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The 6SC7 is used as a "floating paraphase" phase splitter. At least in the fixed bias version it is very sensitive to hum in the bias supply. Maybe not in the self bias version as used here. However,

6SC7 tubes are renown for developing heater-cathode leakage and for developing inter-element shorts and leakage as well. Often, if you shake one near your ear, you can hear loose whatever rattling

Try another tube. Maybe heater to cathode leakageSent from my Galaxy

Hi Jacques, Took the grids to ground, no hum so it looks like it is coming from the 6SC7 area. Narrowing it down………. I appreciate all of the discussion going on – thank you everyone. We’ll

Jacques, yes or a mysterious additional capacitance. But it is fishy that both L3 and L6 exhibit the same thing and on both bands. Out the door Friday 5pm before Christmas?? From:

Jacques, we have been to predecessors S-40B and S40A which have similarities, but not even the 40A has cores for Band 1,2 RF tuning while the mixer tuning.. well things got us really off the rails.

Jacques Are you sure you are looking at an S-85? I see no indication of cores in the RF tuning for bands 1,2 . Note Bands go 1,2,3,4 up in frequency, but coil numbers go the other way.. gets us all!

Due to health I have to downsize and am selling this Hallicrafters R-274/FRR and the matching speaker. I am asking $550 for the pair. Radio is now working well after I fixed some simple issues.?

IF the variable capacitor is the original one, I cannot see else than the antenna coils that have too much inductance. That will screw both low and hi end alignment. And it is exactly what happen.

Perfect (almost) so this is not the problem. 73, Jacques, VE2JFE in Montreal De : [email protected] <[email protected]> De la part de Emanuele Girlando via groups.io Envoyé :

Emanuele, a good question, but that would hardly be in play when at the top end and aligning. But if there is anything but clean air between meshing plates, likely the capacitance would be greater

Emanuele, Second tough : are you sure that there is nothing in the coils former for both L3 and L4 ?? I never see a receiver in which you cannot “trim” the value of the antenna coil inductance.

C7 plates spacing.. -- Emanuele (IU1KNR). https://egirland.blogspot.com

And the Band Spread variable cap C5A is in minimum position (plates fully unmeshed) all this time ? 73, Jacques, VE2JFE in Montreal De : [email protected] <[email protected]>

Jacques that’s not fair, you are doing your own arithmetic. And much of what you say must be right, but nobody mentioned what C42 is doing. In my quick re evaluation after peaking at the manual,

Sorry: L3 has no core inside, as per schematic. About C7 I am reconsidering the idea: after all when at the top of the bands it is fully open.. so the dirt can interact only minimally... -- Emanuele

Does the rotor plates are positioned in the exact center of the stator ones, or not ?? Please take a picture ! 73, Jacques, VE2JFE in Montreal De : [email protected]

Emanuele, Fantastic pictures, but I do not believe that the C7A tuning cap can be at fault. Obviously the coil have too much inductance, so it’s core have to be moved OUT of the coil (to the top, or

Sorry, that is not true. Looking carefully I can see a thin deposit on the plates: The outer part of the plate looks cleaner as I passed my finger on it.. -- Emanuele (IU1KNR).

I think it's time to narrow? the investigation down and tackle one problem at a time. As the "v1 / V2 coupling" and the "not C62" problems are really intriguing but seem loosely related to the