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The state of the art TCXO (Temperature Compensated Crystal Oscillator) UNIT for the Kenwood TS50, TS850, TS870, TS690, TS570D, TS950, TS450 and any other rigs that accepts the Kenwood SO-2 TCXO

I have developed this board as a aftermarked replacement for the Kenwood SO-2 (L77-1394-.5) TCXO unit, which is no longer available as original spare part:


The original Kenwood SO-2 TXCO UNIT, installed in a TS850

The new SO-2NG TCXO UNIT was designed for a improvement of the frequency stability and accuracy of many Kenwood rigs. If you looking for a solution to keep the frequency of your rig stable over a wide temperature range, then is a TCXO the right choise!

As replacment for the Kenwood’s SO-2, the new SO-2NG TCXO board was developed around a high stability TCXO module from Murata providing a high degree of frequency stability over a wide temperature range and a low noise linear voltage regulator, which can achive better results than the original Kenwood SO-2. Optionally is possible to use a SiTime Precision Super-TCXO with an amazing stability of ±0,1ppm.


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SO-2NG Specifications:

  • Output frequency: 20MHz
  • Output level: 1,8 Vpp
  • Frequency stability: ±0,28ppm (or with extra high stability option: ±0,1ppm)
  • Operating Temperature Range: -20 to 70°C
  • power supply requirements: 4,5 to 28 VDC, max. 3mA (or with extra high stability option: 4,5 to 12 VDC, max. 49mA)
  • Frequency adjustment range: 90Hz (±5ppm) (or with extra high stability option: 100Hz)
  • Board size:  20x20mm

The SO-2NG output signal spectrum:

The SO-2NG phase noise measurement results:

The SO-2NG output signal under load condition

The SO2-NG is 100% compatible with the Kenwood SO-2, with the same dimensions and all soldering pads are in the same location as on the original unit, which permit a easy installation. There are also a high quality multiturn trimmer for a fine frequency alignment of the transceiver after the installation of this board.

The new SO-2NG TCXO UNIT mounted in a KENWOOD TS850:

Installation notes only for SO-2NG with extra high stability option:

Due to the higher current consumption of the extra high stability option (±0,1ppm), a modification must be made on the following transceivers:

Kenwood TS850: Short the R93 on the PLL-Unit


Kenwood TS450/TS690: Short the R10 on the PLL-UnitTS450-690_HSmod


Kenwood TS870: Short the R504 on the RF UNIT:PLLTS870_HSmod


The SO2-NG TCXO is available from RF-SYSTEM‘s webshop.

For other questions please send me an email.