None. The best way to find out if a 6JB6 is good or not is by direct substitution. Sweep tubes were never meant for RF PA use. Tube testers, except for the Hickok brand usually test for tube parameters at 120 Hz or in your case, maybe 100 Hz, not Mhz. Hickok, I believe used 5 kHz for tube testing but this is still far short of what the tube will see in actual transmitter service. Furthermore they do not test them at the power levels you would encounter in a transmitter. However if they have a test function for measuring transconductance they can be used to match various tubes. It's also usefull for testing heater continuity but you can tell that just by looking at the tube when power is applied. You should have a set of spare finals handy in the event that you need to replace the finals. You will know when your finals need replacing when power output on the lower bands is where you would usually expect it to be but falls drastically on the higher bands such as 15 and certain! ly 10 m eters. You don't need a tube tester for that. In general, tube testers can never be relied upon with absolute certainty as the final arbiter of tube performance. Many times it has been found that tubes that fail in the tube tester work just fine in the actual circuit. Personally, I have a love/hate relationship with those things if such a relationship can in fact exist. They are very usefull when going through a batch of tubes and weeding out the obvious problems: shorts, open filaments, leaks. My aversion to them harks back to the days when I started in the business. A technician who reached for a tube tester before making observations and taking measurements was the sure mark of a poor technician. -------------- Original message -------------- From: Bent Jørgensen <[EMAIL PROTECTED]>
Hallo All I need to know which tubetester is the best to use for the 6JB6(A). What can be recommended? Thanks for your help! 73 OZ5ZD Bent Jørgensen
