The values on the schematic should be at the moment considered placeholder values.

I still need to go through the schematic and insert the correct values for both AX5043s.

Rich you are correct, the matching network is unique and tuned for each band.

The plan is to work on the VHF network using one of the Raspberry Pi boards I’m building then transfer those to the schematic.

As VHF is uplink it will require fine tuning for optimum performance.

The MRAMs show pullups on the chip selects which may not be needed as well as load resistors on the MISO leads that Kicad balks about when paralleling outputs.

Need to do more research but zero ohm resistors are less expensive than new boards and a lot less time consuming than trace surgery.

In a flight version the matching network on the UHF is not required unless a need arises for 70cm receiver optimum.

I actually laid out the VHF schematic then duplicated it for the UHF and never deleted the inductor which for UHF is a zero ohm resistor

Jim McCullers

WA4CWI

BTW - the external 90nH inductor isn't needed for the UHF chip.  No harm in leaving it in, though.

On Wed, Jan 18, 2023 at 4:07 PM Jim McCullers via pacsat-dev <pacsat-dev@amsat.org> wrote:

Attached are the schematic and layout for the TMS-570 LaunchPad booster board.

It contains two AX5043 circuits configurable for VHF or UHF and places for four MRAMs.

Not all positions are required to be present so the build can be by need.

It does contain the resistors I discussed that may not be required in future versions.

Please give it a review as I’m preparing to send the design to the PCB board maker for a first trial run.

73

Jim McCullers

WA4CWI

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