5-Inch 6-Cavity VHF Duplexer (BPBR)

136-175 MHz, 250 W, > 80 dB Tx noise suppression, 1.8 dB IL @ 500 kHz separation. 4 BR + 2 BP cavities.

Frequency

136–175 MHz
Power

25 W
Isolation

> 8 dB
Insertion loss

< 1.8 dB
Connector

N-Female
Weight

18 kg

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Specifications

Electrical

Frequency range	136–175 MHz
Power handling	25 W
Insertion loss	<1.8 dB
Tx-Rx isolation	>8 dB
VSWR (max)	1.5
Impedance	5 Ω

Mechanical

RF connectors	N-Female
Weight	18 kg
Dimensions (H × W × D)	850 × 445 × 275 mm

Configuration

Cavity Count	6
Cavity Topology	4 BR + 2 BP
Cavity Diameter Inch	5
Separation Min Khz	500
Frequency Stability	0.8 ppm/°C
Temperature Range	-30°C to +60°C
Mounting	19-inch rack

Verified 2026-05-06 · ALUNOR RF Engineering · source: ALUNOR RF Technical Catalogue 2026-01-21

All measurements at 25 °C, 50 Ω, unless otherwise noted.

Why this product

01

BPBR topology — 4 BR + 2 BP cavities deliver > 80 dB suppression at 1.8 dB IL
02

5-inch cavities for compact 18 kg / 850 mm chassis
03

Field-tunable across the entire 136-175 MHz band

Technical brief

Construction

Four band-reject cavities tuned to suppress the opposite carrier, plus two band-pass cavities tuned to the operating carrier — the classic BPBR topology. The result: > 80 dB of suppression of the unwanted carrier with 1.8 dB maximum insertion loss at 500 kHz Tx-Rx separation.

Where this fits

VHF voice repeater installations with Tx-Rx separation around 500 kHz to a few MHz where chassis depth (only 850 mm) and weight (18 kg) matter. The 5-inch cavity is a balance of selectivity and footprint — heavier deployments step up to the 6-inch or 8-inch variants.

Tuning

Field-tunable across 136-175 MHz with a service monitor and a 1/4" hex driver. Factory tuning is available — specify your Tx/Rx pair on the order form.