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Thanks - will try a couple more. I have tapped on it a few times with no change, but have not tried a different one - yet....

Funny, as I was driving into work I thought the same thing, now I have to wait until tonight to try it.......... Will update later

FWIW, I think the best manual for the SX-28A to be found on-line is the military manual TM11-874, which may be found on BAMA at: <https://bama.edebris.com/manuals/military/an-grr-2>

Ch2 and C-43 form a parallel resonant circuit, a tank, if you will. It is in the plate lead of the pre amplifier half of the 6SC7. When the switch is in the position marked IN on the diagram it is

So the hum in question might just be 60 cycle leakage instead of the originally stated 120 cycle?? I guess that this is possible but what is the explanation for the loss of the hum when SW10 is in

Not the right coils used initially, or was it made on a Friday 13 ? 73, Jacques, VE2JFE in Montreal De : [email protected] <[email protected]> De la part de don Root Envoyé :

Don, OK, understand what you mean by “L3 serve both bands” but that cannot explain why either coil cannot be tuned properly to the low frequency alignment value. 73, Jacques, VE2JFE in Montreal De

Emanuele Re Here is what I get: Band 1: main tune dial at 0.54MHz - the bottom of band 1 (C7A fully meshed - maximum capacity) cid:[email protected] ref only.I shriveled it..don

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.