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Vintage Radio Refurbishing Before Restoration
by: Ronald Baker / WB4HFN
The next step in the process is washing the tubes, checking them for good emission and shorts and pin straightening. Why wash the tubes you ask?? Good question, everyone feels better just after a bath or shower, tubes are no different. A tube will always perform better if its cool. The heat from the tube attracts dirt and grease. After several years of this greasy build-up, this residue acts like a winter coat insulating the tube holding it the heat. A clean tube will dissipate the heat much easier and run cooler which may allow the tubes to last longer.
Okay guys, line up for a group picture, big boys in the back, tall guys in the middle and small fry's up front. Here is a complete set of tubes from the Drake TR-4 transceiver, all nice and squeaky clean, can you see them smiling.
Next step its a single file line for all the tubes to get their pins nice and straight. A tube socket is designed to make a solid contact with a straight pin. When pins are bended out of shape they not only don't make good contact it can damage the socket causing loose pins, signal loss and arcing. Have you ever heard, with the antenna disconnected and lot of popping and rustling noise coming from the speaker. One possible cause is dirty or loose pin connections in the tube socket.
Once the tubes are clean with straightened pins the tubes are checked against a known standard, in this case, a tube checker. Realize the only real way to positively check a tube is an in-circuit test compared with a known good tube, and a tube checker is not a good substitute for that. However, what a tube checker will tell you is whether the tube has good cathode emission or its weak and tired due to age and use. A tube checker is also good for detecting element shorts. So the first stop in the tube checking department is at the old Heathkit tube checker.
Well our transceiver is now all put back together, all the hardware have been reinstalled, tubes back in their sockets and crystals installed. Its starting to look like a new radio again. Physical appearance is only half the battle, what happens when power is applied? Will it come back to life or just start smoking, remember just a few hours ago this radio was very wet.