We shouldn't have to do anything with the Calibration for a DG4162. This is only required for the DG4202 (200MHz hack). There are also a couple of other small glitches we can run into with the DG4202 modification. Which is why I now suggest staying away from the DG4202 hack. And you can also loose your hack and end up back with a DG4062 by installing a recent Firmware release update. And then end up SOL for going back to even a DG4162 (the preferred model).
How I would measure the DG4162 output level frequency response: I would set the DG4162 for 50 Ohm output impedance (preferred for these higher frequencies for a flat output into your 50 Ohm Input device). If I used an O'Scope then I would Terminate its input with 50 Ohms (either internally, or with a 50 Ohm Feed Through Termination). The measurement should be into a 50 Ohm measurement device using 50 Ohm Coax. A RF Power Meter, Spectrum Analyzer, etc. is preferred over a O'Scope for better output level measurement accuracy. Although many hobbyist may not have this type of equipment, and therefore an O'Scope may be the their only choice, and should be fine if it has at least a 200MHz BW.
Edit: If a 50 Ohm Feed Through Termination for the O'Scope isn't available, a BNC Tee Adapter (one Male port and two Female ports) with a BNC 50 Ohm Termination on one of the BNC Tee's Female ports can be used. If a 50 Ohm Termination isn't available, a 50 Ohm resistor can be soldered to one of its Female ports (with very short leads). If a BNC Tee Adapter isn't available, I believe that they can generally be found at a Radio Shack store.
Thanks
ted572 for your comments! My DG4062 was modified to DG4202 for a while, but the recent DSP v01.10 firmware wouldn't install on my unit (possibly I was still using the bootloader before v01.06 which was released with the previous DSP v01.09 firmware), and so I ended up downgrading to DSP v01.04, then upgrading to DSP v01.06, applied the DG4162 model, and then upgrading again to DSP v01.08.
Anyways, I appreciate your comments and from your notes my oversight was obvious --- I forgot to set the scope input to 50 Ohm impedance. I repeat the measurements (600mVp-p sine wave, 1MHz to 159Mhz sweep over 10sec) now with 50 Ohm output on the DG4162, and the o'scope (MSO2072A modded to MSO2302A) input set to 50 Ohm internal impedance. I used RG-58 A/U coax.
The results I obtained this time were much better, although the first was still much different than those
published earlier so I repeated the frequency sweep with 3 different coax cables I have (different manufacturers). I'm surprised to find significant differences with simple RG-58 A/U! I have attached the screenshots from the o'scope --- you can easily see the 10sec over which the frequency sweep runs.
The last result seems very good. I have to conclude no problem with the DG4162 calibration, and that lack of 50 ohm termination and coax quality was responsible for erroneous earlier results. It is good to see things working correctly this time.
Anyone feel free to leave some comments or post comparisons of frequency sweep from your DG4000 units.
Edit: Some extra info. My AWG is DG4162 model (updated from DG4062), with following hardware/firmware revisions:
Software Version: 00.01.08.00.02
FPGA Version: 00.01.09.00
Hard Version: 01.01
Keyboard Version: 04.01