[Test-Equipment] Re: H-P 400 series, addendum

[Fred Olsen]

> Gary Chatters wrote:
> and found a schematic for the 400GL which indicates that the
> lower/black binding post is at chassis/power safety ground and thus
> is not floating.  Then I did the obvious thing and checked a 400F
> with an ohm meter and the black binding post is 0 ohms to the chassis
> and the safety ground pin on the power connector.

And the VERY NEXT thing I would have said was "ohmmeter".  ;<)
That pretty well establishes that all of the 400s are ground referenced,
so take care with any elevated measurements.  The tube versions will
take a pretty nasty ground fault with minimal damage, rather like an old
Tek 530/540-series scope.  Not so the solid state ones.

> It seems to me that a floating input would be very useful for
> metering balanced audio lines.

And thanks much to Russ WA4POD for reminding of the bridging transformer
accessory, the model number of which escapes me.

Fred