[R-390] Tubes new or used?

[Steve Hobensack]

Ballast tubes work. Plug a Mr. Coffee coffee maker in on the same line as 
your r-390. Listen to a popular  ham ssb frequency for a while with a 
resistor in place of the ballast tube. You will hear the audio change pitch 
up and down at about 5 minute intervals as the hotplate cycles on and off. 
Try it again with the ballast tube.
...73 ...Steve..N8YE