Another RCA CT-100 discovery B8001599

[Penthode]

Last night I powered up the chassis. The power supplies came up and with the new ballast resistors installed, the voltages appear correct.

The only immediate issue was no audio. I had expected the rush of noise from the speaker and traced it to a short from the plate of the 1st audio IF to ground. Unsoldered and removed the plate connection and the short went away. Reconnected and I heard the rush of noise on power up and then it disappeared. Reasoned that the RF and IF were being biased off so a slight rotation of the AGC control brought up the rush.

Connected the Zenith set top box with its modulator on Channel 3 and I can hear program audio. Looks like all my video audio IF rewiring was okay.

Have made preliminary measurements through the chassis and all seems well. The high voltage is at 22kV and the regulator is working as I can swing it up and down with adjustment. Horizontal sweep is on frequency. The photo below the chassis is running and you will see the Heathkit VTVM reading 22kV with my Heathkit probe. (I bought the Heathkit IM18 VTVM as,a kit in 1971: hard to believe I have been using it for 51 years!)

My ballast arrangement is fine. With the heat sink, the temperature levels at 55 degrees Celsius which is much lower than I had anticipated. And that is with the correct voltage drops to the two B plus branches.

I still am missing a 1mH and 1.9mH peaking coil. The 44AWG wire arrived and so I think I will have a go at that tonight.

The chassis has run about half and hour with no issues.