KeL-fil® Product Information

KeL-fil ImageThis page is intended as a supplement to the product entry for the KeL-fil® line of ceramic (dielectric resonator) filter products. The tables below contain Product Notes and information on Part Numbering, PCB Layout, and Reflow Profile.

KeL-fil® brand ceramic bandpass filters are 2 to 6 section designs ranging in frequency from 270 MHz to 3000 MHz providing users with low-cost filter solutions ideally suited for wireless applications. These designs are featured in Filter Wizard®.

Electrical performance and mechanical dimensions provided by Filter Wizard®.

Filter Characteristics

Center Frequency 270 to 3000 MHz *See Note 1
Filter Type Chebyshev Bandpass *See Note 2
Number of Sections 2 to 6  
Bandwidth Up to 30% (dependent on f0, Er, and resonator profile) *See Note 3
Attenuation Guaranteed to -60 dBc (270 to 2000 MHz)
Guaranteed to -30 dBc (2001 to 3000 MHz)
*See Note 4
VSWR 2.0:1 maximum  
Temperature Range -40 to +85°C Operating
-50 to +125°C Storage
Temperature Stability +2 to +11 ppm/°C *See Note 5
Package Style Surface Mount and Drop-in Configurations *See Note 5

Environmental Capability

Vibration MIL-STD-202, 204A
Shock MIL-STD-202, 213A
Humidity MIL-STD-202, 103B
Thermal Shock MIL-STD-202, 107A
Solderability MIL-STD-202, , Method 208

Note: MIL-STD used for reference purposes only

Installation Notes

    • When handling KeL-fil products, avoid touching any solderable surface with bare hands or other contaminants as solderability may be reduced.
    • Ceramic filters are made of very durable materials. However, mishandling of the product (especially RF leads) will damage the device. Avoid forcing the product into place by any means.
    • KeL-fil products can be cleaned via solvent- based, aqueous, semi-aqueous, and alcohol- based systems. Be sure to completely dry the units; any entrapped moisture will cause erroneous electrical performance.
    • A typical reflow profile is provided above. When establishing a reflow procedure, be sure to consider the higher relative mass of ceramic components, as the units will take longer to achieve reflow temperatures.
    • Take special care to ensure the input trace is not smaller than the RF trace on the filter. This will eliminate an impedance mismatch which would cause the filter to appear to have a high ripple content.
    • All K&L Microwave ceramic filters are assembled using SN96 high temperature solder. K&L recommends that customers use SN60 or SN63, or an equivalent, during installation for signal and ground connections.
    • The rate of heating and cooling must be controlled to preclude thermal cracking of the devices. Processes, heating or cooling, should not exceed a rate of 200°C per minute. Spikes must not exceed 100°C maximum for any solder operation. Avoid forced cooling or contact with heat sinks, such as conveyor belts, metal tables or cleaning solutions, before the units reach ambient temperatures.
    • Recommended procedure for hand soldering (Not recommended for Series 5 packages):

  1. Equipment: Weller Ec-2001 soldering system (42 Watt) or equivalent (1/8" tip) 260 +/- 10°C tip temperature
  2. Solder: SN60 / SN62 / SN63
  3. Flux: Kester 1544 type RMA or equivalent
  4. Cleaning Solvent: Commercial defluxing solvent

Product Notes

Note 1 Center frequencies from 3 to 5.8 GHz are available by request.
Note 2 Bandreject and multiplexed filters are available by request.
Note 3 Custom packaging available by request.
Note 4 Maximum bandwidth is dependent on center frequency, the dielectric constant of the resonator and the resonator profile.
Note 5 For f0 < 2000 MHz, attenuation levels are guaranteed to -60 dBc. Values given are theoretical at levels > -60 dBc.
For f0 > 2000 MHz, attenuation levels are guaranteed to -30 dBc. Values given are theoretical at levels > -30 dBc.
Note 6 Ultimate rejection may be affected by: 3rd harmonic, Hybrid modes in coaxial resonator, Finite isolation properties of packaging (shielding)
Note 7 Due to manufacturing variations, please observe these guidelines:
  • Actual attenuation at any given frequency point may vary by +10%.
  • Actual 3 dB bandwidth may be wider than specified (typically 10-20%).
  • Passband insertion loss may exceed given value (10% maximum)

Product Information

Part Numbering
Product Numbering
1. Number of Sections
2. DL = Dielectric Resonator Bandpass (Er = 22)
DR = Dielectric Resonator Bandpass (Er = 37)
DH = Dielectric Resonator Bandpass (Er = 90)
3. Resonator Size
2 = 4mm
3 = 6mm
4. Mounting / Case Style
1 = PCB Through-hole
3 = SMD Tab
5 = SMD Leadless (Series 5)
5. Center Frequency in MHz
6. Supplemental Codes
H = 0.5 dB Bandwidth
U = 1 dB Bandwidth
T = 3 dB Bandwidth
7. Bandwidth in MHz
8. Software Version Number

Outline Drawings

See Filter Wizard for:

  • Leadless Surface Mount - Series 5
  • Surface Mounting - Tab
  • Drop-in (PC) Mounting
Recommended PCB Layout
DR 25, 35 Series depicted / .xxx= Dim.A / .yyy= Dim.B
DR 23,33 Series depicted / .xxx=Dim. A / .yyy=Dim. B
Typical Reflow Profile for Non-RoHS KeL-fil Filters
Reflow Diagram
Typical Reflow Profile for KeL-fil RoHS Compliant Filters
Reflow Diagram