Years ago a FSDO/GADO Inspector pulled that one on me on a instrument flight
check.
Al

"
If you've got a good ADF you can tune in an AM broadcast station and
that makes a dandy DG replacement. Pick a station that's far enough
away that azimuth to the station is approximately constant but close
enough that you get a good strong signal. Not that most planes have
ADFs these days, and the ones that do exist tend to be pretty cruddy.