EME166 Transverter Sequencer

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EME166 Transverter Sequencer Description:

The EME166 Sequencer replaces the very popular EME66 Kit that has been produced for well over 10 years. The New Kit makes connection to other circuitry much easier due to a single 10 way header connector on the board. The Sequencer can be used to control Transverters with various component like antenna relays, power amplifier, or receive preamplifiers. It is also suitable for sequencing the switching of high power RF amplifiers with a transceiver. The circuitry incorporates both DC and RF sensed inputs that can be used to control the switching of the sequencer from RX to TX mode. The sequencer suits Transverters with either a single, or dual I/F connections. The circuitry uses a PIC micro controller and MosFET switches, and has over voltage and current protection. The 23cm Transverter Block Diagram shows how this Kit can be used.

 

Specifications:

  • I/F TX Input: 28MHz to 500MHz up to 4 Watts maximum
  • TX / RX Delay:  Adjustable Trim pot
  • TX Attenuation:  Adjustable trim pot -14 to -39dB @ 144MHz
  • RX Attenuation:  Adjustable trim pot -0.5 to -10.5dB @ 144MHz
  • Switched Inputs: ( PTT ) +12vdc ( FT290R ), 0vdc to TX ( IC202 ), RF sensed switching also onboard
  • Switched Outputs: Delay1, RX +12v, all TX outputs 0v ( RX Power )
    Delay2, RX 0v, TX +12vdc ( coaxial antenna relay )
    Delay3, RX 0v, TX +12v ( power supply to TX power amplifier )
    Delay4, RX 0v, TX +12v ( TX stages power supply )
  • Power: +8 to +14vdc supply.  Current RX mode 35mA, TX mode 90mA ( includes onboard relay )
  • PC Board Size: 94 x 55mm

Kit Constructors Alert:

1/ There has been a report of failure of one of the NDT2955 MosFETs due to shorting out the RX power to ground. Please let me know if you have had any issues with MosFET failures as the PTC and high current capability of the MosFETs should protect them from damage.

EME166 Tests: The tests below were done using a spectrum analyzer and tracking generator across the 20 to 500MHz frequency range. Minimum through to maximum is the trim pot adjustment range.

EME166 Minimum RX Gain 20 to 500MHz
EME166 Minimum RX Gain 20 to 500MHz
EME166 Maximum RX Gain 20 to 500MHz
EME166 Maximum RX Gain 20 to 500MHz
EME166 Minimum TX Gain 20 to 500MHz
EME166 Minimum TX Gain 20 to 500MHz
EME166 Midrange TX Gain 20 to 500MHz
EME166 Midrange TX Gain 20 to 500MHz
EME166 Minimum TX Gain 20 to 500MHz
EME166 Maximum TX Gain 20 to 500MHz

Changes and Modifications:

1/ The PC board had minor changes to update it in July 2014. The circuit is exactly the same and no changes were made to the component values.

2/ A modification to allow easy switching of Linear Amplifiers that require a grounded input can be found here. The BC847 will easily switch the input of most amplifiers as only low current is required.

3/ There has been a report of the onboard relay not deactivating in RX mode. The fault was traced to the 2N7002 that drives the relay that was found to have leakage from the drain to gate. The 2N7002 was replaced and this fixed the fault.

4/ July 2019 Changed the NDT2955 Fets to either BSS308 or FDN338P.