RF Parts Svetlana 572B Vintage Vacuum Tube Pair Ham Radio Amp Final (Test 82%). These are vintage 572B tubes, made by RF Parts Svetlana. The test results are as follows.. Tube 1: 996 (83%). Tube 2: 978 (82%). The tube(s) in this sale have been carefully screened to ensure your satisfaction. We meticulously inspect each […]