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TUCoPS :: Radio :: buyused.txt

Buying a Used Scanner




 last changed March 12, 1995                                  |

 Lines changed since the previous issue are marked with a  |  |
 character in the right margin.                               |

                 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 older
 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  400  channel  Radio  |
 Shack  PRO-2005 and PRO-2006, the Uniden/Bearcat BC9000XLT,
 and the ICOM R7000 and R7100.  The  ICOM  models  are  more
 "communications receiver" than a conventional scanner.

 For portable use, I  prefer  the  Radio  Shack  PRO-43  and  |
 Uniden/Bearcat BC3000XLT.


                     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, 800-725-1426

             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.

 BC860XLT (Uniden): 100 channel table top  unit.   Can  lock  |
 out  10  channels during search.  Good performer except for  |
 images.                                                      |

 BC890XLT (Uniden): Same as Radio  Shack  PRO-2036.   Tuning  |
 knob.   200  channels,  global delay.  Count, AUX, and Auto  |
 Store features.  Scans and searches fast.  Accepts optional  |
 CTCSS  board.   Dual  conversion  with 10.8 MHz first IF --  |
 lots of images and  birdies.   Prone  to  severe  intermod,  |
 especially when used with an outdoor antenna.                |

 BC9000XLT (Uniden): High quality base using  up-conversion.  |
 500 channels in twenty banks.  Tuning knob.  Selectable AM,  |
 NFM, WFM modes.  Very fast scan and search.  Can  lock  out  |
 50   channels   during   search.    Delay   and  attenuator  |
 independently programmable  for  each  channel.   Effective  |
 Auto Store feature stores unique frequencies.                |

 BC100XLT (Uniden): Very good 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):  Very  good  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.

 BC2500XLT (Uniden): 400 channel portable with tuning  knob.  |
 Plagued  by  intermod  and  images.   Early  units  drained  |
 batteries quickly even while turned off.

 BC3000XLT (Uniden): Excellent  400  channel  portable.   Up  |
 conversion.   Very  fast scan, search, and intelligent Auto  |
 Store.  Mode, attenuator, and delay  settings  programmable  |
 for each channel.                                            |


                           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.

 PRO-2035: Radio Shack's 1995 top of the line  1000  channel  |
 base  scanner.   Cumbersome  100 channel bank size.  Tuning  |
 knob.  Poor dynamic range.  10 linkable search banks.  Dumb  |
 Auto  Store  feature  stores  the same frequencies over and  |
 over.                                                        |

 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.

 PRO2022:  Base/mobile  scanner.   Like  the   PRO2021   but
 includes  the 800 MHz band.  Cellular images throughout the
 847.6 - 869 MHz range.  Includes power saver  circuit,  odd
 for  a  base  unit,  which  can  clip  the  first part of a
 transmission.

 PRO2036: Same as  Uniden/Bearcat  BC890XLT.   Tuning  knob.  |
 200  channels,  global  delay.   Scans  and  searches fast.  |
 Count, AUX, and  Auto  Store  features.   Accepts  optional  |
 CTCSS  board.   Dual  conversion  with 10.8 MHz first IF --  |
 lots of images and  birdies.   Prone  to  severe  intermod,  |
 especially when used with an outdoor antenna.                |

 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.                       |

 PRO62:  Good  portable  200  channel   scanner   using   up  |
 conversion.   Similar  to  PRO-43 but no military air band,  |
 different upper frequency  limit,  and  slightly  different  |
 IFs.   Selectable  AM/NFM  modes.  Better intermod immunity  |
 than PRO-43.                                                 |

 PRO43:  Good  portable  200  channel   scanner   using   up  |
 conversion.   Covers  military air band.  Selectable AM/NFM  |
 modes.  Intermod in 160 - 162 MHz railroad band.

 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.



        Plectron and Motorla Alert Monitor Receivers

 In the 1960s and 1970s, thousands of firemen and  ambulance
 squad members came to rely on their transistor Plectron and
 Motorola Alert  monitor  receivers.   They  have  now  been
 replaced  by  portable  pagers,  and are often available at
 hamfests in the $5 - $25 range.  Since many  are  in  rough
 condition  and  need  repair,  a  hamfest special is better
 suited for hobbyists who like to fix their own radios.

 Plectron and Motorola Alert  crystal  controlled  receivers
 are excellent for dedicated monitoring of local frequencies
 -- a task for which you wouldn't want to tie  up  your  400
 channel  programmable  scanner.   These  radios  are  fixed
 channel units and do not scan.  They can  be  powered  form
 117VAC or 12VDC with the proper mobile cord.

 The audio quality on a Plectron P1 or  700  series  is  far
 better  than any consumer grade scanner and the sensitivity
 and intermod immunity is outstanding if  aligned  properly.
 The  Plectron  500 series is less desireable.  The Motorola
 Alert monitors are pretty good, although  the  audio  lacks
 bass.

 No single Plectron or Motorola Alert monitor can cover  the
 entire  30-50  MHz  band, and there were versions optimized
 for each portion of the band. There were different  "split"
 models to cover segments of VHF-hi band, too.  Although UHF
 versions were made, they are somewhat rare.

 Both  brands  of  receiver  require  special  crystals.   I
 sometimes  use  Radio  Shack's generic 3rd overtone scanner
 crystals in the Plectrons but they oscillate on frequencies
 far away from their marked frequencies.  That's because the
 Plectron oscillator is designed to be used with  a  crystal
 which   oscillates   on   its  fundamental,  not  overtone,
 frequency.

 If you  find  the  squelch  on  your  Plectron  700  series
 receiver  has  too  much  hysteresis,  replace  R96, a 180K
 resistor, with a 560K resistor.  On the P1, the resistor is
 designated R81.

 Parts for Plectron receivers are available from:


                 Plectron
                 Plectron Place
                 P.O. Box 960
                 Imboden, Arkansas 72434

                 telephone 1-(501)869-2877
-- 

==============================================================================
                       Copyright 1995,  Bob Parnass, AJ9S
           AT&T Bell Laboratories  -  parnass@att.com - (708)979-5414



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