[Coco] RGB to VGA boards, test equipment needed

[Kandur]

Would these pocket oscilloscopes do for checking video signals?
If yes, wich one is better? Are there any others under $100?

http://tinyurl.com/p9jx2ec

http://tinyurl.com/ommymqs

Frida y, September 4, 2015, Barry Nelson among other things wrote,
> At 15khz a .1 uf capacitor has an effective impedance of 106 ohms but at the
> color burst clock frequency of 3.58 mhz, the same capacitor has an impedance
> of 0.444 ohms. Since the CoCo 3's composite video output circuit has a 10 ohm
> resistor on the collector of the output transistor and a 120 ohm resistor on
> the base, putting a .1 uf capacitor from the video output to ground should
> effectively ground out the high frequency color burst signal and part of the
> black and white video, but should leave the horizontal and vertical sync
> pulses virtually untouched. This should eliminate the jitter on the 80 column
> screen. If the capacitor doesn't do it by itself you could a small 10 ohm in
> series. This has the advantage of providing sync as well as a proper black level reference signal.

Thanks,
Kandur