RX Up-converter LO Capability

Introduction

Following the opening up of the 71 MHz band for DATV, Mike G0MJW designed an up-converter to enable the MiniTiouner to receive 71 MHz. This was published in CQ-TV 260 (pp 14-15). The up-converter requires a local oscillator in the 350-450 MHz frequency range, and the ADF4351 in the standard Portsdown build has the capability to supply this signal, and a second output socket. This capability (introduced in software update 201807040) enables the ADF4351 to generate the LO signal when it is selected to transmit.

WARNING - when the LO is running and the Portsdown is not set to transmit, there could still be 10 mW of RF at the LO frequency present at the output of the Filter Modulator board.

What Frequency?

Mike recommends a 400 MHz LO in his article. This would require the MiniTiouner to be set to 471 MHz. An alternative would be to use a 366 MHz LO, which would mean that 71 MHz would be transverted to 437 MHz - an existing MiniTioune preset for most users.

How to set it Up?

To enable the LO, simply go to Menu 3 on the touchscreen and select "Set Receive LOs". In the "Receiver LO Setting Menu", select 71_MHz (or any other band that you want to enable the LO for) and then enter the desired frequency in MHz. If you enter 0, the LO will be disabled (the default state).

What is the Output Level?

The ADF4351 is set to level 3, its maximum output level.