Output Pentode - A sweep tube used in Drake Transceivers - usually 3 of them. So long as you hold the average power down, these can last. If you spend too much time tuning, they may not. Hard to get these days hence the price. As they live mostly in the US, our dollar is causing a few pricing issues. These are NOS. Surplus Sales of Nebraska have heaps apparently, so you could try them if you want to pay the postage.. :]

These are also designated 6LQ6.