Product Description
DCI Passband Filter – 420.75-426.50 MHz, Narrowband RF Filter for Critical Communications
This used DCI (Microwave) passband filter is a precision RF component designed to pass signals in the 420.75-426.50 MHz frequency range while attenuating out-of-band signals. With approximately 5.75 MHz bandwidth, this filter provides excellent selectivity for critical communications applications.
DCI Microwave was a respected manufacturer of high-quality RF and microwave components, including filters, couplers, and other passive devices for communications, defense, and test applications.
Frequency Band Applications
The 420.75-426.50 MHz passband covers specific segments with important applications:
| Band/Service | Frequency Range | Application |
|---|---|---|
| 70cm Amateur Radio | 420-430 MHz | Weak signal, EME (moonbounce), satellite uplinks |
| Government Radiolocation | 420-450 MHz | PAVE PAWS, military radar, critical infrastructure |
| Federal Agencies | Various | Law enforcement, emergency services |
| Military Communications | 420-450 MHz | Tactical and fixed communications |
| Auxiliary Broadcasting | 420-430 MHz | Broadcast relay (part 74) |
This filter is ideal for:
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Critical communications systems requiring precise frequency control
-
Amateur EME (moonbounce) and weak signal work
-
Government/military installations needing clean spectrum
-
Radar system protection from out-of-band interference
-
Test setups requiring precise frequency selection
Key Specifications
| Specification | Details |
|---|---|
| Manufacturer | DCI Microwave (Microwave Development Company) |
| Type | Passband filter (bandpass) |
| Passband | 420.75 – 426.50 MHz |
| Bandwidth | ~5.75 MHz |
| Center Frequency | ~423.6 MHz |
| Impedance | 50 ohms (typical) |
| Connectors | [Likely SMA, N-Type, or BNC – inspect] |
| Insertion Loss | [Low in passband] |
| Rejection | [High out-of-band] |
| VSWR | [Low in passband] |
| Power Handling | [If known, watts] |
Critical Applications Note
The 420-430 MHz band is designated for government radiolocation in the US, including the PAVE PAWS radar system for missile warning and space surveillance. Filters in this band must meet stringent requirements for:
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High power handling (radar systems)
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Low insertion loss (preserving signal strength)
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Excellent rejection (protecting sensitive receivers)
-
Environmental stability (temperature, humidity, vibration)
Applications
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Government/Military Communications: Secure and critical voice/data links
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Radar Systems: Protecting receivers from out-of-band interference
-
Amateur Radio: 70cm weak signal (CW/SSB), EME (moonbounce)
-
Satellite Uplinks: 70cm amateur satellite uplink filtering
-
Test & Measurement: Harmonic and spurious rejection
-
Receiver Front-End: Preventing out-of-band interference
-
Transmitter Output: Cleaning up transmitted spectrum
Condition
SOLD AS IS
USED – SHOWS NORMAL WEAR (scuffs, minor marks)
RF PERFORMANCE NOT TESTED
NO MOUNTING HARDWARE OR DOCUMENTATION INCLUDED
PICTURE MAY NOT MATCH PRODUCT
| Weight | 35.2 lbs |
|---|---|
| Dimensions | 24 × 16 × 12 in |
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