Non-Inductive High Frequency Melf Resistors (RFM)


Non-Inductance MELF offer greater choice for high frequency applications.

The high frequency RFM speciality series of non-inductance MELF resistor from Direct Electronics has been extended to offer more than GHz operation, making the devices more suitable for high frequency RF applications.

They are the perfect choice in high frequency circuit designs where the parasitic inductance of regular, helical trimmed resistors can not be accepted, but where also pulse energies apply. Typical applications are in the fields of telecommunication equipment and industrial electronics.

These high stability, non-inductance MELF resistors have a footprint very close to comparable chip resistors but maintain their tolerance and deliver higher stability over a wider temperature range. Sizes range from 5.7 x 2.1mm for the RFM74 MELF-0207, through 3.45 x 1.3mm for the RFM73 MELF-0204 down to 2.2 x 1.3mm for the RFM72 MELF-0102.

Production is strictly controlled and follows and extensive set of instructions established for reproducibility. The groove on the metal alloy film of high grade ceramic rod is special designed to achieve non inductance. The resistor elements are covered by a protective coating designed for mechanical, electrical and climatic protection.

The terminations are covered with a final pure tin plating for keeping perfect solderability. Four or five color code rings designate the resistance value and tolerance in accordance with IEC 60062.

Direct's RFM MELF standard series can be a replacement for Vishay, IRC, EBG, KAO, Panasonic Precision Devices with more competitive price and short lead time. Contact us with your specific needs. Download PDF Specification High Frequency Non-Inductance Melf Resistors (RFM).

Features :
  1. Low-inductance non-helical trimmed product.
  2. Ower dissipation rating at 70°C up to 0.75W.
  3. Speciality high frequency product for RF applications.
  4. Suitable for more than GHz operation; Excellent overall stability: Class 0.5.
  5. Tolerance range: ±0.5% to ±5.0%; Resistance range: 25Ω to 200Ω.
  6. Special metal film technology, DIN: 0102, 0204, 0207.
  7. Lead (Pb)-free and RoHS compliant.
Applications :
  1. Medical Equipment.
  2. Industrial electronics.
  3. Automatic Equipment Controller.
  4. HF and pulse loading applications.
  5. Testing & Measurement Equipment.
  6. Consumer Product, Printer Equipment.
  7. Communication Device, Cell phone, GPS, PDA.
Dimensions & Recommended Soldering Bath Dimensions (RFM)
High Frequency MELF Resistor (RFM) Dimensions
High Frequency MELF Resistor (RFM) Dimensions
Recommended Soldering Bath (RFM) Dimensions
Recommended Soldering Bath (RFM) Dimensions
Type RFM72 RFM73 RFM74 RFM75
Metric sizes DIN: 0102 DIN: 0204 DIN: 0207 DIN: 0207
Dimension (Unit: mm) L±0.2 2.2 3.45 5.7 6.0
L1±0.2 1.2 1.6 3.0 3.3
D±0.2 1.3 1.3 2.1 2.1
K±0.1 0.4 0.8 min 1.2 min 1.2 min
D1±0.1 D+0/D-0.15 D+0/D-0.25 D+0/D-0.3 D+0/D-0.3
Recommended Soldering Bath
Dimension (Unit: mm)
S 1.0 1.6 2.6 2.8
W 2.0 2.0 2.5 2.5
H 2.0 2.5 2.5 2.5
Characteristics (RFM)
Type RFM72 RFM73 RFM74 RFM75
Metric sizes DIN: 0102 DIN: 0204 DIN: 0207 DIN: 0207
Resistance range 25Ω ~ 200Ω
Operating Temperature range -55°C ~ 125°C
Resistance Tolerance (%) D(±0.5);   F(±1.0);   J(±5.0)
Temperature coefficient (PPM/°C) C1(±100);   C2(±50);   C3(±25);   C5(±15);   C6(±10)
Rated dissipation (W)   P70 0.125 0.25 0.5 0.75
Operating mode standard standard standard power
Climatic category (LCT/UCT/days) 55/125/56 55/125/56 55/155/56 55/155/56
Endurance, Max, resistance change at P70,
ΔR/R max., after 1000h
≤0.5% for Tol.=±1%   &   ≤1% for Tol.=±5%
Derating standard type linear from 70°C to 125°C
Insulation voltage 500V
Insulation resistance >1GΩ
Order Codes (RFM)
RFM73 100R F C3 TR
Part Number
Resistance Value (Ω)
100R 100Ω
Resistance Tolerance (%)
D ±0.5%
F ±1.0%
J ±5.0%
Temperature coefficient (PPM/°C)
C1 ±100ppm/°C
C2 ±50ppm/°C
C3 ±25ppm/°C
C5 ±15ppm/°C
C6 ±10ppm/°C
P Bulk
TR Taping Reel