HF SDR FEM

1.8 – 30 MHz (extendable to 70 MHz)

50 W on HF — antenna tuning built in (extendable to 100 W with external PA).

ApplicationsHF 2G/3G ALEMIL-STD-188-141 B/C/DWideband HF 4G ALEPACTORFT8

Key Specifications

RF Frequency Range: 1.8 – 30 MHz (extendable to 70 MHz)
Fixed IF: 390 MHz
IF Bandwidth Options: 1.1 MHz, 8 MHz, 20 MHz
Tx Gain: +20 dB typ. (no PA) / +70 dB (with PA)
Rx Gain: +20 dB typ.
Tuneable Gain: 20 dB (1 dB step)
Nominal Input Power: −23 dBm
Max Output Power: +47 dBm (50 W, internal PA)
External PA: Up to 100 W
Harmonics Rejection: Min 50 dBc (2nd / 3rd)
Spurs Rejection: Min 45 dBc
VSWR Protection: 2:1 max
Coupler Dynamic Range: 20 dB (+30 to +50 dBm)

Module

Exploded view — 4-board PCB stack

Ruggedised enclosure — QSR-HF-FEM-EC

Signal chain

Full Tx/Rx path from SDR through power, filtering, and antenna interface.

Section 1 — SDR side

Section 2 — PA + ATU + Filter Bank

The boards

4 boards in the HF chain

Individual boards ship as bare PCBs (Open Card). The full series ships as one ruggedised, enclosed assembly — QSR-HF-FEM-EC.

B1 — Up/Down Converter

SDR-side IF/RF conversion with filter banks and gain control

Section 1 SDR-side board. Bidirectional up/down conversion between the SDR's IF and the 1.8 – 30 MHz RF band. Includes an IF gain block, digital step attenuator (DSA), IF SAW filter bank, RF LNA, LPF + notch filtering, LO synthesizer, mixer, and bypass switches for path selection.

Key blocks

IF Gain Block
Digital Step Attenuator (DSA)
IF SAW Filter Bank (3 bands)
RF LNA
LPF + Notch Filters
LO Synthesizer
Mixer
Bypass Switches

QSR-HF-B1-OCopen card

B2 — 50 W Power Amplifier

Internal Tx amplification stage

Solid-state 50 W power amplifier driving the HF Tx chain. Built around a driver amp, RF gain block, and the main PA stage. Designed for sustained duty cycle operation with thermal management for ruggedised enclosures.

Key blocks

RF Gain Block
Driver Amplifier
50 W Power Amplifier

QSR-HF-B2-OCopen card

B3 — Antenna Tuning Unit (ATU)

Automatic impedance matching to real-world HF antennas

Antenna Tuning Unit with SPnT switches, T/R switch, coupler, and limiter. Matches the PA output to whatever antenna the radio is talking to — whippers, dipoles, wire antennas — so operators don't lose power to mismatch.

Key blocks

SPnT Switches
T/R Switch
Directional Coupler
Limiter
Matching Circuits

QSR-HF-B3-OCopen card

B4 — Harmonic Filter Bank + T/R Switch

Final-stage harmonic rejection and Tx/Rx routing

Switchable LPF filter bank for harmonic rejection on the PA output, plus the high-power T/R switch that routes between transmit (after the PA) and receive (to the LNA chain). Ensures clean spectrum and protects the receiver from transmitter leakage.

Key blocks

LPF Filter Bank
T/R Switch
Limiter

QSR-HF-B4-OCopen card

Open-card kits and ruggedised enclosed assemblies for the full HF family.

Ordering

HF ordering options

Order individual boards as bare PCBs (Open Card), or the full series as a ruggedised enclosed assembly. Contact us for exact lead times.

Item	Form factor	SKU	Action
B1 SDR-side IF/RF conversion with filter banks and gain control	Open Card (OC)	QSR-HF-B1-OC	Enquire
B2 Internal Tx amplification stage	Open Card (OC)	QSR-HF-B2-OC	Enquire
B3 Automatic impedance matching to real-world HF antennas	Open Card (OC)	QSR-HF-B3-OC	Enquire
B4 Final-stage harmonic rejection and Tx/Rx routing	Open Card (OC)	QSR-HF-B4-OC	Enquire
Full series (FEM) All 4 boards	Enclosed (EC)	QSR-HF-FEM-EC	Enquire

OC — individual boards as bare PCBs

EC — full series, ruggedised cased assembly

Enquire about the HF series

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