> Any comments as to why I saw the drop off in power when the signal was > modulated? If anything, I expected to find a soft rectifier tube. Also, > the drop in Ip and Ep associated with the drop in power was about 20 mA and > 20V respectively; certainly not enough to account for a 40W drop in output > power!
It's been too long since I had my fingers on a DX a'hunnert, Mark... but if it's anything like the Johnson equipment, you probably need to pay special attention to the Oscillator and Buffer stages, which affect grid drive. These stages can be mis-tuned, causing an unwanted situation in the control grids of the 6146 finals, which are common in both rigs. No more than 5mA of Ig is recommended on a pair of 6146's. Johnson even had a 'red-line' in some of their equipment, to indicate that grid drive should be 'no more than this level'. Another cause of final instability, would be neutralization of the push-pull final. A most picky and delicate thing, the higher in frequency you operate. Not so critical on lower frequencies. Perhaps these ideas might help your situation... I don't remember seeing the original message. I remember my dad telling the story of how Lee/K5HZR, back when he was one of the Net Control operators of the 7.290 traffic net, here in the 5th call region. Seems that Lee also had a Heatkit "Benton Harbor kiloWatt" (DX-100) and he wore out three different meter switches, always checking everything possible to check on that rig, to make sure it was operating in top condition. What's that? Did I hear some comments from the back row? The 7.290 traffic net has been in operation since Fone was allowed on 40m (1956, I think). None of the regular Net Control operators, nor the people who checked in were on SlopBucket. The mode may have changed, but the Net is -still- in operation, Mon~Sat from 10am to Noon, Central time, and from 1 to 2pm Mon~Fri, and is still operated as a public service. 73 = Best Regards, -Geoff/W5OMR
