I have a TS-723C/U SPECTRUM ANALYZER test-set rack-mount unit which has a tuneable analog frequency dial covering 20 HZ to 20 KHZ. It also has a level meter with various input and output jacks.Unit is clean inside chassis and complete with all tubes,It takes 110 vac input. $25.00 plus shipping. Al,WA1RWB C/O ispoulin at aol.com