[time-nuts] 5061A troubleshooting

[Scott McGrath]

How does one increase the EM voltage?

I do have the manual and I have done the LF test but the ionizer and
mass spec voltages were what I was looking for


On Tue, Sep 30, 2008 at 1:11 PM, corby d dawson <cdelect at juno.com> wrote:
> Scott,
>
> The -.210 v one the multiplier is OK for now. The tube value is for when
> the tube was originally tested. As the electron multiplier in the tube
> ages the required voltage needs to be increased (up to a maximum of
> 2500VDC).
>
> If you have a manual I would suggest that you do the low frequency test.
>
> It takes a frequency at 1/2 the zeeman frequency that you apply to a pin
> on the underside of the unit on the long terminal board.
>
> This allows you to test the tube even if the RF circuitry is at fault.
>
> If the low frequency test fails then before blaming the tube you need to
> get in and measure the ionizer voltage (older units a 1VRMS square wave,
> new units 1VDC) and also measure the mass spectrometer voltage with the
> pot at max CW (about +17 to 18VDC.
>
> If everything checks out but low freq. test still fails increase the EM
> voltage to 2500VDC and repeat the test.
>
> If no low frequency response by now the tube has a high probability if
> beaing dead!
>
> If  the test is good then your problem lies in the RF circuitry
> somewhere.
>
> Corby Dawson
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