Click for homepage
Sadelco FS-3
Field strength meter

FS-3 was a field strength meter, also known as a signal level meter (SLM), developed and built by Sadelco in Weehawken (New Jersey, USA) in the mid-1970s [1]. The meter was used for several decades by radio and television engineers for adjusting antennas and measuring signal strength in TV and CATV 1 installations. The meters were also used for locating clandestine transmitters.

The FS-3 is housed in a sturdy metal enclosure and measures 20 x 12 x 8 cm. It is usually stored in a leather carrying case from within which it can be operated. The device is fully self-contained, with only the antenna connected externally. Power is provided by internal 9V batteries, or by an external AC mains adapter.

The FS-3 is suitable for the reception of AM and FM signals, and has two tuners that are referred to as the LOW and HIGH band tuners. The actual frequency range is determined by the model number. The unit shown here is the FS-3CE.
Sadelco FS-3CE in leather carrying case

It is suitable for 47-230 MHz (VHF) and 470-860 MHz (UHF) and has a separate tuning knob for each tuner. The audio from the intercepted signal can be demodulated and monitored via a small built-in speaker. One 6dB and three 20dB attenuators can be inserted in the antenna path, which can be useful when handling strong signals, or when operating it in close proximity of a station.

In the Netherlands, the FS-3CE was used heavily during the 1970s and 80s by the Dutch Radio Monitoring Service (RCD), when the country was flooded by illegal CB stations 2 (27 MHz) and by so-called radio pirates, operating music stations in the VHF FM broadcast band (100-108 MHz).

The FS-3CE was sometimes used as a portable unit, but was also used as part of the complete intercept and direction finding (DF) installation shown in the image on the right. In this case, the installation is housed in a small 19" rack, with the FS-3SE clearly visible at the bottom left [5].
Intercept vehicle of the Dutch RCD in the late 1970s. Click for more information.

The 19" rack was placed on the passenger seat of the intercept vehicle, in such a position that it could be operated easily by the driver, who was also the law-enforcement officer. For a detailed description of the remaining equipment in the rack, please refer to our page about the RCD.

FS-3 meters are still popular today and can occasionally be found on auction sites such as eBay. They are most useful for locating the source of local interference and can still be used to locate a clandestine radio station (pirate). In the mid-1980s, the FS-3 range was succeeded by the FS-4.

  1. CATV = Community Access Television, or Community Antenna Television. CATV has since become synonymous with Cable Television  Wikipedia
  2. At that time, the use of the Citizen's Band was still illegal in the Netherlands.

FS-3 in black leather carrying case
Sadelco FS-3CE in leather carrying case
Sadelco FS-3 in case - front view
Open case
Front panel
Rear panel with instructions and battery compartment
large accurate meter
All controls and connections of the FS-3CE are at the control panel, and can be accessed without removing the device from its black leather carrying case. The unit is powered by four 9V block batteries that are installed at the rear, or alternatively by an external AC mains adapter that can be connected to one of the sockets on the control panel. The unit is turned ON with the switch at the top left. An antenna should be connected to the 75Ω PL-259 socket 1 at the bottom right.

Click to see more

To the left of the antenna socket are four black switches, each of which represents an attenuator. There are three 20dB attenuators an one that does just 6dB. The red switch at the center is used to select between the HIGH and LOW tuner, each of which has its own frequency dial.

  1. Some units were fitted with BNC socket at this position.

Model Low tuner High tuner Remark
FS-3 ? ?  
FS-3C 54-216 MHz 470-812 MHz VHF & UHF
FS-3SC 54-216 MHz 216-300 MHz VHF & Super Band
FS-3CE 47-230 MHz 470-860 MHz European variant
FS-3D ? ?  
About Sadelco
Sadelco was founded in 1960 by Harry Sadel and became well-known for its development and production of field strength meters, later also known as CATV signal level meters or SLM. The line started around 1961 with the FS-1, which was soon followed by the FS-2 and several years later by the immensly popular FS-3 series. The FS-3 was available for many years in quite a few variations. It was eventually succeeded by the FS-4 and later by digital alternatives.

Company founder Harry Sadel was born on 6 September 1920 and started his business in Canada during the 1950s. In 1960, he moved to the United States, where he founded Sadelco. In 1985, on the 25th anniversary of the company, it was announced that his son Joe Elliot (Joey) was to become director of R&D at Sadelco. He would later become vice-president of the company [4].

Harry Sadel passed away on 11 October 2002 at the age of 82. After 54 years in business, the company closed its doors in 2014. Warranty and service of existing equipment and parts is taken over by RCB Calibration LLC, a company run by former Sadelco employee Rob Bredin. [3]

Last known addresses
  • Sadelco
    75 W. Forest Ave.
    Englewood, NJ 07631
    United States
    Phone: 2015693323

  • Registered address
    96 Linwood Plz
    Fort Lee, NJ 07024
    United States

  • RCB Calibration LLC
    Continued support for Sadelco meters
    Phone: +1 800-569-6299
ADF   Automatic Direction Finder
AM   Amplitude Modulation
CATV   Community Access Television
Also used as abbreviation for Community Antenna Television, and later as a common expression for Cable Television.
FM   Frequency Modulation
FS   Field Strength
RCD   Radio Controle Dienst
Radio Monitoring Service in the Netherlands. Currently known as AT.
RDF   Radio Direction Finder
SLM   Signal Level Meter
UHF   Ultra High Frequency
VHF   Verhy High Frequency
  1. Anonymous, Sadelco FS-3CE field strength meter - THANKS !
    Received April 2010. #CM-30881-DF.

  2. The Old CATV Equipment Museum, Signal Level Meters
    Retrieved December 2016.

  3. RCB Calibration LLC, About
    Retrieved December 2016.

  4. Joey Sadel, Sadelco R&D California (TM)
    Retrieved December 2016.

  5. Unknown source, Photograph of RCD intercept vehicle
    Date unknown, but probably mid to late 1970s.
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Created: Monday 12 December 2016. Last changed: Friday, 16 August 2019 - 08:49 CET.
Click for homepage