bg3mdo / budget_23cm_band_rf_power_amplifier Goto Github PK

is that a MELF Diode across C5 ? maybe a zener ? doesn't show in the schematic

Very nice project, how is the progress with the dual ldmos version ?

Have you tried using an N-type connector on the output? That's a lot of power at 1.3GHz to be going through an SMA connector (although within the rating for good quality ones). For your double transistor board (that I saw on Twitter you are working on), it will be very near the maximum power handling of the SMA connector.

For your hybrid combiner (on Twitter) you could perhaps fit a diode detector at the ballast load port, so that if there is a power imbalance or phase error you can give an indication or logic "trip" to save blowing it up.

I am going to try building one of these and have ordered some transistors via ali.

73 de G4IXT

It is hard to find 100V 0603 NP0/C0G capacitors in small quantities, for C17, C18, C8, C9. I can get 50V ones, or in 0805 package can get 100V ones. Would the larger size of 0805 be a problem at that part of the circuit?

Could you provide some details of how you fixed the transistors? I am thinking of using low temperature 137C Sn/Bi solder paste and a temperature controlled hotplate to solder them onto a copper plate the size of the two half boards and transistor, bolted to a larger heatsink.

I would also be interested to know the dimensions of heatsink you used. I bought two transistors so will build two amplifiers in the hope that one of them will work. If both work I might build a combiner, but at the moment I can only generate 1W of drive power so I will also need a driver amplifier.