From news.cs.tut.fi!news.funet.fi!sunic!trane.uninett.no!eunet.no!nuug!EU.net!howland.reston.ans.net!agate!ames!lll-winken.llnl.gov!fnnews.fnal.gov!gw1.att.com!nntpa!not-for-mail Fri Sep 16 13:32:38 EET DST 1994 Article: 6209 of rec.radio.info Newsgroups: rec.radio.scanner,alt.radio.scanner,rec.radio.info Path: news.cs.tut.fi!news.funet.fi!sunic!trane.uninett.no!eunet.no!nuug!EU.net!howland.reston.ans.net!agate!ames!lll-winken.llnl.gov!fnnews.fnal.gov!gw1.att.com!nntpa!not-for-mail From: parnass@ihlpf.att.com Subject: Buying a Used Scanner Radio Message-ID: Followup-To: poster Originator: parnass@nwsf Keywords: FAQ food, old scanner models, hamfests Sender: news@nntpa.cb.att.com (Netnews Administration) Nntp-Posting-Host: nwsf.ih.att.com Organization: AT&T Bell Laboratories, Naperville, IL Date: Thu, 15 Sep 1994 15:43:44 GMT Approved: rec-radio-info@ve6mgs.ampr.ab.ca Lines: 687 Xref: news.cs.tut.fi rec.radio.scanner:13168 alt.radio.scanner:12457 rec.radio.info:6209 last changed September 12, 1994 | BUYING A USED SCANNER RADIO by Bob Parnass, AJ9S [NOTE: This article may not be reproduced in whole or in part on CDROMS, in bulletin boards, networks, or publications which charge for service without permission of the author. Free distribution is encouraged.] Anybody with enough money can buy a brand new scanner, but you can save lots of money if you get a good deal on a used scanner. Hamfests are probably the best place to find used radios, but you must be familiar with the equipment. Hamfests are repleat with older radios you won't see in today's catalogs. At last count, there were over 70 scanners and monitor receivers of various brands in my collection. I purchase most of my receivers at hamfests or horsetrade with other radio hobbyists. This article describes a few of the FM receivers in my collection, and is not meant to be complete. A Used Scanner May be a Broken Scanner Getting a bargain is not without some risk. I have had sellers look me square in the eye and tell me their radio worked fine -- when it really didn't. Buying a used portable scanner is riskier than buying a mobile or base model. Portable scanners are subject to more physical abuse and many have been dropped. If a radio has been dropped, the laws of probability dictate that the first point of impact was probably a corner, so be sure to examine each corner for evidence of trauma. Scanners used in mobile service are subject to vibration, dust, and temperature extremes. This shouldn't dissuade you from buying a used mobile scanner, but be aware of possible complications. You should have some recourse if the radio you buy turns out to be defective. If you can't fix the radio yourself, you can pay to have the manufacturer or a service clinic repair it for you. Several people have been pleased with Electronic Repair Center, in Franklin Park, IL, which repairs scanners for a flat fee. Call them at (708)455-5105 to find out their current rates. G & G Communications (telephone 716-768- 8151) is another scanner repair company. This family owned company repairs scanners and stocks parts for several older models. They are located at 9247 Glenwood Drive, LeRoy, NY 14482. Evolution of the Scanner It helps to understand some scanner history before shopping for a used scanner. You will likely see radios from many vintages at a hamfest, and should avoid buying early units unless you are a scanner collector. One of the earliest ancestors to the scanner was the converter. Manufactured by Tompkins (Tuneaverter), Petersen, Bearcat (Lil Tiger), Midland, and others, converters were made to operate in conjunction with AM radios. Then came wide band monitor receivers, in both tunable and crystal control models, like the Radio Shack PRO-2B. Truthfully, converters and tuneable FM receivers are interesting but don't work well by today's standards. While tuneable receivers were in vogue, solid state technologies supplanted tubes. Better performing, narrow band crystal controlled units, like the Sonar FR-105, followed. These units did not scan, rather channel selection was accomplished using a simple rotary switch. Sonar even made a 24 channel unit, model FR-2513, in which crystals were held in a rotary "turret." The earliest scanners, like the 1968 vintage Bearcat BCH, | BCL, and BCU models, did not provide individual channel | lockout capability. Electra didn't use the term "scanner" | and instead called these innovative radios "business | receivers." Other models, like the SBE Sentinel, employed | a "Channel 1 Bypass" switch so a user could lockout channel 1. The first scanners came in single band models, followed by multiband models. As two-way radio users started to populate the 450 - 470 MHz band, consumers were forced to pay a premium for UHF scanner coverage. Some multiband scanners, like the Electra's Bearcat III, required an optional circuit board for each band. There were scanner mutations, designs which never evolved -- odd combinations of AM broadcast receivers with VHF-FM receive capability, like the flamboyant turquoise Sonar Sentry FR-103 portables, Electra's Jolly Roger, and GE's Surveyor series. Lafayette Radio Electronics offered a few CB transceivers with VHF receiver capability. These poor performers didn't interest consumers of that era and you should avoid these models unless you are a scanner collector. The first programmable (crystal-less) scanners were difficult to program. Users had to look up frequencies in a code book and tediously program the information into the scanner in binary form. Some models, like the Bearcat BC- 101, Radio Shack COMP 100, and Tennelec MCP-1, resembled Altair or PDP-8 computers, with a row of 16 or so toggle switches. Instead of toggle switches, the Regency WHAMO-10 was programmed by breaking teeth from metal combs. The SBE Optiscan (and its Sears clone) required poking a series of holes in plastic cards which were then inserted into a slot on the front panel. Keyboard Programmable Scanners Both Bearcat and Regency, as well as Radio Shack offer some good models. I would avoid the Bearcat 100, and scanners made by AOR, JIL, Fox, Tennelec, and Robyn. Scanner features often differ not only by model but by manufacturer. For instance, most Radio Shack and Bearcat programmables allow enable/disable of the delay function on a per-channel basis. Older Regency units permit the delay to be enabled/disabled only globally, that is, for all the channels at one time. Radio Shack scanners contain a reasonable number of features. All the older Radio Shack scanners were made by General Research Electronics (GRE). Uniden began making scanner models for Radio Shack in the late 1980s, and now supplies about half the Radio Shack scanners. The older GRE-made models scan a bit slowly and have a higher level of synthesizer noise. Most have too much hysteresis in the operation of the squelch control, but this can be fixed completely by replacing one resistor. Good, detailed shop manuals are available for Radio Shack units for $5 - $12. In the name of cost cutting, some models have done away with the concept of a "channel bank", i.e. the ability to select/deselect a group of channels at a time. The bank concept was a good one. It may be inconvenient to operate a 30 channel scanner without banks (e.g. Regency MX3000, HX1000) if you operate the way many scanner hobbyists do. If you want to buy an American-made scanner, you will have to buy an old model. A few years ago, the Regency and Bearcat scanner lines were purchased by Uniden, a Japanese company, and production was moved to Asia. My favorite VHF/UHF receivers are the 300 channel Radio Shack PRO-2004, the newer 400 channel PRO-2005 and PRO- 2006, and the ICOM R7000 and R7100. The ICOM models are more "communications receiver" than a conventional scanner. Other favorites include the Bearcat 300 and 760XLT, Regency M400, and the Regency K500 (predates the M400), all of which include a "service search" feature. For portable use, I prefer the Radio Shack PRO-43 and Uniden/Bearcat 200XLT. Obtaining Crystals If you do purchase a crystal controlled scanner or monitor receiver, you will probably want to buy more crystals to cover local frequencies. Scanner crystals may be ordered from your local Radio Shack store or from one of the companies below. Be sure to specify the operating frequency you want and the brand and model of scanner. Some companies may ask you to send a schematic of the scanner or require more detailed information, like series or parallel resonance, load capacitance, etc. American Crystal Co. 1623 Central Ave. Kansas City, KS 66102 tel. 913-342-5493 Bomar Crystal Company 201 Blackford Ave. Middlesex, NJ 08846 tel. 908-356-7787 Cal Crystal Lab Inc. 1142 N. Gilbert St. Anaheim, CA 92801 tel. 714-991-1580 International Crystal Mfg Co. 11 N. Lee Ave Oklahoma City, OK 73102 tel. 405-236-3741 Jan Crystals Box #-6017 Fort Myers, FL 33911 tel. 813-936-2397 Monitor Crystal Svc 124 W Walnut St Watseka, IL 60970 tel. 815-432-5296 ICOM R-7000: At about $1000, this was once the top VHF/UHF receiver. 99 channel, multi mode coverage from 25-2000 MHz with a small gap at 1000-1025 MHz. Memory can be expanded to 198 channels by adding simple switch to pin 19 of memory IC8. Tuning knob lets you tune through parts of the spectrum much easier than using the SEARCH mode on conventional scanners. Selectable USB/LSB allows reception of new amplitude compandored sideband (ACSB) stations. S- meter doubles as discriminator meter to aid tuning. Useful search and store feature, reminiscent of the the Bearcat 250, searches between 2 limits and automatically stores new frequencies into channels 80-99. Audio and control interface for tape recorder. Noisy relay, activated when the receiver is tuned to frequencies above 520 MHz. Searches and scans slowly but can be sped up to about 12 cps by adding a resistor. Too big for permanent mobile use, but too nice to leave alone in the car. If you don't want to spend $1000, get a Radio Shack PRO-2004/5/6 instead. R-7100: At about $1300, this is the Cadillac of VHF/UHF receivers. 900 channel, multi mode continuous coverage from 25-2000 MHz. The radio RF/IF/AF portions of the R7100 are similar to the older R7000, but the R7100 is constructed using surface mount parts. Both the R7000 and R7100 are much more immune to intermod than the Uniden/Bearcat 760XLT and the portable PRO-43. The firmware in the R7100 is much more sophisticated. 9 banks of 100 channels. Further, you can associate each channel with 1 of 10 groups. Many possible ways to scan. 10 pairs of search limits. Search and store ("memory write") scan mode lets you store 100 frequencies instead of the 20 in R7000. Another R7100 improvement is that you can program up to 100 channels for the R7100 to skip while searching. R7100 has 2 VFOs ("windows"). Both the R7000 and R7100 scan slowly compared with PRO-2004 and PRO-2006, and that's a drawback. Both the R7100 and R7000 employ a noisy relay, activated when the receiver is tuned to frequencies above 520 MHz. Scanning a mixture of VHF and UHF frequencies serenades the Icom user with a very annoying clickety- clack, clickety-clack! UNIDEN/Bearcat and Electra/Bearcat Bearcat III (Electra): 8 channel crystal controlled scanner. Requires optional front-end circuit board for VHF-low, VHF-high, and UHF bands, but only 2 boards can be installed within the radio at the same time. Two crystal filters. No aircraft band coverage nor rescan delay. Front mount speaker sounds good. Strong local oscillator radiation often causes interference with other scanners in the same house. Bearcat IV (Electra): 8 channel crystal controlled scanner. Newer version of Bearcat III but has better IF filtering and contains front-end circuitry for VHF-low, VHF-high, and UHF bands. No aircraft band coverage. Three crystal filters. Front mount speaker sounds good. No rescan delay. Bearcat 12 (Electra): One of the last decent crystal controlled scanners. 10 channels. Variable scan speed up to 20 ch/sec. Single delay on/off switch. Front mount speaker sounds good. Manual contains schematic. Selectivity is poorer than programmable models, like the 300, allowing adjacent channel interference. Covers VHF- low, VHF-high, and UHF bands but no aircraft band coverage. Crystal positions must be arranged by band. BC101 (Electra): First Bearcat synthesized unit. 16 channels, no priority. Frequency programmed in binary by setting toggle switches on front panel after looking up code in code book. No frequency readout. Uses custom IC for CPU, now discontinued, so factory authorized service is no longer available. I have four of these units. DC operation requires optional mobile power supply. BC100 (Electra): First programmable portable scanner. Be prepared for at least one repair in the first year. Early units, with threaded antenna connector, have high frequency of repair, particularly LCD readout, keyboard, and battery holder. No battery backup. Poor case design in early units caused battery to disconnect from radio, resetting microprocessor and clearing memories. No priority channel or aircraft band. Some people swear by the BC100, others swear at them. BC220 (Electra): 20 channels. Reasonable number of features but 20 channels doesn't seem enough. Service Search for Marine and Aircraft. LED readout. Good scanner, but tinny audio. BC20/20 (Electra): A BC220 but with 40 channels. A maximum of 20 channels can be scanned at one time. Reasonable number of features. Service Search for Marine and Aircraft. LED readout. Good scanner, but tinny audio. BC250 (Electra): 50 channel model, rich in features, but lacks aircraft band and 144-146 MHz. Search and Store feature extremely useful for finding federal frequencies. Clock. High frequency of repair. Power transistors not heat sinked adequately, causing heat damage to surrounding components and circuit board. Failure of Q204 on the feature board known to cause odd display readings. Digital circuitry very sensitive to glitches caused by static and AC line spikes. Avoid 1978 or earlier vintage units. All BC250s use custom ICs (e.g., IC6, a divider chip, mfd. by Exar), which are now discontinued, so factory service is no longer available from Uniden. BC260 (Electra): Super heavy duty metal cabinetry and lit controls, aimed at mobile use for firemen, police, etc. Few frills, only 16 channels, no aircraft, but generous coverage of federal bands omitted in the older Bearcat scanners. Good sensitivity. Lots of audio. Good internal construction. Backlit keyboard allows operation in the dark, but the keyboards on some units require high pressure to operate. Brightness control for display and keyboard, but multiplexor circuitry for vacuum fluorescent display produces audible whine which may be annoying in a quiet room. Backlighting may fail in some units due to poor contact on connector used to fasten light panel to front circuit board. 9 volt regulator transistor Q28 (TIP29) may fail, causing blank display while leaving audio intact. Method of connecting an external speaker is awkward. BC300 (Electra): 50 channel top of the line scanner. Service Search feature contains 11 ROM banks of preprogrammed channels. Switching power supply failure noted in early units due to insufficient capacitance - component value was changed in newer units. Schematics show at least 100 components changed between earliest and later units. Preset squelch pot, mounted internally on circuit board, misadjusted in new units - adjustment usually required after burn-in period. Good sensitivity. Built in clock. I leave it on 24 hours a day. This is a favorite. BC350 (Electra): 50 channels in 5 banks. Includes aircraft. Used to be Bearcat's top of the line, overpriced scanner but never very popular. Dual use keyboard and display allowed 8 text characters to be associated with each channel, a feature clumsily implemented, and awkward to use. Units plagued with various hardware problems including bad memory ICs and short life power transformers. Firmware bugs without cures. The BC300 is a much better scanner than the BC350, and at a lower price. 800XLT (Uniden): 40 channels in two banks. Covers 806-912 MHz, as well as of vhf, uhf, and aircraft bands. Receives 10 meter fm and all of 6 meters, as well as federal portions of vhf and uhf bands. Fewer birdies on vhf-lo band than other scanners. Scans and searches very fast. Clean, robust audio output. Extremely sensitive, but very prone to overload by strong signals when connected to outdoor antenna. Too much play (hysteresis) in squelch adjustment - can be improved by changing one resistor. Positive terminal in memory backup battery holder installed backwards in early units, allowing memory loss when scanner unplugged from AC outlet. Tunes in increments of 12.5 KHz on 800 MHz band, whereas cellular telephones are on 30 KHz channels. BC100XLT (Uniden): Excellent 100 channel portable with 10 priority channels. Unique feature tells whether a given frequency has already been memorized. Generous coverage of conventional bands, including commercial aircraft, but no 800 MHz. Decent leather-like case. Slide-on 550 mAH NiCd battery pack. BC200XLT (Uniden): Excellent 200 channel version of BC100XLT portable scanner but includes 800 MHz band. 10 priority channels. Unique feature tells whether a given frequency has already been memorized. Decent leather-like case. Slide-on NiCd battery pack. Regency TMR series: First generation crystal scanners. Come in all varieties of band coverage. Models with both UHF and VHF bands must use separate antennas for each band (disadvantage in mobile installations, but can be overcome by connecting two front ends via a capacitor). Not sensitive enough to cover the entire 30 - 50 MHz range in a single model. There three versions of VHF-low band coverage depending on the part of the 30 - 50 MHz band covered (LL, LM. and LH). TMR scanners use unsocketed incandescent bulbs for channel indicators which require periodic replacement. Easy to crystal: Radio Shack crystals work well. TMRs usually $2 and up at hamfests, often in poor condition. Don't pay more than $50, even if mint. Front ends must be tuned for selected portions within the bands for best sensitivity. Wide IF selectivity troublesome in urban/suburban areas. Primitive digital scanning circuitry may become confused at times. but power off/on restores sanity. Replace aging capacitors in the scanning circuits. You can find a TMR8H eight channel high band unit most often. TME series: The base versions of the TMR models. Both the TME and TMR models share many common circuits but the base versions contain speakers mounted on the front panel. The most common TME model is the TME8 H/LM eight channel dual band scanner in a metal cabinet with wood coloring. ACTR series: Replaced the Regency TMR units. By the time Regency made the ACTR units, they no longer offered different models for different parts of the 30 - 50 MHz band. Look for the later ACT series, e.g., ACTR-106 (10 channel tri band) or ACTR20/6 (20 channel tri band), used light emitting diodes for channel indicators instead of incandescent bulbs. Available in 1 to 20 channel models - most are multi band receivers. Somewhat wide selectivity. Not all that bad a deal if cheap. ACTE series: The base versions of the ACTR series. The ACTE and ACTR circuitry is similar, although the base versions contain speakers mounted on the front panel. The most common ACTE model is the ACTE8 H/L eight channel dual band scanner in a black metal cabinet. WHAMO-10: Regency's first synthesized scanner. Appearance more like a crystal scanner, with a single LED per channel. User has to break off teeth on a metal 'comb' for each channel according to a code book. External frequency control unit DFS-5K optional. UHF VCO reference oscillator drifts on some units. Soldered sheet metal shields around some circuitry make access to some components difficult for servicing. Comb sockets prone to bad connections after moderate use. Not recommended due to maintenance difficulties. K500: Nice wood-like cabinet. 40 channel model with every feature Regency could dream of in one scanner, except aircraft band. Idle tone bypass feature for mobile phone stations works about 50% of the time. Weather alert feature. Service Search in several banks. Search and Store facility not implemented as well as BC250, but better than none. Built in clock when radio off or in manual mode. Can be programmed out of band. Reasonable performance, but sensitivity could be better. Spring contacts on membrane keyboard may need soldering after prolonged use. K100: Bare bones version of the K500. 10 channels, no priority feature. Same wood-like cabinet and reasonable performance as K500. Spring contacts on membrane keyboard may need soldering after prolonged use. M400: 30 channel replacement for K500. Service Search, but no aircraft. Easily programmable out of band. Built in clock when radio off or in manual mode. Backlit keyboard good for night viewing and mobile use but generates RFI into nearby SW receivers. A favorite. MX3000: 30 channel replacement for M400, but basic features only. Nice lit keyboard, but may cause RFI into nearby SW receivers. Easily programmable out of band, but no aircraft. All 30 channels are in a single bank, and lack of direct channel access make this model more difficult to operate. Good first scanner. M100: 10 channel unit. Same as MX3000 except different color and fewer channels. Nicely lit keyboard, but may cause RFI into nearby SW receivers. HX1000: Good, fairly rugged, 30 channel handheld synthesized unit. Generous out of band coverage but no AM aircraft coverage. Built by Azden. Very sensitive on UHF, but annoying audio hiss leaks through speaker when squelched. Belt clip chintzy, but can be directly replaced with better clip from Kenwood TR2600A. Like the MX3000, all 30 channels are in a single bank, and lack of direct channel access make this model more difficult to operate. Low discount price makes this best choice for programmable portable. HX650/H604: 6 channel crystal portable. Likely made by Sanyo. Same as Fannon and Bearcat Thin Scan units, (except that Bearcat has 10.8 MHz IF frequency, and is harder to get crystals for), but scans faster. Small size and common crystals (available at Radio Shack), make this 1st choice for bare bones portable scanner. Radio Shack PRO2004: Top of the line, wide band scanner for 1987. After a diode is cut, enjoy continuous coverage from 25-520 and 760-1300 MHz, AM, NBFM, and WBFM. Has 300 channels in 10 banks of 30, backed up by conventional 9 volt alkaline battery. Any channel can be designated the priority channel. Scans and searches fast. Lots of well designed features, like 10 pairs of search limits, Lockout Review, default search increment and emission mode. Sound Squelch allows skipping dead carriers during search or scan. Metal cabinet, good internal construction and shielding, but no mobile mounting bracket or DC power cord. Soft touch membrane keyboard. Good sensitivity and selectivity. Very good radio. PRO2005: Radio Shack's top of the line scanner for 1989 and scanner of choice. Essentially a size reduced PRO-2004 with surface mount components and 400 channels. Some people think the small knobs, smaller display, and plastic cabinet are a setback from the 2004. The smaller size, real rubber keyboard, and vertical front panel make it easer to use mobile, although there is no mobile mounting bracket available and the keyboard is not backlit. More sensitive than the PRO-2004 but 800 MHz signals leak through into the commercial aero band. Highly recommended. PRO2006: Radio Shack's 1994 top of the line scanner. Essentially the same as PRO-2005 but scans faster. Probably the best scanner made to date. Highly recommended. PRO34: Portable scanner with 200 channels and 800 MHz coverage. Ten "monitor" channels. Operates from AA cells. Slow scanning, low audio output, and chintzy plastic case detract from an otherwise good performance. No decent leather case available from Radio Shack. If you need a portable with 800 MHz, get a Bearcat 200XLT. If you can't get a 200XLT, get a PRO-34. PRO2021: Base/mobile scanner. 200 channels in 10 banks, LCD display and raised rubber keys. Lots of memory but scans too slowly and lacks 800 MHz. Ten "monitor" channels. Radio Shack seemed to have an overstock of 2021s as they were on sale for such a long time. Close out price dipped to about $200, which made it a nice scanner for beginners. PRO2001: Early, single bank 16 channel programmable. Reasonable coverage of the 3 traditional bands, minus aircraft band. LED digital display as well as an LED per channel. Mechanical lockout switch for each channel. Delay is either on or off for all channels at a time. High synthesizer noise level. Troublesome plated through holes on digital board in some units renders radio virtually unfixable. Could never get mine to work more than a few days in a row; always another bad connection. Some owners have no trouble. PRO52: 8 channel VHF-Lo/Hi base unit. No UHF band or provision for mobile operation. Good little scanner despite limited frequency coverage and Spartan lack of frills. Crisp squelch action and good audio, helped by a front mounted, vertical speaker. PRO2003: Radio Shack's 1986 top of line. 50 channels + 10 FM commercial broadcast band channels. Includes aircraft. Good frequency coverage and functionality, but at a high price. Poor human engineering: difficult to read keyboard makes the PRO2003 hard to operate unless in a well lit room. Keyboard label coloring improved on newer units. Rather slow scan rate and high price. Although there are provisions for 12VDC operation, the cabinet shape and lack of mounting bracket makes mobile operation impractical. Scan rate only 8 channels/sec vs. 15/sec in Regency and Bearcat. Causes RFI: Plastic case permits scanner to radiate signals into nearby receivers. PRO30: 16 channel programmable portable with aircraft band. Good frequency coverage. Extra controls on top allow control of SCAN, MANUAL, and PRIORITY functions while worn on belt. Good belt clip. Low audio output. Plastic case prone to break at BNC antenna connector under severe use, vs. metal frame in Regency HX1000. High price, no discounts or sales yet. I had 6 or 7 PRO30s, having to return them several times during the 1 year warranty, although other owners have had little or no trouble. Troubles included oscillation in IF stage, no UHF band reception, case broken around base of antenna connector, etc. PRO24: Only 4 channels in this crystal controlled portable. Covers the three basic bands, but no aircraft. Easy to obtain batteries and crystals. Characteristic Radio Shack squelch problem, fixable by changing one resistor. All- plastic case larger than Bearcat Thin Scan and clones. Craig (division of Pioneer) 4530: Japanese 10 channel crystal controlled 3 band unit. Also available under Plectron name but in different cabinet. No aircraft band. Deluxe features like priority, trimmer capacitors for netting each channel, front panel speaker, and rugged metal cabinet make this unit a winner. Channel lockout slide switches have finite life. Replacing burned out incandescent channel lamps not fun. Grab a 4530 if you find one in good condition. Sonar: Sonar made several crystal controlled scanners and channelized monitor receivers which shared the same RF circuitry. Each radio was housed in the same size metal case and worked on both 120 VAC and 12 VDC. The models differed in the number of channels, the band coverage, and whether individual channels could be locked out. Although they used a 10.7 MHz first IF, Sonar radios require parallel resonant crystals different from the common series resonant crystals used in Regency and Radio Shack scanners. Some Radio Shack crystals will work in Sonar units, but more often they oscillate a few kHz off frequency and are unsuitable unless changes are made to the oscillator circuitry. Therefore, beginners should avoid these radios. Typical Sonar squelch has long time constant causing a long noise burst at the end of each transmission. FR-104, FR-105: 6 channel monitor receivers covering 25 - 50 MHz or 150 - 175 MHz. Manual channel selection, i.e., no scanning. Early models are identified by an 11 pin connector on the rear and they could be used with an optional NiCd battery pack and charger which bolted to the rear panel. Later models used Cinch Jones connectors with flat contacts. Optional tone decoder board. FR-2512, FR-2513: 24 channel versions of the FR-104 and FR-105 monitor receivers. Manual channel selection, i.e., no scanning. FR-2514, FR-2515: 8 channel scanners. Channel 1 priority. Recommend you avoid these models as there is no way to lockout a channel from the scan sequence. FR-2526, FR-2526, FR-2528: 10 channel scanners covering various combinations of 3 bands. Each channel could be locked out. Channel 1 priority. Sonar #chan- VHF VHF UHF lock- Model nels low high scans? outs? ___________________________________________________ FR104 6 X no FR105 6 X no FR2512 24 X no FR2513 24 X no FR2514 8 X yes no FR2515 8 X yes no FR2526 10 X yes yes FR2526 10 X X yes yes FR2528 10 X X yes yes Table 1. Summary of Sonar base/mobile monitor and scanner receivers Tennelec Manufactured the first synthesized scanners. Company went out of business several years ago. Schematics and parts difficult to obtain. Radios reputed to be poor performers. Got my MS-2 and MCP-1 basket cases for free and sometimes regret taking them. Not worth fixing unless you have access to DTL/RTL chips and circuit diagrams. -- ============================================================================== Copyright 1994, Bob Parnass, AJ9S AT&T Bell Laboratories - parnass@ihlpf.att.com - (708)979-5414