There is also a gallery of photographs from Operation Red Line - click here.

In February of 2008, Chris (VK3AML) and Clint (KA7OEI) visited Bob and completed a two-way optical contact across Yucca Valley - read about that contact here.

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From Bob Legg's Narrative:

How it came about:

"The company that we worked for, Electro-Optical Systems in Pasadena, California, had a number of amateur radio operators (or 'hams') in the company and the thought among some of us was that we should have an amateur radio club among our employees.  We had our first get-together to discuss the possibility of forming a club in late January of '63 and the question brought up at the time was 'Why have a club within the company when almost all of us have membership in one or more amateur radio clubs outside the company?'  The consensus was that if we were to form a club within the company, why not have some kind of a goal, the breaking some kind of a record or, as Jack Pattison later wrote '...contribute something scientifically new to the field of electronics.^'1

Figure 1:
Three of the participants of "Operation Red Line"
From left to right:  Robert Legg - in charge of  the receive site.  Duane Erway - in charge of laser construction.  Jack Pattison - in charge of the transmitter site.
Click on the image for a larger version.

"We went away from that meeting thinking about this and when we met a week later we had come up with a few ideas of what we might want to do:  It was decided 'Let's build a laser and see if we can't break the world's record.'  This record wasn't very far at the time, about 35 miles I believe, established by Hughes Aircraft.  We finished the meeting having chosen some members to head up various tasks that were involved, such as laser construction, receiver construction, path selection, someone to be in charge of the receiver site and laser site, and someone to be in charge of material acquisition.  Those people weren't very hard to choose as all but two of those who showed up at the meeting participated in the laser event, and amongst those who participated were:

Dr. Henry Richter, W6VZA - Project manager
Duane Erway, ex W6KAQ - Project coordinator and laser construction leader
Dave McGee, K6GPJ - Site selection leader
Jack Pattison, W6POP - Transmitter site leader
Bob Legg, W6QYY - Receiver site leader
Parks Squyres, ex WA6AKM, now W7PKS - He owned the telescope and built the photomultiplier assembly

Others involved were:

Chuck Cunningham, K6YTP
Bob Fuller, W6KHK
Ron Sharpless, ex WA6LMV, now N7ERC
Verne Gallinger, K6VJJ
Ross Joe, K6CPB
Ed Reed, K6IGC
Darrel Wilcox, ex WA6THK - He ground and coated the mirrors for the laser in the EOS optical shop.

Also involved were a number of non-hams:

Dr. Joe Nuestein - The head of EOS
Jack Miller - Excellent mechanical engineer
Dick Stultz - Material acquisition
Steve Fine
Chet Campbell
Jay Snell
I believe that there were two members that didn't participate in the actual event:  One of them may have been Manny Weinberg, K6HWM.

Shirley Pattison, K6DPX, helped as well.  Although not a member, she provided a radio relay between Grassy Hollow and the telephone.

Figure 2:
Top:  The laser assembly in the lab with the laser tube, spotting scope, confocal mirrors and collimator mounted in the steel channel.  Visible in the background on the right is the Viking II transmitter (used as the exciter) while the neutral-density filter may be seen at the end of the channel.
Bottom:  The laser transmitter, in the tent at Grassy Hollow being adjusted.
Click on either image for a larger version.

About laser construction:

"We were able to obtain a Helium-Neon tube, already fitted with Brewster windows on the ends used to maintain polarization.  We were originally thinking of modulation the laser using a Kerr cell, which rotates polarization, but this idea was later abandoned due to the awkwardness and hazard of using a Kerr cell - which often contains nitrobenzene, a very hazardous substance - and the fact that the exciter itself could be modulated.  We also obtained two mirror mounts with micrometer adjustments for alignment, and we installed confocal reflectors.

"The exciter and modulator was a Viking II made by Johnson - a very popular line of ham equipment at that time in the country:  I had a Viking II, so I offered its use.  We excited the laser at 28.62 MHz - in the 10 meter amateur band - and by amplitude-modulating the Viking, which put out about 100 watts of RF, we were able to excite the laser.  We collimated the laser with a 10-power telescope with a 2-inch exit diameter and we mounted the whole assembly,  including a spotting scope, in a steel beam that was 12-inches wide, 4-inches deep, and 6-feet long.  The most power we ever got out of the laser was 125 micro watts.  The laser tube itself had no internal electrodes, requiring external RF excitation:  Initially, we had no idea how to do this, but after some experimentation we determined that applying RF to strips of foil properly placed on the outside of the tube did the job.


A sense of urgency:

"I'm sure that we could have improved the output power with more experimenting, but there was an overwhelming urge to get out into the field as fast as we could because we were aware that there were at least two other groups that were about to break the current record, one being Ryan Aircraft in San Diego, California [Ryan Aircraft was the company that built the Spirit of St. Louis - Charles Lindbergh's airplane] and another being the Army Signal Corps that was setting up a facility to break the record - and while they were out there pouring concrete for foundations, we were rushing this thing out into the field instead of having it sit on a workbench.

The receiver:

"Parks' Newtonian telescope had its own mount and used a 12.5 inch mirror.  For detection we had available an S-20 photomultiplier tube and a power supply for it:  This was probably not the best choice of photomultiplier tubes, but it seemed to work and we had it available - that's to say, free.  We also had an audio amplifier with a speaker - plus a tape recorder to document the event.

Testing:

"The first tests were performed at EOS once the laser was up-and-running.  Our building, which was only a few months old, was about 300 feet long and we beamed our laser down the hall at night:  With a mirror at three corners, the beam went around the building - from the south hallway, to the north hallway, to a separate room for the receiver.  With neutral-density filters that we'd hoped were equivalent to the path loss, we were able to get very good communications:  What we didn't have were the scintillation effects which about wiped us out!

Transmit and receive sites:

"The sites that we used were determined by Dave McGee and his team:  They'd studied topographical maps for some time and field-checked accessibility of the two sites that had been selected to meet our goal of 100 miles or so.  The transmitter site was easy to get to with paved roads all of the way, to the Grassy Hollow campground in the San Gabriel mountains at about 7300 feet.

"The receiver site, however, was something else:  One of the selected locations was in the Panamint mountains - but how one was to get up there was a problem. so they went out to investigate, to see if there was an old mining road to get to the top.  The first stop was the (almost) ghost town of Ballarat - a town with one resident, well-known for his prospecting over many-many years.  He was an old, old gentleman who went by then name of 'Seldom-seen Slim' and very few people ever got a chance to meet him.

"Dave McGee and his team drove into Ballarat and ran across Seldom-seen Slim and got his cooperation - something that we later found was unusual because he avoided people and didn't like to talk - but he was of great help and told the team how to get up at least partway via a mining road, at the end of which was an old mining operation that was closed down.  At this old mining operation was a guard to keep people out, but if permission could be obtained to cross this locked facility another, older, road went to the top.  Dave and his team went up the road, met the caretaker at the mine and talked him into letting them pass through, onto the old road.

"It took quite a bit of time to fill in ruts that had washed out parts of the road, but they eventually got very near the top - an elevation of about 7400 feet with a good view toward Grassy Hollow.

Figure 3:
Top:  At the receive site, the telescope in the tent (left) and the large flash lamp that was to be used to allow sighting-in of the receive site (right)
Middle:  Front view of the telescope.  The photomultiplier housing may be seen, strapped to the telescope at the top of the picture and the spotting scope may be seen below the telescope.
Bottom:  Rear view of the telescope, looking out of the tent.   Below the telescope, on the table, may be seen a xenon flashlamp, the power supply for the photomultiplier tube, and the audio amplifier.  In the background can be see the flashlamp that had been tried for sighting-in the receiver site.
Click on an image for a larger version.

The expedition:

"We eventually thought that we were ready to set up camp and try this - but that was probably a mistake as we should have spent at least another two weeks polishing off problems that became very obvious to us once we were on the site.

"My team - the operators at the receiving site - arrived at 3:15PM on Friday, thanks to the owner of our company who gave us a day off, giving us a long weekend.  I, in my Plymouth Valiant (my wife's car, actually,) was unable to make the last 500 feet of the very steep road so Ron had to drag me this last distance:  To her dying day, my wife never knew where I had taken it!  By 3:30 we'd established the 6 and 2-meter radio links used to communicate between the two sites, pitched our tent and set up the telescope. 

Finding the sites in the distance:

"I'd brought along a huge flashlamp that was mounted inside a WWII signal lamp - one of the types in which you move a handle on the side to send code:  The shutter had been removed and a very large xenon flash lamp had been installed and there was a huge power supply to run it.  With that [flash lamp] we thought that we could aim it towards Grassy Hollow and the transmitter team would be able to beam the laser toward us.  When it finally got dark we were able to sight-in Parks' telescope with the help of the headlights from W6KHK's [Bob Fuller's] car at the transmitter site.

"For aiming the laser, the flash lamp didn't cut it - presumably because much of the optical power was in the blue spectrum which was absorbed by the atmosphere, but everyone else in southern California must have seen it!  Fortunately, we had contacted the FAA and told them that we were going to be flashing this light, so they were able to pacify all of the pilots flying in southern California, and there was no problem.

"Failing with the flash lamp, we still had an ace-in-the-hole:  A 5-million candlepower aircraft flare that we'd managed to obtain through the military.  We unpacked the flare and ignited it on the ground and, for a few seconds, the transmitting site was able to see this and know exactly where to beam the laser.  Unfortunately, the wind was blowing in such a direction that the smoke from the flare went toward the transmitting site, obscuring the flare itself, and they got only a few seconds of visibility - but it did light up all of the terrain around us - such as the town of Trona to the west and Death Valley to the east - and many people must have wondered what-on-Earth was going on atop the Panamint mountains!

Aiming the Laser:

"Once we were ready to operate, they turned the laser on and attempted to beam it toward us - something that turned out to be a rather large problem:  Someone in the group had calculated that moving one end of the laser assembly just one-hundredth of an inch would move the beam 175 feet at the receiver site and, as it turned out, the 'scanning' technique used at the transmitter site certainly needed some improvement.

"I was unaware that no attention had been paid to the fact that we needed some kind of micrometer-type of adjustment on the beam and it took a half-hour of awkward 'scanning' of the laser before we were able to see it at the receiver site.  I asked Jack Pattison, who was at the transmitting site, what the problem was with moving it:  We would see a flash and it would disappear, so we'd try to get them to back up - but in the process of backing up they would go too far and it would be lost for another 10 minutes or so.  Jack informed me that the only adjustment that they had was to tap the end of the steel channel in which the laser was mounted with a rock.  When they got close - that is, when those at the receive site could see it once in a while - they switched to the 'fine adjustment' tool, which was a smaller rock!  I think that that could have been improved considerably!  Once we got beamed in (at about 10:55 PM) we were quite aware that there were a lot of atmospheric conditions affecting the path and that the beam was fluctuating very rapidly - but that's scintillation for you!

Communications - at last:

"We did make some communications by laser on Friday night - but they were not too successful, although we could understand it occasionally with signals peaking Q3, but later dropping off.  We rescheduled to come back up at 4 AM - well before sunrise - hoping that the scintillation would be less with a more-stable atmosphere.

"During the night, some winds came up and it took two men to hold the center post of the tent at the receiving site with the other four trying to get some sleep - but that was difficult since the telescope and electronics took up the middle of the tent causing everyone to lay up against the tent sides - with the wind blowing and tent flapping up against our backs, keeping us awake.  Later that night, the winds increased and the tent came down:  Murphy was working overtime!

"At 4 AM, we had no winds and were back up and ready to run, but Murphy's law struck again as they couldn't get the laser to work.  By Saturday night things were up and running again at about 9:30 PM with a better laser signal than the night before and for about an hour-and-a-half, we recorded what we thought were fairly-good communications (Q4-Q5 at times) - considering that we had 1/8th of a milliwatt of power from the laser over a path of (over) 118 miles.

"Again, we decided that things might be better in the morning so a schedule was set for 4:30 AM on Sunday.  This time, the receive site was again up and ready to go, but no-one was awake at the laser site - Murphy strikes again!

Some comments about the audio recordings:

"The first thing that you'll notice on the laser communications tape is a great deal of noise in the higher portion of the audio spectrum and we generally played that back with the higher frequencies rolled off.  I've had thoughts about why all that noise was there, but there was nothing that we could to about it at the receiving site.  I think that a lot of the noise was due to the resistor that was between the high-voltage power supply and the photomultiplier tube - which was 100k - and it probably was a carbon [composition] resistor and that probably contributed a lot of noise - at least that's my theory at this time.  It probably would have been much better with a metal-film resistor, which at that time was available - probably for a couple of years before that - and this might have reduced the noise quite a bit."

[End of Bob Legg's narrative]

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Comments:

As it turned out, the EOS group's success became fairly well-known with brief accounts having appeared in several industry trade magazines as well as brief mentions in amateur radio magazines and local press at the time.  Bob has said on several occasions that they were sure that their record would soon be broken - but this turned out not to be the case:  After news of their success, it seemed that the other contemporary distance attempts were simply abandoned.  Bob has expressed some surprise that this record hadn't been broken - or even reported to have been nearly duplicated - for several decades after the 1963 experiment - even long after technology had advanced to the point where lasers and the associated electronics were readily available on the surplus market and had become portable enough to be practically transported by a single person.

Considering how new laser technology was in 1963, I find it amazing that a self-motivated group dedicated the effort, time, money, and persistence to pull it off.

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Audio clips:


The following are some excerpts from the original log tape recorded at the receive site:

• Early reception:  On the evening of May 3 they were still trying to peak the beam and work a few minor bugs out of the system.  In this recording, made at about 11:50 PM, you can hear some of the goings-on at the receive site - including radio communications between the receive and transmit sites - and some of the early signals from the transmitter site before conditions deteriorated.  Also in this recording you hear Jack, W6POP, mention (via the laser link) that, on May 2, they'd measured the Laser's output power as being 125 micro watts.  Portions of this recording have been adjusted to compensate for differing audio levels.
  

• Description of transmission:  A prepared statement was read multiple times for the log tape describing the experiment and the equipment used.  This recording is of Jack, W6POP, himself and scintillation (fading) is clearly evident.  A version of this with applied noise reduction may be found here:

        Transcription of the above audio clip:
Coordinates of the two sites:

These coordinates are based on information provided by Bob Legg and Dave McGee and are based on WGS84 datum.

Transmitter site - A location north and west of the Grassy Hollow Campground in the San Gabriel Mountains:


Receive site - Above and east of an area called "Middle Park" and along a road that somewhat follows an NNE-SSW ridge:


Calculated distance between the transmit and receive sites:  119.145 miles (191.74 km)

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Article references:

Two of the publications in which this effort was reported include:

• Electronic Design News (EDN):  November, 1963
• ¹QST, July 1963, pg 68.
  

Other technical references:

• Burle Photomultiplier Handbook - A good technical reference about the theory, operation, and specifications of photomultiplier tubes.   An "S-20"  photomultiplier tube is a type that  has somewhat better "red" sensitivity than most standard photomultipliers, which typically have good sensitivity only in the blue/ultraviolet end of the light spectrum.

Acknowledgments:

I would like to thank Bob Legg for his invaluable assistance in providing specific details of this event.  I would also like to thank Dave McGee and those others that assisted Robert in his gathering of materials and researching of data.  Of course, we wish to thank all those who were involved with this project those many years ago who had the motivation, ambition, and foresight to undertake a project that was, at the time, at the leading edge of technology and would still involve quite a bit of effort to replicate even today.

Comments, corrections, or questions?  Send an email.

In February of 2008, Chris (VK3AML) and Clint (KA7OEI) visited Bob and completed a two-way optical contact across Yucca Valley - read about that contact here.

Go to the Operation Redline Picture Gallery page or Go back to the "Modulated Light" page.