Chromatography Forum

I have never done this but apparently it should be done annually - is this part of your maintenance schedule?

Can someone explain the physics behind it?

Hello

I don't know who told you that it is annual procedure but for Agilent MSD it is service procedure and it should be performed only if needed. It is not routine maintenance job.

Regards

Tomasz Kubowicz

I 'm just curious what is the meaning of 'dipping the coils'?

Regards
Klaus

I 'm just curious what is the meaning of 'dipping the coils'?

Regards
Klaus

With regards to Agilent MSD, it is the adjustment of the RF on each half of the quadrupole to bring the reflected power down to its lowest dc voltage.

In the procedure you begin at a low m/z of 100, enter the tuning program and select "Set RFPA" and that will give a real time readout of in millivolts of the power on the quad. You then adjust the large adjustment screws on the RF board(Top board on 5971/5972 or Side Board on the newer models). You have to be careful to turn them equal amounts in the same direction of rotation to keep them balanced, and you turn until you find the lowest millivolt reading. You then step up through the m/z range in 100-200 m/z increments until you hit maximum where you get the most sensitive adjustment. Normally you will see something like 20-50mv at 100 and higher with higher mass.

This procedure is normally only done when you install a new RF board to tune the RF generator to the quads. The adjustments are done in very small increments and the setting are normally very close to begin with. I have never had to make more than one turn of the adjustments on any board I have installed.

If you are having to repeat the procedure on any instrument then you are probably going to be replacing either the RF board or the analyzer soon as either the board or the quads are failing.

I thought that "dipping" involved immersing them in some liquid

Peter

I recall it took a slotted screwdriver and I did it on my 7 y/o 5975b and it was petty much a waste of time I barely turned the screws at all and the best I achieved was a 1 unit difference.

Thanks all

It was in an a training manual from an Agilent course that said it should be done annually, but when i spoke o my Agilent tech he said that it was rare that it needed to be done and was usually only on set-up of new instruments

i would like to know more why it is called 'dipping the coils' - I presume it is from the adjusment of the coils of the transformer, but my electronics knowlegde is limited.

Thanks all
i would like to know more why it is called 'dipping the coils' - I presume it is from the adjusment of the coils of the transformer, but my electronics knowlegde is limited.

I’m thinking that you are right. But I’m also not sure about these technical terms in english language. Remembering some knowledge from the amateur radio operator exam, I think the answer was told us by James_Ball

You have to be careful to turn them equal amounts in the same direction of rotation to keep them balanced, and you turn until you find the lowest millivolt reading.

By adjusting the electronics you observe a dropping current/voltage: “The Dip”. (A well-known instrument for amateur radio operators is called ‘Dip-Meter’/’Grid dip oscillator”.)

Just my two cents

Thanks all
i would like to know more why it is called 'dipping the coils' - I presume it is from the adjusment of the coils of the transformer, but my electronics knowlegde is limited.

I’m thinking that you are right. But I’m also not sure about these technical terms in english language. Remembering some knowledge from the amateur radio operator exam, I think the answer was told us by James_Ball

You have to be careful to turn them equal amounts in the same direction of rotation to keep them balanced, and you turn until you find the lowest millivolt reading.

By adjusting the electronics you observe a dropping current/voltage: “The Dip”. (A well-known instrument for amateur radio operators is called ‘Dip-Meter’/’Grid dip oscillator”.)

Just my two cents

I was thinking along these lines also. You are looking for the "dip" or lowest point in the curve. Sounds like the "Dip-Meter" is similar to the SWR meter I have used with CB Radio to measure the standing wave and tune the antenna.