parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (01/07/86)
x Owner's Report: Uniden/Bearcat 800XLT Scanner Bob Parnass, AJ9S Manufactured in Taiwan, the 800XLT is the first programmable Uniden/Bearcat scanner to cover a portion of the 800 MHz band. Covering 40 channels in 2 banks the 800XLT is speci- fied to receive in the following ranges: TTTTAAAABBBBLLLLEEEE 1111.... 800XLT Frequency Coverage ________________________ | 29 - 54 fm| | 118 - 135.975 am| | 136 - 174 fm| | 406 - 512 fm| | 806 - 912 fm| |________________________| Only a portion of the new 902-928 MHz ham band is covered. Differs From Past Models There are several differences between this scanner and its Bearcat predecessors. - There is only a single scan/search speed: fast! - 800XLT channel banks contain 20 channels, not 10 as in previous models. Although we should be thankful for the inclusion of a channel bank feature, doubling the number of channels in a bank is a step backwards. - Scan delay, channel lockout, and priority enable are indicated by separate, colored LEDs rather than the numeric display, making a colorful light show. - Both the selectable scan delay and the priority sam- pling period are 3 seconds vs. 2 seconds in the older scanners. Although a matter of personal preference, I like the 3 second scan delay, but would opt for a 1 or 2 second priority sampling period. - Despite claims on the 800XLT box to the contrary, a 2 digit channel counter is displayed while scanning, as in the BC350, rather than "rolling zeroes" of the BC210/220/250/300. This is unfortunate, as rolling zeroes make it easier to discern what channels are locked out from scanning without having to step through each one manually. - The keyboard has a good feel, although quite different from the "chicklet" keyboards on Bearcat 250 and 300 scanners. Keys travel further, with less of a positive click. The 800XLT keyboard is much easier to read, as each key has its function printed right on the keytop, rather than labeled above it on an inlay. - The 800XLT seems to lack "window detection" circuitry, so the scanner may stop prematurely (off frequency) in the SEARCH mode. - There is no date of manufacture stamped on the cabinet. - Mobile DC power cord is optional, but is supplied as standard equipment with other Bearcat scanners. Inside Appearance Pleasing The inside of the 800XLT consists of 3 circuit boards: 1. a main receiver board, containing vhf/uhf front ends, IF stages, audio amplifier, 2. a feature board, containing microprocessor and key- board logic, and 3. an 800 MHz front end board, which uses surface mount components. The boards appear very neat, and it is obvious that computer aided design and automated component insertion techniques were used. What a welcome change from the chaos inside a hand assembled BC250! No schematic diagram is furnished. Whereas the identity of many of the ICs in earlier Bearcat scanners was obscured by the use of "house numbers", the ICs in my 800XLT are clearly marked with their original designations (e.g. National LM382). This makes repair easier, as one may obtain parts from several sources rather than being forced to buy from Uniden. Side-by-Side Performance Comparison Side-by-side tests were performed, switching a Butternut SC3000 tri-band antenna at 20 feet among 3 scanners: the 800XLT, a new Bearcat 260, and an old Bearcat 300 workhorse. The test equipment used was a pair of human ears, which we all use when scanning. As the following table shows, the 800XLT was more sensitive on some frequencies, but suffered much more overload from strong signals. This is important if the 800XLT will be used with an outdoor antenna. The 800XLT had fewer annoying birdies than the other models tested. TTTTAAAABBBBLLLLEEEE 2222.... Performance of Bearcat 800XLT vs. 260 vs. 300 _____________________________________________________________ | Band || Bearcat 800XLT | Bearcat 260 | Bearcat 300 | |___________||__________________|________________|________________| | 30-37 MHz|| more | more | less | | || sensitive | sensitive | sensitive | | || | | | | || weak | moderate | moderate | | || birdies | birdies | birdies | | || | | | | || overloaded by | no overload | no overload | | || paging, police | detected | detected | | || mobile phones | | | |___________||__________________|________________|________________| | 37-50 MHz|| equally | equally | equally | | || sensitive | sensitive | sensitive | | || | | | | || overloaded by | no overload | no overload | | || paging, police | detected | detected | | || mobile phones | | | |___________||__________________|________________|________________| | vhf || more | N/A | less | | aircraft || sensitive | | sensitive | |___________||__________________|________________|________________| | vhf-hi || slightly more | slightly more| slightly less| | || sensitive | sensitive | sensitive | | || | | | | || overloaded | no overload | no overload | | || by paging | detected | detected | | || | | | | || heard 162.55 wx| | | | || on 147.19 | | | | || and elsewhere | | | |___________||__________________|________________|________________| | uhf || more | less | less | | || sensitive | sensitive | sensitive | | || | | | | || overloaded | no overload | no overload | | || by paging | detected | detected | |___________||__________________|________________|________________| On the 800 MHz band, several police, business and cellular telephone stations were received using the supplied 3" antenna. Clear reception of a repeater used to dispatch Chicago Tribune photographers was possible from 50 miles distant. The 800XLT audio output is clean and strong, with little synthesizer whine. Early Problem Fixed: Memory Loss My 800XLT lost its memory contents when unplugged from 117VAC, even though loaded with a fresh pair of alkaline AA batteries. The problem was traced to a metal contact, installed backwards in the battery holder. Repair required desoldering a red wire, repositioning the contact, then resoldering the wire. No further memory problems have been encountered. Too Much Hysteresis in Squelch There is too much "free play" in the stock 800XLT squelch control, the same affliction designed into Radio Shack scanners. The remedy consists of replacing the 860K ohm resistor on pin 14 of the MC3359P IC with a 2.2M ohm resis- tor. Not As Selective as Older Bearcats At -55 dB @ +- 25 KHz, the 800XLT IF selectivity is not as good as the BC350 and BC300, which are rated at -60 dB @ +- 25 KHz. The wider selectivity causes the scanner to stop prematurely in the SEARCH mode, and makes it difficult to determine, for example, if a station is transmitting on 855.2500 as opposed to 855.0125 MHz. Since the 800XLT tunes in 12.5 KHz steps on the 800 MHz band, the wider selectivity is handy when scanning telephone cell sites, which are on channels spaced on 30 KHz apart. Overall Evaluation The 800XLT is the most conventional and easiest to operate of the new 800 MHz-capable scanners. It is plagued neither with the slow scan/search rate of the Regency MX7000, the low audio output of the MX4000, nor the unfriendliness of the Yaesu scanning algorithms. The 800XLT's tendency to overload on strong signals and awk- ward squelch action detract from an otherwise good perfor- mance. -- =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414