[MrFixr55]

Hi Roy,

So the plate of the 6F6 is fluctuating now? If there are fluctuations in voltage with the volume control down, then there is an issue.

You may want to heat up all the joints, especially those not made by you. Verify that all caps, electrolytic and paper are replaced. Electrolytics definitely go bad over the years and especially the older pre-war wet electrolytics. For this set, for Caps #62 and 60 should be 450V. Make sure that you replaced caps, especially those in the Bakelite blocks. Don't bridge caps with new ones.

After that, do the tap test. Tap individual components, tubes and junctions (of course, use something non-metallic but with some weight). Whatever you tap that causes a disturbance, investigate there.

Output transformers and field coils can arc. This will definitely wreak havoc. If you have another set with a single 6F6, 6K6, 41, 42 or 2A5 and all the radio's B+ load goes through the field coil, consider subbing the speaker if you can't find the cause of the issue.

Hope this helps.


BTW, set your Isotap to 115V if you can. (The schematic specs the AC power supply to be 115V.) 120V is about 4% or so high, as is some of the DC voltages. For example, 250 V on the 6F6 plate as opposed to 240V is about the same amount of error. Check the AC at the radio's power transformer input lead connections to ensure that it is not fluctuating also. Verify that the power switch is not erratic.