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RT/RTR & RJ/RJR Information

Specifications

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RT/RTR Part Number Breakdown

RJ/RJR Part Number Breakdown

RJ/RJR

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RT/RTR & RJ/RJR Terminals

RT/RTR

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RJ/RJR

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How do Trimmer Potentiometers Work?

Trimmer Potentiometers or “Trim Pots” as they are often called are basically miniature three terminal variable resistors (potentiometers). Trim pots work on the same principle as potentiometers. Trim pots have three terminals two of which are connected to a resistive strip or resistive track, the third is connected to an adjustable wiper. The position of the wiper on the resistive track determines the output voltage (as shown in the diagram). The material that’s used for the resistive element typically is made out of a carbon composition(Wirewound) or cermet. Usually trim pots are installed onto PCB’s (Printed Circuit Board) for fine tuning, (re)calibration, or any other type of adjustments in a circuit. When trim pots are used as replacements for regular potentiometers, adjustments should only be done when it’s absolutely necessary. Due to their size trim pots are very fragile, and most manufactures rate their lifespan at 200 cycles so frequent adjustments are not recommended. This rating applies to both Mil-Spec and commercial variants of trim pots.

trimpot diagram

RT/RTR & RJ/RJR Series Trim Pots

RT/RTR and RJ/RJR series trim pots are made to military specifications and are listed on the QPL (Qualified Parts List). Which simply means that they are on a government approved list of parts that are approved for government and military use. RT/RJ series trim pots are made to the MIL-PRF-22097 and the RTR/RJR series trim pots are made to the MIL-PRF-39035. The major difference between RT/RJ and the RTR/RJR series is that the RTR/RJR trim pots are offered with a failure rate. A failure rate is the frequency at which a component fails during testing over a set period of time. RTR/RJR series of trim pots are offered in three failure rate levels:

Note: Failure per 1000 hours of testing

  • M = 1.0%
  • P = 0.1%
  • R = 0.01%

Although the RJ/RJR series and the RT/RTR series look pretty much identical, they have two different restive elements used for the resistive track that the wiper follows.

  • RT/RTR = Wirewound
  • RJ/RJR = Cermet

Please note that we at Federal Connectors recommend the RJ/RJR series trim pots over the RT/RTR series trim pots. Due to the RT/RTR series slowly becoming obsolete, there has been an increase in price of trim pots in that series. Another factor to take in consideration is longer lead times for trim pots that are out of stock from the RT/RTR series.

All the series of trim pots mentioned above are a sealed style trim pot, which means that the resistive track and the wiper are covered by a protective material. These trim pots are available in a wide variety of resistance ranges. Depending on the series, these trim pots they may either have a temperature rating of -55°C to 150°C or -65°C to +150°C. Since trim pots are designed for making small adjustments to electrical circuits and are usually mounted to a PCB (Printed Circuit Board), they relatively have a low rotational life. Both the RT/RTR and the RJ/RJR series of trim pots are rated at 200 cycles (For more info take a look at the spec. tables below). Differentiating between manufactures is relatively easy, Bourns trim pots are blue in color and VRN trim pots are green (As shown in the images below).

Bourns Trim Pot

RT12 - Bourns

VRN Trim Pot

RT12 - VRN

RT/RTR Specifications
SeriesMil-PrefPower RatingSize (in")Standard Resistance RangeAbsoulute Minimum ResistanceTemp. RangeAdjustment TravelTorque
RT12MIL-PRF-2720870°C 1 Watt1 1/410 - 20K ohms0.1% or 1ohm max-55°C to +150°C22 turns nominal5.0 oz-in. max
RT22MIL-PRF-2720885°C 0.75 Watt1/2"50 - 20K ohms0.1% or 1ohm max-65°C to +150°C25 turns nominal5.0 oz-in. max
RTR22MIL-PRF-3901585°C 0.75 Watt1/2"500 - 20K ohms0.1% or 1ohm max-65°C to +150°C25 turns nominal5.0 oz-in. max
RT24MIL-PRF-2720885°C 0.25 Watt3/8"10 - 10K ohms0.1% or 1ohm max-65°C to +150°C25 turns nominal5.0 oz-in. max
RTR24MIL-PRF-3901585°C 0.25 Watt3/8"500 - 10K ohms0.1% or 1ohm max-65°C to +150°C25 turns nominal5.0 oz-in. max
RT26MIL-PRF-2720885°C 0.25 Watt1/4"10 - 5K ohms0.25% or 1ohm max-55°C to +150°C11 turns nominal3.0 oz-in. max
RJ/RJR Specifications
SeriesMil-PrefPower RatingSize (in")Standard Resistance RangeAbsoulute Minimum ResistanceTemp. RangeAdjustment TravelTorque
RJ12MIL-PRF-2209770°C 1 Watt1 1/410 ohms - 1 megohm1% or 2ohms max-55°C to +150°C22 turns nominal5.0 oz-in. max
RJ22MIL-PRF-2209785°C 0.25 Watt1/2"10 ohms - 1 megohm1ohm max-65°C to +150°C25 turns nominal5.0 oz-in. max
RJ24MIL-PRF-2209785°C 0.50 Watt3/8"10 ohms - 1 megohm2% or 20ohms max-55°C to +150°C25 turns nominal5.0 oz-in. max
RJR24MIL-PRF-3903585°C 0.50 Watt3/8"10 ohms - 1 megohm2% or 2ohms max-55°C to +150°C25 turns nominal5.0 oz-in. max
RJ26MIL-PRF-2209785°C 0.25 Watt1/4"10 - 1 megohm2% or 20ohm max-65°C to +150°C12 turns nominal3.0 oz-in. max
RJR26MIL-PRF-3903585°C 0.25 Watt1/4"10 - 1 megohms2% or 2ohms max-65°C to +150°C12 turns nominal3.0 oz-in. max
RJ50MIL-PRF-2720885°C 0.50 Watt1/4"10 - 1 megohms1% or 2ohms max-55°C to +150°C1 turn (240°) nominal5.0 oz-in. max
RJR50MIL-PRF-3903585°C 0.50 Watt1/4"10 - 1 megohms1% or 2ohms max-55°C to +150°C1 turn (240°) nominal5.0 oz-in. max

Part Number Breakdown for RT Style Trim Pots

Example: RT12 C2 P 101

RT12C2P101
||||
ModelCharacteristicTerminal StyleResistance Code
1234

1. Model

  • RT12
  • RT22
  • RT24
  • RT26

2. Characteristic

  • C = ±50ppm/C° Temp. Coeff. Max.
    2 = 85°C - 150°C Operating Temp.

4. Resistance Code

resistance code table

Part Number Breakdown for RTR Style Trim Pots

Example: RTR24 D P 202 M

RTR24DP202M
|||||
ModelCharacteristicTerminal StyleResistance CodeFailure Rate
12345

1. Model

  • RTR22
  • RTR24

2. Characteristic

  • D = ±50ppm/C° Temp. Coeff. Max.

4. Resistance Code

resistance code table rtr22

5. Failure Rate

  • M = 1.0%
  • P = 0.1%
  • R = 0.01%
 

Terminal Styles for RT/RTR Trim Pots

RT12

RT/RTR22

RT/RTR24

RT26

Part Number Breakdown for RJ/RJR Style Trim Pots

Example: RJR24 F W 502 R

RJR24FW502R
|||||
ModelCharacteristicTerminal StyleResistance CodeFailure Rate
12345

1. Model

  • RJ12
  • RJ22
  • RJR24
  • RJ24
  • RJ26
  • RJR26
  • RJ50
  • RJR50

2. Characteristic

  • F= ±100 ppm/°C Temp. Coeff. Max.

4. Resistance Code

Resistance Table RJ/RJR

5. Failure Rate

  • M = 1.0%
  • P = 0.1%
  • R = 0.01%
 

Note: failure rate only applies to RJR Part Numbers.

Terminal Styles for RJ/RJR Trim Pots

RJ12

RJ22

RJ/RJR24

RJ/RJR26

RJ/RJR50

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Federal Connectors is a supplier of Military Connectors, Military Fuses, Military Potentiometers, Military Resistors, Military Relays and other electronic components to the US government and various subcontractors. Our team at Federal Connectors has been serving government agencies and industrial organizations throughout the electronics community for over 25 years. We provide our customers with an easy shopping experience and reliable fulfillment.

Datasheets and Resources

Federal Connectors not only provides our customers with great products at exceptional prices. We also offer our customers access to our vast library of resources, which includes everything from datasheets to technical drawings.

The most recent datasheets and specifications on RJ/RJR and RT/RTR Series Trim Pots can be downloaded by clicking on the pdf icons. Major manufacturers of the RJ/RJR and RT/RTR Series Trim Pots include Bourns and VRN (No longer Manufacturing Trim Pots).

Bourns Trim Pots Datasheets
RT/RTR SeriesRJ/RJR Series
SeriesDatasheetSeriesDatasheet
RT12RJ12
RT22/RTR22RJ22
RT24/RTR24RJ24/RJR24
RT26RJ26/RJR26
  RJ50/RJR50