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Re: Water probe: improvements II

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>


Sorry your email got put in a special folder that I forgot to check.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, January 10, 2005 6:56 AM
Subject: RE: Water probe: improvements II

> Original poster: "Denicolai, Marco" <Marco.Denicolai@xxxxxxxxxxx> > > Hi Bob, all, > > The videoamp (closed loop) gain is 2 and drops to 0 dB at about 56 MHz. > It doesn't rise 20dB/decade going down with frequency.

Yes my email was confusing with no neg sign on my dBs or the word down by.
I was referring to the open loop gain.
I had assumed you had added some extra hf gain to the closed loop gain to
compensate for the probe capacitance.
If you try to add more gain than the open loop gain you don't get it that's
what I was trying to say.

> The last pictures on
> http://www.iki.fi/dncmrc/work/hv_divider.htm
> are shot with the best configuration as described above. The little 10
> us bump is very hard to be removed. Pulse generator AC coupling didn't
> help, forget about my "polarization nosense" :)
> The bump simulated well as a 2.5 dB attenuation near 60 kHz. I simulated
> a symmetrical gain increase of 2.5 dB for my videoamp. Tested it at home
> it really reduced the bump in my little probe. Tested it with the big
> probe: no effect.
> Anybody any idea about what that bump is?

I thought I may have suggested in one of my posts that its either a
resonance or mid band drop in gain.

> Anyway, you can see from the last pictures a fall time of about 50 ns.
> That makes 0.36/50E-9 = 7.2 MHz bandwidth. As I was shooting for 1 MHz,
> I am satisfied.

7.2MHz is not too bad