[Boatanchors] Grid Dip Oscillator (GDO) Info Request

[D C _Mac_ Macdonald]

I am trying to repair a Cushcraft R-7000 vertical which suffered a damaged first (bottom) trap when the antenna folded over at the tubing of that trap in a windstorm.  I found some rather detailed help with a Google search that described how to check traps with a GDO.  I have two Millen GDO units, but I am not sure either is functional.  The grid current varies as I tune the GDO across each frequency band, but that is in "free air" without an L/C circuit near it.  Coupled to an L/C circuit, I find NO dip other than what is seen without being coupled.  Supposedly I should see a dip with the coil close coupled to the in-line tubing of a trap.

I don't know if I have an instrument problem or an operator problem.

Suggestions welcomed!

73 de Mac, K2GKK/5​
(Since 30 Nov '53)​
Oklahoma City, OK​
USAF Retired 61-81​
FAA Retired 94-10​