I recently bought a TS2000 with “extremely low sensitivity on HF”.
Guess what I discovered?
The gas discharge surge suppressor sustained a hit – likely lightning (what else?!) . The photo (above) shows the ionized carbon flash remnants next to a good discharge tube (D9).
In this circuit, the discharge tube was connected directly in parallel with the antenna connector to ground. It really did its job by ionizing the gas so that the lightning energy was shunted to ground.
I’ve never seen one that actually took a hit AND actually worked. Of course, the magnitude of a lightning strike is immense. A direct hit would have vaporized a chunk of the radio, so it’s likely an indirect hit. Also for this case, the residual energy also melted (opened up) an in-line inductor, L13, (downstream from the suppressor) which essentially disconnected the antenna from the radio front end – resulting in “extremely low sensitivity”!
I believe these discharge tubes are mostly being replaced with MOV suppressors or differently packaged gas cartridges. I had a difficult time finding a replacement this this one since this particular part is obsolete.
Parts removed and replaced. My 2nd TS2000 is working great!
BTW, at home I always physically disconnect my antenna from my radio during thunder and lightning storms. Also unplug radios from the AC socket when the storms are bad.