USM-281e

From Fusselman.org

I finally bought my oscilloscope, a required implement for a variety of projects I have planned. I ended up with a Navy surplus DuMont 190 model (which may be it's mil-spec ID) "USM-281e". According to Fair Radio Sales, it's similar to the model "D", and is made up of a OS-246A display unit along with an AM-6566 dual-trace input module and a TD-1086 time base-delay module. I'd not realized that it was modular at all, until this morning when I accidentally slid the lower tray out and then started doing some research.

I did some looking online for a manual today and came up with an antique paper copy, probably from when the scope was new, which was sometime in the late 70s. The buy-it-now price was $40. I was really hoping for a PDF with some detailed specs and whatnot. I ended up finding a very good tutorial online.

I've compiled the following specs:

• Solid State (This surprised, and pleased, me quite a bit)
• Frequency Response: DC to 50 MHz
• Deflection: 5 mv to 10 V/div (11 steps)
• Maximum Input Voltage: 400 VDC peak AC or DC coupled.
• Time Base Ranges 0.1 us-2 s/ div (23 steps)
• Two square-wave calibration outputs (1 KHz):
  • 300 mv
  • 1 V
• Physical Characteristics:
  • Size: 11.5x8x21.5 (inches)
  • Weight: 44 lbs (20kg)