I know this was an old question from @bffargo, but it's a good one:
1) Some old posts / videos show the -3db drop at around 130 MHz when using original firmware at locked 100MHz bandwidth. Once you unlock it to 200, does it still have the -3db drop there or does it get extended? what is the drop @ 200? I couldn't find a definitive post on a hacked one.
I expanded the bandwidth of my SDS1104X-E to 200MHz and used it to measure the output of an IFR 2025 RF signal generator at 0dBm. I compared it with two other scopes: Tek TDS3K and Owon SDS8202.
At 100MHz the signal was flat and there was still no significant drop off at 130MHz.
At 200MHz:
- Siglent: -1.15dB
- Owon: -0.343dB
- Tek: +0.157dB
Note that I didn't have 50R through terminators for the Siglent or Owon so those were measured using a BNC-T and 50R terminator. The Tek scope had internal 50R termination settings. I've ordered a BNC through terminator and will re-test with it and a 6dB pad and report if the results are significantly different.
As others have found, the 3dB point on my hacked SDS1104X-E was between 230MHz and 235MHz, so the hack definitely works.
I'd be curious if anyone has a real (not hacked) SDS1204X-E and can compare Vpp at 200MHz.