PRO2004.6 Part 3/4 Taping Facility A tape recorder can be connected to the TAPE phono jack on the rear panel, which provides 600 mV of audio at a 10,000 ohm impedance. In addition to a rear mounted external speaker jack, there is a headphone jack on the front of the scanner. Basic Performance To evaluate sensitivity, the $400 PRO-2004 was compared with a $950 ICOM R7000 and a $300 UNIDEN/Bearcat 800XLT. Since a signal generator was not used, quanti- tative measurements could not be made. Instead, various antennas were switched between radios, signals from stations were compared by ear, and the results tabulated. Simply put, the PRO-2004 is sensitive enough to allow one to hear what needs to be heard, and not so sensi- tive as to be overloaded by strong signals. On 850 MHz, signals were readable on the PRO-2004 which couldn't even be detected on the R7000. Although the 800XLT is the most sensitive radio of the three tested, it suffers from images and overload much more than the PRO-2004 or R7000. The PRO-2004 has a 10 dB attenuator, operable by a slide switch on the rear, but its use has been unnecessary thus far. The up conversion design of both the ICOM and Radio Shack units allows use of a very high IF (intermediate frequency), which helps avoid image problems. The PRO-2004 owner's manual doesn't list the IF frequencies directly, but a good guess is that the first two IFs are 610 MHz, 70 MHz. The third IF looks something like 455 KHz when using AM or NBFM, and perhaps 10.7 MHz when the WBFM mode is selected. The PRO-2004 is slightly more selective on NBFM than the 800XLT. WBFM selectivity is rated at about twice as wide as the ICOM R7000. The audio output quality is good, although it seems to lack the punch of the 800XLT audio. The top mounted speaker directs the sound at the ceiling, but adding an external speaker would allow the sound to be directed at the user. Unfortunately, the audio level of AM signals is somewhat below that of NBFM signals, requiring a dif- ferent setting of the volume control. When scanning both AM and NBFM modes, one has to find a compromise position of the volume control. The PRO-2004 squelch control has a bit too much hys- teresis, a trait inherited from its ancestors. It's like having too much play in a car's steering wheel, or backlash in a gear set. This hysteresis forces one to keep the squelch at a tighter setting, missing weaker signals when scanning or searching. The Bearcat 800XLT has this trait also, but the fix is simple. I've successfully eliminated this problem completely by replacing a single resistor on the 800XLT, as well as the PRO-2002, PRO-2003, and PRO-24 scanners. Mechanical Construction The PRO-2004 is heavy. It is enclosed in a metal cabinet, but has a plastic front panel. If one is going to pay $400, one deserves to own some metal. The entirely plastic cabinet of the older PRO2003 allowed wideband noise to radiate out of the scanner and into nearby shortwave receivers. There is a single BNC antenna connector on the rear of the PRO-2004, and a single telescoping antenna is sup- plied. This differs from the 800XLT which has 2 "Motorola type" antenna connectors, one reserved for the 800 MHz band. Internal construction is excellent. Most stages are completely enclosed in their own individual shielded boxes. Interstage shielding is very important in a wide band receiver, to prevent it from "hearing itself", an undesirable phenomena which results in "birdies".2 The shielding is much better in the PRO- 2004 than in the 800XLT, which uses no shielding around the 800 MHz converter stage, and probably accounts for some of the birdies in the Bearcat. Frequencies and other indicators are displayed on a backlit LCD (liquid crystal display) panel, and the level of backlighting can be dimmed by a pushbutton switch. The flat membrane keyboard has a nice feel. Only slight pressure is required for actuation, and key depressions are confirmed by a mild "beep" audio tone. The PRO-2004 might be too large to fit under the dash- board of compact cars. Although it can be operated on 12 VDC, neither a mobile power cord nor mounting bracket are provided. These items were included with earlier Radio Shack models. The AC power cord is not detachable, and would have to be bundled up to keep it out of the way in a mobile installation.  Downloaded From P-80 International Information Systems 304-744-2253