Jackson Research, LTD

IntelligentMagnetics™ Bell&Howell Datatape

Industrial/Aerospace/Military Specifications

Designs by the inventor of the Slotless Wide Airgap Motor


The Data Evaluation Lab (DEL) at the Goddard Space Flight Center is the only known place that has the equipment and expertise to playback the 1" wide magnetic tapes and to recover data.

Jackson Research has the original blue prints (literally) for these capstan motors for the MARS tape recorder (M-22). The MARS recorder was much smaller than the 3700B, but used the same magnetic technologies. The motor in the photo is from a limited production facility in the basement operated by John Jackson and two others. The shaft is ground from sintered Tungsten. The optical recorder used a light image pipe to double the line count for a 10k lines per revolution tachometer built into the rear of the assembly.

Silver was sputtered onto precision cut optical grade glass disks. The high line counts were photo etched from very large photo masks which were optically reduced to minimize mask errors.

The tape recorder capstan motors were high performance Alnico magnet torque motors in precision machined housings with integrated optical encoders. The bearings were typically grade 9. These motors were controlled in closed PLL loops designed by Eugene Cooper and Henry Martiya.

IRIG 28 track assemblies had seperate record and read interlaced head assemblies resulting in four heads per assembly. The cores were hot pressed ferrite with sendust tips. The highest record frequency was around 1.5 MHz with 20dB S/N ratio. These high definition 28 track one inch head assemblies were used in airports to rrecord all flight date in the control towers. Also, the marines were using it in intelligence gathering. Several of the manufacturing phases had been improved with the last one fine grinding after alignment of the gap depth in a specially built tool fixture using 15 microinch glass gap head assemblies in a linear - as opposed to the Ampex quad heads - video recorder. Also, initial layout of solid state head assemblies and sputtering of sendust on quartz substrates were made. No problem with alignment here and 100 channels per inch were easily achievable. The economy got into a slow down and B&H closed the lab.

These read/write heads were given to Jackson Research by Al Bakowski, Bell&Howell's magnetic head specialist.

The Apollo 11 Lost Tapes

Bell&Howell Datatape Sale to Kodak

The bulk 14 inch reel tape eraser was used extensively. The Lost Apollo tapes fell victim to this device. At one point, the US Navy had a problem with spurious spectral signatures left on the tape by the eraser. It was interfering with sonar signature ananlysis. The problem was determined to be a transient current surge in the erase coils at turn on. The problem was resolved by slow turn on as was accomplished in SMPS 10 years later.

Tape transports moved 1" wide tape across 28 channel heads with capstan motors controlled by 2nd order wide band PLL loops (position control rather than velocity control). These motion analyzers were the first flutter meters. Closed loop PID motor controls cannot compete with this technology.

For you digital recorder owners who are snickering to yourselves that you are so clever to avoid all of these problems by investing in digital machines, think again! Although the digital playback electronics contain a digital time base corrector to minimize the effects of flutter, the digital tape transport still suffers from all of the above shortcomings. In fact, the problems may be even worse due to the short wavelengths and narrow tracks required for high density digital data. When the flutter on the digital machine exceeds the correction range of either the data detector or the time base corrector, the result will not be easily recognized flutter, but rather data errors which may well drive the recorder into hysteria. How do you test the transport for flutter due to worn parts? One way is to use an analog cue track on the digital deck to test just the transport. This technique has been applied to several digital recorders, including the ubiquitous ADAT.