[Amps] grid resonance

[Tom W8JI]

I've got a problem with a measurement.

I wanted to compare a GDO reading with a network analyzer 
S12 reading, but I'm having some difficulties getting a 
reading on my old Heath meter.

I can't get any kind of dip at all with my dip meter on any 
frequency holding it near the grid lead unless I wrap a turn 
or two around or very near the GDO coil.

I managed to see a dip at about 105 MHz when I wound a small 
one turn coil and installed it between the grid pin of a 
3-500 and chassis, but that changes the readings in an S12 
measurement.

The S12 measurements look perfectly fine of course. Very 
clear patterns.  I'd like to see how a GDO does in 
comparison, but my GDO won't dip on the grid even though it 
will dip five inches from a high Q resonant system.

Anyone ever try this method on a 3-500Z or 811A??

73 Tom