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Cold War QRP: A Case of "Discone Fever"?

04/23/2008

Introduction

The control room was a scene of choreographed chaos. Lamps flashed, switches were thrown, checklists were consulted and authentication codes were confirmed. As the second hand on the wall clock inched forward, the operators, each at their respective stations, turned a key.

A Titan II missile, perched within the adjacent silo, stirred as batteries were energized and relays closed. Inside, pumps and a maze of tubing sprang to life, bringing hydrazine and nitrogen tetroxide into contact. The chemicals spontaneously ignited, a thunderous roar filled the air and angry clouds of exhaust and steam jetted from the open silo as though from the mouth of a volcano. The missile, serial number 98-31772-5B rose, slowly at first, and then rapidly gained speed, ascending until it had diminished to a point of light high in the sky. Minutes later, the missile descended, delivering its 9 megaton nuclear warhead to a hardened target somewhere in the Soviet Union.

Or so it might have been. Luckily, for the sake of all of humanity, cooler heads have prevailed, so the scenario above never actually played out. In fact, in the early 1980s, President Ronald Reagan ordered the deactivation of the 54 operational Titan missile sites. Eventually, the missiles were removed and all of the silos were dismantled and destroyed -- except for one.

The Titan Missile Museum

Base 571-7, located about 12 miles south of Tucson, Arizona, has become a National Historic Landmark. Now operated by the nonprofit Arizona Aerospace Foundation, the site has been reborn as the Titan Missile Museum. There, for the price of a ticket, one can step back into time and experience the front line of the cold war in a very tangible and personal way.

Above ground, there are some interesting exhibits, including various support vehicles, a helicopter and several examples of rocket engines. One can also examine the 700 ton reinforced concrete silo lid -- now permanently cast in a half-open position.

A Man-made Cavern

Below ground, one can traverse tunnels and various chambers including the command and control room. Huge steel springs suspend these compartments from the surrounding rock, allowing them to shake and rattle in the event that the site itself became the target of an enemy attack. In the control room, the launch electronics are still functional. The tail of a punched paper tape dangles casually from its spool in a rack-mounted tape reader. That tape still contains targeting information. It holds the secret as to where the warhead would have landed and who among our enemies would have suffered complete annihilation.

Nearby is the launch silo, and within it, a Titan II missile. This particular rocket is a training vehicle and has never actually been fueled -- a good thing as the propellants are both highly toxic and corrosive. Just the same, access holes have been cut into the missile to verify that it is no longer in launch-capable condition. Needless to say, the reentry vehicle at the top of the rocket is empty. There is no warhead to worry about.

Discone Fever

A visit to the Titan Missile Museum is a worthwhile trip for anyone with an interest in rockets, science or history. Most of the hams I know fall into one or more of these categories. Yet, there is an additional attraction to anyone interested in radio, in particular those with a valid ham license.

In the early 1960s, as part of the installation of the Base 571-7, the Collins Radio Company erected an absolutely beautiful discone antenna at the missile site. Discones are broadband antennas -- they are capable of radiating signals over a wide range of frequencies. The lowest usable frequency on a discone is established by the physical dimensions of the antenna. This particular antenna is something on the order of 80 feet tall, with an enormous crown, which means it will radiate effectively over a large portion of the HF spectrum.

The Infection

In prior years, I had toured and enjoyed the Titan Missile Museum at least twice. It was only recently, however, that I learned that the general public can sign up for, and request the use of this antenna. The Green Valley Amateur Radio Club (GVARC) has a Web page with comments about the discone and directions for requesting its use. I decided that this was something I had to tinker with. You might say that I had contracted a case of, well, "discone fever."

Cold War QRP

For this adventure, I brought along my Yaesu FT-817. The 817 is a fine multi-mode 5 W transceiver that works well either from an internal battery pack or external power. I opted to run the rig from a cigarette lighter jack in my vehicle. The Yaesu is a fairly expensive piece of equipment, so to avoid blowing it up in a moment of confusion, I built a gizmo I call the "Oh-Shoot!" box. (As you may well imagine, the name was inspired by a more descriptive phrase, which is not, however, suitable for use in good company.) The "Oh-shoot" allows me to connect an external power source to my FT-817. The Oh-shoot is fused, both high-side and ground, has reverse polarity protection and an overvoltage crowbar. It also has a set of diagnostic LEDs that allow me to verify proper voltage and polarity before the on-switch is thrown.

With my 817, I normally carry an LDG-Z100 tuner. GVARCs Web page says that the discone will tune from 6 to 30 MHz with an SWR less than 2:1, but I figured the tuner would be nice to trim things up as needed. I have used the Z100 and FT-817 to drive every conceivable makeshift antenna and I've found that I can match to just about anything but a wet noodle.

I enjoy operating CW, but I thought some PSK31 might be fun, too. Thus, I brought my laptop and a Signalink SL1+ PSK interface.

The museum's discone is erected behind a security fence, so you can't actually walk up to it and touch it. Electrical access is provided by a UHF connector housed inside a metal junction box just to the south of the antenna. As it turns out, someone was courteous enough to include a length of coax to link the box to my radio gear. I was prepared, however. I brought and used my own cable.

Securing permission to use the antenna is easy. I walked into the museum and asked to use it. I showed my driver's license, a copy of my ham license and I was asked to sign a guest log. That's it.

Hooking Up

I backed my vehicle up to the junction box, opened my tailgate, hooked up my equipment and set up a lawn chair. I began working stations around 1932 UTC and finished about 4 hours later. Some of the contacts I made were CW, some were PSK31. In some cases I lost folks in fading or noise, in some cases they lost me. Nonetheless, I was astounded at how far my tiny signal projected.

From my position in southern Arizona, on the 20 meter band using low power CW, I exchanged information with operators in New York, Pennsylvania, Florida and Texas. I tried the 40 meter band and was able to contact California. Using low power PSK31 on the 20 meter band, I reached out and "touched" Massachusetts, California, Washington, Oregon, South Carolina and Kansas. I would love the opportunity to run this antenna at night, or in the future when the solar cycle has progressed and band conditions have improved.

I am very grateful for having had the opportunity to work with this antenna and experience, on a firsthand basis, one small aspect of our cold war history. I would urge all of my fellow hams to share in this experience. You can find more information about the Titan missiles at Wikipedia and through SiloWorld.

Pete Friedrichs, AC7ZL, has held a lifelong interest in science, electronics and radio. He holds a BS in electrical engineering, has authored two books, including Instruments of Amplification, available from the ARRL bookstore. He received his ham license in 2003 and derives pleasure from working CW and PSK31, particularly QRP. When he's not at work or tinkering with electronics, he enjoys hiking, writing and playing guitar. He can be reached through his Web site: www.hpfriedrichs.com/.

H. P. Pete Friedrichs, AC7ZL



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