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From: Carl Ijames on 10 Jun 2010 19:33
Hans,

If you are still out there, there are two used high voltage excite amps on
Ebay in the US. Look at item 290360425190 and item 350159383389, each
listed for $999. These are from the Nicolet-designed FTMS 2000 system
(Nicolet, Extrel, Finnigan, Thermo, whatever). They have two independent
channels with differential output, gain of 100, max output of +/- 100 Vpp,
and frequency response starting at about 5 kHz and flat past about 6 MHz,
with response going up to at least 13-14 MHz at somewhat reduced output.
Not quite the output voltage you wanted but having used a few of these over
many years they are great pieces and at that price having something up and
working almost immediately has a lot of attraction no matter what you may
wind up building :-). The second vendor, craig4076, had an almost
mechanically complete (no data system) FTMS 2000 on Ebay a couple of years
ago, with excite amp, preamp, vacuum chamber with dual cells, and 3 tesla
magnet. It looks like they are parting it out (they have a couple of
chamber pieces and the old vacuum control computer listed now along with the
excite amp). Might be worth asking if they still have the dual preamp if
you need one of those, as well. (JL, if you are reading this close your
eyes :-).)

-----
Regards,
Carl Ijames

"Hans Wolfenstein" <hans(a)somewhere.com> wrote in message
news:hqbsst$ubj$1(a)sunce.iskon.hr...
>
> Hello,
>
> I am electronic technician employed at mass spectrometry laboratory.
>
> Current problematics which I am involved includes building a high
> voltage, high frequency discrete operational amplifier which can
> amplify AC sweeps from 100 kHz to 6 MHz with output voltage swing from
> -150 to +150V. Gain is not needed to be more than X10 (we've already
> build separate preamp). My idea was using the MOSFETs in the output as
> for the differential input I considered the "super match" wide band
> dual FETs. Signal is always sine wave which makes job a lot easier.
>
> Load on the output has practically infinite ohmic resistance; only load
> is capacitance of measuring cell (which works in high vacuum) of
> tipically 30pF (it is a system of metal plates that performs cyclotron
> moving of ions but has negligable interaction with ions, much like
> deflection electrodes in classic oscilloscope tube, so current should
> be very small).
>
> Basic topology of the circuit is standard, includes differential input
> (non-inverting and inverting inputs) stage and complementary output
> powered with symmetrical PSU.
>
> Before I got employed in this lab my colleagues have made an amplifier
> based on APEX opamp but it had significant roll-of at frequencies over
> 1,5Mhz (despite to nice looking computer simulations), not to mention the
> price of these opamps.
>
> Demands are looking "heavy" - there is a large AC voltage swing and wide
> freq. bandwidth. Does anybod have recommendation about construction and
> parts choice ?
>
> Thank you.
>
> Hans


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