[Drake] TR-4 socket problem

[Richard Peterson]

I directly e-mailed Garey (K4OAH), my TR7 and TR4 go-to guy, and he suggested I post this on the site. Fair enough. I had an intermittent transmit audio problem on my TR4, and found a loose 12AX7, the first audio stage in the transmitter section. A simple replacement with a different tube solved it. I did, however, use DeoxIT on the pins, but the tighter-fitting tube really solved the problem...another solution might have been to spend some quality time under the chassis to carefully snug up the individual receptacles on the socket, but it wasn't necessary. My next step -- probably not needed for most persons -- was to next try a 12AT7 to give a little lower gain. My crystal mic is awfully hot, and the setting had been a bit critrical to keep the "S" meter needle from swinging too much when it is looking at ALC in transmit mode. The 12AT7 made it easier to adjust. I'm keeping it in the rig. 
 
Richard
WB5NEN