A first-generation, low-cost Cherny-Turner spectrometer has been tested. Dimensions for this spectrometer were developed using industry-leading optical design software, engineering drawings, and Dimensions for Telescopes and Spectrometers (Zemax). The spectrometer's focal length (150mm) was determined. Using two (2) concave mirrors, the first woman is to collect the light radiation from the source and the second woman is to focus the rays to a (CCD) camera (Charge-Coupled-Device). The manufactured spectrophotometer can analyze wavelengths between (1000-300) nanometers. Calibration of the axes of the spectrometer using major light sources of generally known lengths, before taking measurements the horizontal axis is calibrated from the pixel system to the wavelength, and the vertical axis is reversed from count (cont) to intensity. This spectrometer has a resolution (full width at half maximum) (FWHM) of (0.7) nanometers. Spectrophotometric methods were used in the power range (15,22,38,40,44,47,50,57,58,61 W) and constant pressure (6.5 Tor). Spectrophotometers are typically used in laboratories to test plasma parameters using the optical emission method and perform calculations using the slope (line ratio) method. The objective in this research is to use optical emission spectroscopy to calculate the plasma electron temperature (Te) of an argon gas plasma.