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Buying a Used Scanner
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last changed March 12, 1995 |
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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
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Copyright 1995, Bob Parnass, AJ9S
AT&T Bell Laboratories - [email protected] - (708)979-5414
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