[Boatanchors] measuring ripple?

[eugene at hertzmail.com]

Hello all,

I have been working on a heathkit sb-610. Seems my tone output has 60hz
hum on it. So I want to use my scope to look at the ripple on the +215V
plate supply for this circuit.  My scope is a tek 475.  Can I simply put
the coupling on AC and connect to the 215v line? I am afraid that 215 is
too much for the scope. I understand that putting the scope in AC mode
puts a cap in series to block any DC, but surely there must be a limit
to how much DC it can block, no?

Are there other ways to do this? Can I use my DVM in AC mode or
something? 
Thanks