[Milsurplus] Dippy Meters

[Hue Miller]

> I purchased a James Millen GDO to help, resolve possible problems, check
> the coils Q at rated frequency.
>
> The GDO 90651 it self has problems ... cant win.
> Symptoms : as you roll the thumb wheel forward to increase frequency the
> needle increases from 0 towards 1 ma
> the reverse is true, the needle falls as the thumb wheel decreases
> frequency.  Symptom is the same on all bands, plug in coils.

> Thanks
> Hutch

I have not used this Millen GDO. But - all simple variable frequency LC 
oscillators vary
in output over their frequency range as the capactitor is varied. As you 
tune near the
frequency of interest, say, 3 MHz, for example, you are not able to use the 
level control
to raise the meter needle back to the upper part of the scale?  You always 
need to have
the needle in the upper part of the scale and the level control (or "meter 
adjust" or
whatever your machine calls it ) should be able to do that.  Then you will 
be able to
best see the dip as energy is drawn by a nearby LC circuit tuned to the same 
frequency
as the GDO. These are simple devices and if as you say the few components 
really are
good; the coils all do the same thing, and you cannot use the meter adjust 
control to keep
the needle in the upper range, you had better try a new tube in it.  -Hue 
Miller