Before I forget I'm using opto couplers for plate voltage and current to the VTVM 'cause I use a plus minus supply that needs a floating ground. So plus minus 1500vdc for the plate supply on a floating ground for the plate circuit, and 500vdc plus minus at an earth/input/output ground for the screen and control grid, with the screen at earth/input/output ground so I can run control grid swapped to input ground for drive from the transmitter.

On 9/6/2013 9:00 AM, n8zu wrote:
Before I forget I'm using opto couplers for plate voltage and current to the VTVM 'cause I use a plus minus supply that needs a floating ground. So plus minus 1500vdc for the plate supply on a floating ground for the plate circuit, and 500vdc plus minus at an earth/input/output ground for the screen and control grid, with the screen at earth/input/output ground so I can run control grid swapped to input ground for drive from the transmitter.

I haven't noticed anyone asking you why you want to build a VTVM for
this purpose. Why not use a circuit designed in the last 50 years? Is
there some inherent advantage to a VTVM in this application that a
transistorized circuit would not be able to improve on? Or is this a
nostalgia effort?

--

Rick

Hey OM

I guess every one knows that anything designed in the last 50 yrs is susceptible to electric surges that would be present when something terrible goes wrong, like run away parasitic oscillations, that would wipe out any solid state devices.
73 PM
de n8zu



I haven't noticed anyone asking you why you want to build a VTVM for

this purpose. Why not use a circuit designed in the last 50 years? Is

there some inherent advantage to a VTVM in this application that a

transistorized circuit would not be able to improve on? Or is this a

nostalgia effort?



--



Rick