Need recommendation:Digital Scope with External Sweep Input?

I have a need to buy a oscilloscope with external horizontal sweep input. I want to calibrate a radio receiver by feeding it a swept signal from my sweep generator and measure the output voltage as a function of the frequency. I have a hard time finding scopes with external sweep inputs (an input that positions the 'beam' on the x-axis as a function of the input voltage on the Horizontal input).

I have never done this before so perhaps this external input is commonly called something else? Since i'm buying a new scope i would consider a 500 MHz bandwidth. Digital scopes preferred.

Thanks,
/John.

Look for "XY Display" mode. Connect your sweep voltage to channel 1 (X), and your signal to channel 2 (Y). Beware, some digital scopes behave strangely in XY mode compared to analog scopes, so you may have to fiddle with various persistence modes and sampling modes to get a decent display.

Thanks. I have XY mode on my TDS220 so i will give this a try when i receive my sweep generator in a couple of days.