Hobbies And Interests
General Features
The Cobra 139 XLR includes a built-in 8-ohm speaker and a plug-in type microphone with a push-to-talk switch. It also offers an advanced Phase Lock Loop (PLL) synthesizer that compares the phase of the input signal with the output-oscillator's phase and then adjusts the frequency of its oscillator to keep the phases matched for superior signal quality. The PLL system is used in the AM mode as well as both the upper and lower single-sideband (SBB) modes on 40 channels ranging in frequency from 26.965 to 27.405 MHz. It also includes four built-in meters that show the relative power output, the received signal strength, the modulation percentage and standing wave ratio (SWR).
Transmitter
The Cobra 139 XLR produces a power output of four watts in the AM mode and up to 12 watts in the SSB mode with a frequency response for both modes between 350 to 2500 Hz. Its output impedance (the opposition of its output terminals to the flow of an alternating current (AC) of a particular frequency) is measured at 50 ohms and its intermodulation distortion (in SSB mode) falls between the third and fifth order at levels of more than minus-25 decibels and the seventh and ninth order when levels are more than minus-35 dB. It also utilizes a 7.8 MHz, crystal-lattice type SSB filter with a range between 6 at 4.2 KHz to 60 dB at 7.0 KHz.
Receiver
The Cobra 139 XLR includes a receiver that operates in both AM and SSB modes with features such as automatic noise limiting, noise-blanker circuitry and adjustable, automatic gain control (for optimum signal reception) as well as a selectivity level that ranges from 6 dB at 4.2 KHz to 60 dB at 7.0 KHz. Its sensitivity is measured at less than .25 microvolts (uV) for 10 dB in the SSB mode and less than .75 uV for 10 dB in the AM mode. Its frequency response in both modes ranges from 350 to 2500 Hz.
Other Specifications
The Cobra 139 XLR includes a height of five inches, a width of 13.5 inches and a depth of 13 inches. It weighs 10 pounds and operates in a temperature range as low as minus-22-degrees Fahrenheit to as high as 122-degrees F. Although not supplied, an external 8-ohm, 3.5-watt speaker can be connected to the PA speaker jack (on the rear panel) to be used as a public-address system.