Richard Clark wrote:
On Wed, 15 Mar 2006 15:38:32 -0800, Roy Lewallen
wrote:
Many analog scopes aren't capable of producing a meaningful Lissajous
figure at HF because of the limited bandwidth of the horizontal channel.

This is certainly true for poor scopes. If we are limited to HF, then
those with bandwidths above 100MHz might squeak by. . .

Either you missed my point, or we differ on what constitutes a "poor"
scope. The Tektronix 465, for example, is a 100 MHz scope. Although it's
very long in the tooth now, it's not a "poor" scope by most measures.
But the specifications for X-Y display are as follows:

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5 mV/div to 5 V/div, accurate ± 4%. Bandwidth is dc to at least 4 MHz.
Phase difference between amplifiers is 3° or less from dc to 50 kHz.

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This wouldn't produce a meaningful Lissajous figure at HF.

Roy Lewallen, W7EL