As I had mentioned earlier, the TinySA is not very suited for measurements like this because it doesn't have sufficient shielding. Shielding makes it expensive and heavy. The third harmonic must be breaking through the signal chain of TinySA.
On 2021-06-20 07:16, Rafael Pinto [PU1OWL] wrote:
> Hi Jerry!
>
> At least I can tell you the Chinese LPF is consistent!!
>
> Mine just got here and, lo and behold, there is a 150pF cap on the 80m
> filter! Just ordered a replacement 1.5nF.
>
> Also, 40m is waaaay low on frequency, with the cut off at 5.2MHz.
>
> The 17m-20m is kindof ok-ish, with its cut-off just below 20MHz. There
> is a notch at the second harmonic (28MHz), so I'm not complaining...
>
> The 15m-10m is also ok-ish; the cut-off frequency is at 29.5MHz, so
> I'll probably have to take one turn of the inductors...
>
> 73 de PU1OWL
>
> Rafael
>
>
> Links:
> ------
> [1] /g/BITX20/message/89212
> [2] /mt/83355576/243852
> [3] /g/BITX20/post
> [4] /g/BITX20/editsub/243852
> [5] /g/BITX20/leave/10189903/243852/952924773/xyzzy
