I was able to get a used 40dB power attenuator from a fellow ham. It is a 250W version in a very good condition. The attenuator should be usable up to 6GHz.
I did some basic tests with my miniVNAtiny
and with a Siglent SSA3021X with tracking generator
and their big brother, a R&S FSP7 . Here the three different results:
Siglent SSA3021X | miniVNA-tiny | Rohde & Schwarz FSP-7 | |
420MHz | 38,81dB | 38,47dB | 39,25dB |
1.052MHz | 38,23dB | 38,84dB | 38,96dB |
1.680MHz | 38,28dB | 38,06dB | 39,04dB |