The Dynalyzer Family

A History of the Dynalyzer Evolution

by Dr. Jonathan S. Shapiro

Greenwich Instrument Co. Inc.

The Dynalyzer was conceived at Machlett Laboratories in Stamford Connecticut in the early 1970’s. The first version of this product was the Y-1 Dynalyzer, designed by Bill Holland and Andy Cunningham.  It was a square steel container filled with Sf6 gas at atmospheric pressure.  Inside was a moving coil  DC milliampere meter with three ranges, a ballistic MAS meter, and AC filament current meter, and a voltage divider. There were windows in the top of the box to see the meters which were connected in series with the high voltage wiring in the anode and cathode. The meters were electro-statically shielded, and the ranges were selected with a long insulated shaft. The first version of this unit did not have frequency compensated voltage dividers, but after the matter was called to our attention by NBS (NIST today), modifications were made on this unit by Dr. Jonathan Shapiro to produce a useful frequency response to 1 kHz, which for single and three phase generators of the time was adequate. The modified units were called the Y1-A Dynalyzer, and were approximately  20 inches cube, and weighed 75 pounds.

Approximately 100 Y1-A dynalyzers were built from 1974 to 1975. (Sorry no picture available.) The unit had several drawbacks. One was its bulk. It was difficult for one person to carry. One had to peer  between the HV cables to see the meters. It was useful for setting up x-ray tube emission on the generators of its day. It was also used in the Machlett factory on the x-ray tube line. As it had no active electronic components, it was immune to high voltage surges.  The last time we at GiCi calibrated one was in 1990! Please, do not try to sell or give me one!

As the digital age advanced, Machlett wanted a leading edge product for compliance testing. There were several abortive attempts to subcontract a digital dynalyzer, but these came to naught. Some were fairly massive, including a relay rack size device with 6 digital panel meters, and a control board with 100 IC’s. The high voltage tank looked like an underwater mine, being a pressurized spherical unit weighing close to 100 pounds!

The engineering team under Dr. Jonathan Shapiro was Tony Pelligrino (who later founded Lorad), Vincent Berlutti and Tom Fitzsimmons. Tony was an expert in high voltage, as the design engineer for Machlett’s image intensifier power supplies, Vince was just out of the Army, but was an excellent midnight circuit designer. Tom was our third engineer.

Jon designed the optical milliampere sensor on his ding room table at home and Tony designed the voltage divider structure. Vince would go home at night and come back the next day with a large page of digital TTL logic schematics for the digital display. It was amazing that it all worked so well.  As the project grew, and was properly funded, it began to consume the drafting department. One designer/draftsman did a layout of the Dynalyzer II  high voltage tank at 5 x scale, and was sprawled out over his drawing for hours at a time. Contract draftsmen and women were brought in for PC board design. Eventually it all came together, recycling as many parts as possible out of Machlett’s tube parts bin. Ever wonder the Dynalyzer tank looks like an X-Ray tube?  It was originally built out of overstock aluminum  tubing, and  when that ran out, we had to scramble to find an alternate. No one thought more than fifty of these would ever be built. Well over 2500 units must have been built since 1975!

The Dynalyzer II went into production in 1975. The MOSTEK calculator chip that was designed into the display unit to calculate mA= MAS/time  was already out of production.  Jon scrounged various distributors, and ultimately bought the remaining stock that was in a engineers desk at MOSTEK.  An early high voltage unit blew up quickly and a failure analysis by Henry Woerz in QA found that the “741” IC’s were of various die lots and not consistent. We switched to the National LM 343H op amp, and reliability significantly improved.

Production went along until everyone realized  how obsolete and scarce the parts were becoming in the display.

Begin the Dynalyzer III.

1979 was the most chaotic year possible at Machlett. Raytheon Medical Systems was formed, and bought Amrad in Melrose Park. The Step One Step Two Gamma Camera was going into production, and the Dynalyzer III digital display was being designed.

Designing the Dynalyzer III HVU was no big deal. That was just a simple addition to the schematic, and a new PC board and front panel. The digital display was something new to our group.  Luther Foreman designed the Motorola 6802  CPU board,  front panel- display board, and Jon Shapiro designed the analog board. The power supply was a warmed over Dynalyzer II power supply board. Vangalla Reddy wrote the code and massaged it to fit into the ROM. We tried to use as many common components as possible from our other projects.

With only one  update to the code after production started, the Display worked very well.

About 1983 the bean counters realized that the Dynalyzer was not going away, and did some cost reductions on the HVU to make the cast tank known as the Dynalyzer IIIA.

Some variants of the product exist. There were Dynalyzer II CT units, which had a DC hall effect filament current sensor. Dynalyzer III CT units were the same.

Shortly after Machlett  began to close up in 1988-89, Greenwich Instrument Co. Inc. was formed to service this equipment, benefiting from the knowledge of  Ben Wilson, formerly sales manager for test equipment at Machlett, and Jon Shapiro, engineering manager.

Varian purchased Machlett and moved the Dynalyzer to San Carlos CA. Soon, the supply of  Panasonic thermal printers came to an end. The part was discontinued. Varian designed an interface for the Telpar OEM impact printer, and that was the last change made to the digital display.

Varian tired of the product and sold it off the Fischer Imaging, who was also the main customer for the collimator. Fischer changed the main PC board of the high voltage unit.  Fischer made the “CT” option standard after a period.  After a year or two, Radcal bought the product line from Fischer, and has again redesigned the main PC board, leaving the “CT” option and renaming the high voltage unit, the Dynalyzer IIIU.

What the future portends for this product remains to be seen. It remains a unique product, and its only similar competition is the Inspec 200 system, which GiCi imports from Japan, and assisted in its design.

Table of Variations of the Dynalyzer High Voltage Unit


Dynalyzer HVU Model Manufacturer Milliamps Filament Tank
II Machlett 1 range AC Brazed
II CT Machlett 1 range AC/DC Brazed
III Machlett 2 ranges R-F AC Brazed



III CT Machlett 2 ranges R-F AC/DC Brazed
IIIA Machlett, Varian, Fischer 2 ranges R-F AC Cast
IIIA CT Machlett, Varian, Fischer(2) 2 ranges R-F AC/DC Cast
IIIU Radcal(3) 2 ranges R-F AC/DC Cast


Note: All Dynalyzer voltage dividers are 1000 meg ohm, frequency compensated to 100 kHZ.  1 to 150 KVP.  Radiographic milliampere range is 0-2000 mA,  2 kHz bandwidth.  Fluoroscopic range is 0-100 mA at reduced bandwidth.

(2) Main PC board changed. (3) Main PC board changed.