RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
vintage Heathkit IM−2400, 512 MHz Handheld Frequency Counter kit is one the
Heathkit kits which appeared on eBay. I have been saving the images in order
to preserve the history. The constantly growing list is at the lower right.
The first instance I could find for IM−2400 being offered for sale was in the
Winter 1981 Heathkit catalog, at a cost of $139.95 ($429.59 in 2021 money per the
BLS) as a kit or $179.95($552.37 in 2021) assembled and tested. A comparable
handheld frequency counter today is the TTi PFM3000
3 GHz Hand-Held Counter, at a cost just south of $200.
"The Heathkit IM−2400 brings quality to hand-held frequency counters - take it
wherever you need to know the value of a frequency."
Uses 5 nickel-cadmium batteries (included) and line current with available
Batteries are housed inside the counter to provide TRUE portability
Wide 50 Hz to 512 MHz frequency range
See full description and video below
Heathkit products were well known for the completeness of its instruction manuals,
with clearly illustrated instructions. During the writing and editing process, Heathkit
employees were given pre-production kits to take home and build, while annotating
any difficulties or errors encountered. Doing so helped minimize the situation where
the writer inadvertently assumes his own familiarity with the process is shared
by the customer. Having built a few Heathkit products myself in the 1970s when I
did not have a lot of experience with electronics assembly, I can attest to the
user friendliness of the instructions.
still sells many of its vintage manuals for around $15, which is what you would
pay on eBay.
Heathkit IM-2400 512 MHz Frequency Counter Kit Parts (eBay
Heathkit IM-2400 512 MHz Frequency Counter Assembled (eBay
Heathkit IM-2400 512 MHz Frequency Counter Schematic
"In this video, I introduce a unique piece of vintage electronic test equipment,
the Heathkit IM−2400 Handheld 512 MHz Frequency Counter, which was introduced
in 1980 and remained in the Heathkit catalog for 10 years. Unlike the various Heathkit
bench frequency counters, this model is optimized for radio work, as it is only
capable of displaying the tested frequency in MHz (even though it can test frequencies
down to 50Hz). I cover the unit's history and features, show the unit inside and
out, demonstrate its operation, go through the user's manual, and finally present
a detailed 'theory of operation' while going through the schematic diagram." -
Modern engineering and sub-miniaturization bring you the first
hand-held Heathkit Frequency Counter - the IM−2400. The most compact Heathkit Frequency
Counter ever combines in-the-field versatility with bench-standard accuracy. Use
the IM−2400 in cars, trucks, aircraft, boats - anywhere you need an accurate frequency
reading. Communications service technicians and Amateur Radio enthusiasts will find
it ideal for servicing mobile radio equipment.
The IM−2400 measures frequencies from a large portion of the
radio spectrum from 50 hertz to 512 megahertz, in two ranges. Accuracy and long-term
stability are assured with a crystal-controlled 10 megahertz time base, The excellent
typical sensitivity of 10 millivolts, RMS (as well as the guaranteed sensitivity
of 25 millivolts, RMS) over the entire range of the IM−2400 means you'll be able
to read weak signals, too. Measure frequency by connecting the IM−2400 directly
to the component under test. Or, for counting without any connections, use the optional
SMA−2400−1 Swiveling Telescopic Antenna (described below). Full voltage protection
is built into the IM−2400 Counter for worry-free operation.
The big, 7−digit LED display is easy to read and gives you better
resolution. Automatic decimal placement and zero blanking assure mistake-free readings.
You get true portability with the Heathkit IM−2400 Hand-Held Frequency Counter.
The batteries are located INSIDE the housing. There are no external battery packs
to make handling the IM-2400 awkward.
Five rechargeable 1.2 volts DG, AA-size nickel-cadmium batteries
are included with this frequency counter - making the IM−2400 an even better value.
You'll be able to use these batteries over and over - up to hundreds of charges
on the same set of batteries - to save on battery replacement costs. And use line
current - and recharge the batteries at the same time - with the available battery
eliminator/chargers below (PS−2404 for 120 VAC, PS−2405 for 240 VAC (one required
for proper operation).
For bench use, the IM−2400 includes a pivoting stand which supports
the counter at a more convenient viewing angle. Find out how portable a frequency
counter can really be. Order the IM•2400 Hand-Held Frequency Counter today.
SM−2400. Factory assembled and tested, Wt. 2 lbs. ................. 179.95
Swiveling Telescopic Antenna for IM−2400, IM−2410 Counters.
Also use on many 2-meter transceivers. Chrome-plated brass antenna provides significant
improvements in performance over similar antennas. Enhance counter sensitivity by
tuning the antenna to the proper frequency - by extending or retracting the telescoping
sections. Right angle version, with BNC connector included.
Inputs: Frequency Ranges: 50 hertz to 50 megahertz, and 40 megahertz to 512 megahertz.
Sensitivity: 50 hertz to 50 megahertz range - 25 millivolts, Root Mean Square (RMS)
guaranteed, 10 millivolts RMS typical; 40 megahertz to 512 megahertz range - 25
millivolts RMS guaranteed, 10 millivolts RMS typical. Input impedance: 50 hertz
to 50 megahertz range -1 megohm shunted by less than 24 picofarads.; 40 megahertz
to 512 megahertz range - 50 ohms. Input Protection: 50 hertz to 50 megahertz range
-150 volts RMS to 100 kilohertz, derating to 10 volts RMS at 50 megahertz; 40 megahertz
to 512 megahertz range - 5 volts RMS. Time Base: Frequency: 10 megahertz. Setability:
+1 part per million (ppm). Temperature Stability: +10 parts per million (ppm), from
0 degrees C to 40 degrees C. General: Gate Time: 1 second or 0.1 second [switch-selectable).
Resolution: 50 hertz to 50 megahertz range - 100 hertz with time base set at 1.0
second, 100 hertz with time base set at 0.1 second; 40 megahertz to 512 megahertz
range - 100 hertz with time base set at 1.0 second, 1 kilohertz with time base set
at 0.1 second. Power Requirement: Five 1.2 volts DC, AA−size rechargeable nickel-cadmium
batteries, 120 volts AC with optional PS−2404 Battery Eliminator/Charger; 240 volts
AC with optional PS−2405 Battery Eliminator/Charger. Overall Dimensions: 1.63 inches
H x 3.38 inches W x 8.38 inches L (4.1 x 8.6 x 21.3 cm). Net Weight: 0.81 pound
(0.37 kilogram), including five AA−size nickel-cadmium batteries.
Heath Company (Heathkit) Operations: PO Box 15, Ottsville, PA 18942 R&D/Mfg:
PO Box 3115, Santa Cruz CA 95063 Phone: +1 (831) 480-4368 E-Mail:
Posted June 8, 2021
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