we have (paper, FAX, building rent for the show, etc.) the executive committee has placed a suggestion that the annual dues be increased from $10.00 per year to $12.00. This would be effective for new members and renewing members starting April 1, 1995. This issue will be taken up during the Annual business meeting during our Annual Show in March. Be thinking about it.
Speaking of rate increases - The Antique Radio Classified is warning everyone that they will have a "several-dollar" subscription rate increase January 1. If you want to avoid that extra bit of change - get your subscription in before December 31st!
Radio Collecting Today
It was a balmy quiet Sunday an hour after Sunrise. Two sleepy Army specialists had just spent their Saturday night seated in bucket seats staring at an indicator tube with little lines of light scattering all over it. Their assignment for the night had been to familiarize themselves with the new SCR-270B Radio Detection And Ranging set. Learning how to use this huge beast was hard enough during daylight - and extremely difficult at night. The brass thought that if anyone were foolish enough to attack Hawaii, surely they would be smart enough to do it under the cover of darkness - so these nightly training exercises had begun. Their orders were to secure at 0700 hours, and wait for a transportation truck to take them to breakfast - then on to bed. Since the truck was late, one of the technicians decided to "play" with the unit a little longer. Then it happened. All during the night, just little flecks of light would dance around the display in random patterns - echos of noise. But now the echo patterns were strong and consistent and there were dozens of them! At first, he thought the unit was malfunctioning - there just couldn't be that many planes coming in - not from that direction - and certainly not that many! He called his colleague, and they both quickly ascertained that it was no malfunction. They called into headquarters to report what they were detecting. The watch had already been relieved, and no one on duty knew quite what to do. At first they thought it was an incoming flight of bombers being brought in from state-side that was due that morning - maybe they had gotten off course a bit. No - there are just too many and they are coming too fast to be bombers! Suddenly the sky was full of enemy planes - and the rest -- as they say-- is history. Even if they had realized the situation right away -- in the 30 - 35 short minutes it took the attack force to reach their targets, little could have been done to have effected the outcome. The attack was well planned and very well executed. The Japanese pilots had trained for months flying practice run on a target range that had been setup to exactly mimic Pearl Harbor and the other targets. Remember - WE weren't at war!
How much did the President know before hand? Did he sacrifice American lives in allowing that attack to go un-challanged in order to ensure that the U.S. would enter the war? Did they under-estimate just how much damage the Japanese could inflict? The politics surrounding the attack on Pearl harbor will be argued for decades - But it is a sure thing that they knew the attack was not just possible but also likely. Billy Mitchell had predicted that if the U.S. continued to force Japan's hand (oil embargo) Japan would resort to retaliating and that the likely target was Hawaii. The presence of one of the first RADAR units is proof that someone took that threat seriously. The SCR-270B is a HF RADAR in that it's operating frequency is relatively low. This made both its effective range and accuracy quite limited. The unit was huge, usually mounted to a flat-bed trailer. The power generator and electrical equipment were placed on the ground beside the trailer. The transmitter, receiver, control electronics and operator positions were all part of the lower mast assembly, with the antenna array up top. The entire mast and antenna assembly (including the operators in their bucket seats) rotated 360 degrees. The elevation was fixed, usually aimed just above the horizon. The operators would swing the antenna in the direction they wanted to scan, watching for any echos to be displayed on their displays. The displays were similar to oscilloscope Cathode Ray tubes, and had a sweep that went from left to right going across the bottom of the screen. An echo would show up as a vertical "pip" at some point across the screen. The further to the right, the further away the target was. A larger "pip", usually indicates a larger target, or one that returns a very strong echo. A group of aircraft would show as a "clump" of "pips". That Sunday morning the scope must have looked like a forest... moving towards them like a runaway freight train! RADAR works by sending out a pulse of radio energy, then "listening" for an echo to return. An object reflects some of the radio pulse back toward it's source, allowing the same antenna that transmitted the pulse to receive an echo back. An echo means there is something out there. How large the echo is tells us (generally speaking) how big the object is; and how long the echo takes to get back to the antenna tells us how far away. There are several accepted units of measurement on distance in RADAR - a mile is 5280 feet or 1760 yards. a NAUTICAL mile is defined 6076 feet or 2025.3 yards. To make things easy a RADAR mile is defined as 2000 yards or 6000 feet. When ranging that introduces about a 1% error from a nautical mile. When distances are short, and more accuracy is needed, yards are the unit of measurement. Two useful formulae for calculating distance:
Mile = (delta)t/12.36
Yard = 164(delta)t
where (delta)t is the delay in microseconds.
If a scan across the scope took 500 microseconds, and a PIP showed up halfway across, you would know that the target was some 20.2 miles out (250 / 12.36 = 20.226).
In the case of the SCR-270B, the entire unit rotated to scan in a given direction -- the detected object was in the direction the antenna was pointing. As mentioned before, the SCR-270B used a relatively low frequency. The British invented a new tube using a super strong magnet to focus a pulse of electrons into tight resonant cavities formed into the plate. The physical size and shape of these cavities determine the overall resonant frequency of the tube. The British gave the Americans the magnetron to help in the war effort. Since the magnetron is basically the entire transmitter section of a RADAR (needing only a power supply, pulse forming and timing circuits) small and lightweight (comparatively speaking) RADARs could be developed. These new tubes also operated at much higher frequencies - 3000MHz to 10,000MHz allowing greater ranges and accuracy. A new type of transmission line was developed - waveguides. Because of the high frequencies involved -- and the increasing prominence of Skin Effect at those frequencies -- waveguides became practical and economical way to move the now very large power output of modern Magnetrons (approaching 100 million watts peak!!!!). Also, choke joints (a waveguide that rotates) came along which allowed the antenna to rotate, while everything else stayed put. A servo system was developed to indicate what direction the antenna was pointing at all times, resulting in the development of the PPI type display. PPI stands for Plan Position Indicator. The difference here is that the display still sweeps to indicate distance, but now it starts at the center (to indicate where you are) and sweeps to the outer edge. The servo system rotates the yoke so that the sweep runs from the center out in the same direction as the antenna is pointing. So when an echo does occur, it shows up on the screen relative to your position in both distance and direction. This form of RADAR is still the primary RADAR in use today - but as often as not looking at airliners, ships at sea and even weather. The newest RADAR has one added twist. If an object is moving toward or away from an observer, any emission (even a RADAR echo) is shifted in frequency equal to the relative speed (up for approaching - down for moving away). This effect is known as the Doppler effect - most everyone has experienced this at one time or another - like when a train passes - the whistle drops in pitch noticeable just as the engine passes. Measuring this Doppler "shift" tells you how fast something is approaching (or departing). The common uses for this are speed RADAR (police and sports, etc.) and very recently Weather RADAR.
Most historians credit RADAR as the factor that tipped the balance in favor of the Allies in the Battle of Britain. Had America been at war (with the attendant preparations and alert status) the early warning provided by the RADAR crew on that Sunday morning 53 years ago might have made the outcome of the Japanese attack on Pearl Harbor very different.
Since RADAR sets like the SCR-268 & SCR-270B were so large, few have survived I don't know of any on display though there is bound to be one somewhere. Few radios have ever been so directly tied to a single event as the SCR-270B RADAR set -- forever known as the set that saw them coming!
I hope the lessons learned on December 7, 1941 won't be lost on our younger generations. I have a cousin who is buried in a tomb of cold steel under a white memorial just off of Ford Island in the center of Pearl Harbor... Stepping aboard that memorial and peering into the waters' depth at what remains of the USS Arizona reminds us that freedom isn't free - and every so often some must pay the ultimate price for the rest of us.
Book Reviews:
Several new books have hit the shelves recently -- The Collectors Guide to Antique Radios: Third Edition (Bunis & Bunis); and -- Transistor Radios - a collector's encyclopedia and price guide (Lane & Lane).
The Third Edition of the well respected Bunis book lives right up to what we all have come to expect: Excellent. Prices are, of course, debatable (though that is expected in this hobby!). Absolutely on the MUST HAVE list! $18.95 Soft Cover.
Transistor Radios: A collector's Encyclopedia and price guide. This book is by a father and son team who obviously love their radios! The coverage is excellent - the only weak area is in large multi-banders such as the Zenith Trans-Oceanics and GE World Monitors or the like. Their listing of novelty radios is one of the largest we've seen anywhere. Prices - VERY realistic! Another on the MUST HAVE list! $19.95 Soft Cover
Book Announcement:
The Zenith Trans-Oceanic:
The Royalty of Radios by John H. Bryant and Harold Cones
Pre-publication offer for $23.95 for a signed & numbered copy. After December 15th the price goes to $24.95 + $2.00 shipping & handling. Said to contain the most detailed and well illustrated documentation of the 40+ year history of the Zenith Trans-Oceanic. Order directly from:
The Radio Professors
P.O. Box 592
Stillwater, OK 74076
Make checks payable to "The Radio Professors."
© 1994, The Mississippi Historical Radio and Broadcasting Society.
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