A bias tee for DC voltage with PTT TX OFF

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98.01 € (tax incl.)
98.01 €
81.00 € (without tax)
  • PL
in stock, shipped in 2-3 days

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The lowest price in the 30 last days was 98.01 €

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This is a special Bias Tee BOX designed to feed an active antenna, amplifier, switch or other device in the RX path via coax. In addition to the classic Bias Tee, it contains additional circuitry such as a 50kHz HPF to eliminate AC noise, an adjustable attenuator (the ability to reduce the signal strength from the amplifier), current and voltage protection on the RF signal, and most importantly, the ability to switch off during TX.

In many cases you will need to power an active antenna or RX amplifier located close to the TX antenna. A strong signal from the transmitter can damage this amplifier or the receiver behind it.

For this reason, the Bias Tee BOX PLUS includes the ability to connect a PTT signal, which will both cut off the DC power to the coaxial cable and short it to ground, thus protecting the receiving equipment.

This box can also be operated without output voltage on the coax - just as short circuit protection when transmitting and disconnecting the cable from the receiver.

The PTT input signal is optically isolated, and the box also includes a PTT OUT, which can be used to avoid losing a PTT signal from a TRX, for example.


  • Providing an RF signal and (DC) power to a remote device over one coax
  • Switching DC and RF signal while transmitting
  • You can use bias tee on both sides as DC IN and OUT from RF coax
  • For preamplifier or Bi-dir beverage

Main functions

  • Broadband: 0.1 MHz to 60 MHz
  • High Pass Filter 50 kHz (AC noise filter)
  • Variable ATTENUATOR - settings
  • Front-end protection with diodes - settings
  • Bias Tee DC voltage 12 or 24V - settings
  • Bias Tee DC current 0.5A
  • DC short protection about 1A
  • Power supply common-mode filter
  • High voltage and current protections
  • LED diode indication of DC OUT and PTT TX
  • PTT IN with optocoupler
  • PTT OUT with 0.5A FET
  • You can set ATT when you have too high gain of preamp
  • Quality connectors
  • IP56 box - recommended to protect it against water
  • Feeder size 100x100 mm


  • Supply voltage DC 12 V or 24 V
  • Voltage range for 12 V: 11 to 14.5 V
  • Voltage range for 24 V: 22 to 26 V
  • DC current 0.5A
  • DC out Jumper - could be OFF
  • Frequency range 0.1 MHz to 60 MHz
  • HPF 50 kHz ( > 40 dB @ 10 kHz, 3 dB @ 70 kHz)
  • Output RF diode limiter
  • High RF voltage and current protection (90 V, 200 mA)
  • PTT IN transmitting = connecting to GND
  • PTT IN current typ. 6/11 mA
  • Insertion loss lower than 0.8 dB
  • Isolation (PTT TX) > 80 dB @ 28 MHz
  • LED shows DC out - GREEN
  • LED shows PTT active - RED

Available as

ASSEMBLED: ready to use

Included in package

Bias Tee BOX PLUS assembled and tested


If you want to know more please check our wiki with Bias Tee Box PLUS manual.

The PTT circuit only works when power is applied. PTT OUT does not work without power.

bias tee box plus pl so-239 connector qro.cz hamparts.shop

bias tee box plus pl so-239 block diagram qro.cz hamparts.shop

Insertion loss and SWR - RF limiter OFF

bias tee box plus pl so-239 measurement qro.cz hamparts.shop

Insertion loss and SWR - RF limiter ON

bias tee box plus pl so-239 measurement qro.cz hamparts.shop

Isolation when PTT is active

bias tee box plus pl so-239 measurement qro.cz hamparts.shop

recommendations to buy rx audite sdr splitter switch by qro.cz hamparts.shop

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Product Details

Data sheet

in enclosure
both 50 & 75 Ohm
front-end protection
frequency range
0.1 MHz to 60 MHz
product dimensions
100x100x50 mm - PU box IP56
PCB dimensions
95x95 mm
product weight (brutto)
0.33 kg
package dimensions
18.5x14x10.5 cm

Specific References

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