plate voltage for sunn sceptre

[Shewbot]

I just purchased a bias tester probe from amp-head.com, but I don't know what the standard plate voltage for my 1968 Sceptre with KT-88 tubes should be. The instructions for my bias tester explain how to measure plate voltage using my multimeter probes on pins 3 and 8 of the tube. I understand this in theory, but it still makes me a little nervous all the same.
Alternatively, amp-head.com offers a plate voltage tester probe for just under $30. I'm not opposed to spending this, but if someone out there knows what the plate voltage should be, they could save me the trouble.

[Isaac]

Why not look at the scematic? It's posted on this site.

[JoeArthur]

Why not look at the scematic? It's posted on this site.

Definitely... this is step 1.

I wasn't aware anyone made a special device for checking plate voltage readings.  All that's needed is a VOM that you can get from your friendly neighborhood Radio Shack for around 11 bucks.  A special piece of equipment... even for bias measurements is a total waste of money.

Pin 3 is the plate connection.  But trying to measure between Pin 3 and Pin 8 is one sure way to get dead quick.  While pin 8 should normally be grounded in most amps, it means that you will have both hands inside the amp chassis at the same time.  Much better to securely ground the negative lead, sit on the other hand and have only one hand probing pin 3.