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As I understand it, the first IF frequency of the uBITX (v6) is 45 MHz. In the original code, there is a variable firstIF, which is assigned a value of 45005000L. This appears to be 5000 Hz off Why?

73,
Mark, N8ME

Hello Mark,

That is because the peak of the filter is in average about 5khz off the theoretical value.

For example in one if my uBitx units it was 7Khz off when i measured it.

73, John

Is there a procedure for measuring the filters? I have a NanoVNA, and I guess it's just a matter of finding the appropriate input and output points.?

This is on the uBITX 6

It looks like TP14 might be a good input ant TP16 a good output, Comments?

While I'm at it, it looks like CW2 and CW1 might be candidates for measuring the 11.059 MHz filter.

73,
Mark, N8ME