Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
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I feel that the guy that had the original post many moons ago was correct. Get rid of it. The job of any good bench technician is to be able to recognize a dog and move on, not beat a $40 radio to death.
Bob Dostall
Senior Technician
On Sat, Feb 15, 2025 at 9:42?PM don Root via <drootofallevil= [email protected]> wrote: Maynard , I¡¯m gonna mess-up your fine writing! .. Sorry.
If there is stray coupling transferring signals at the top end of each
band, we might expect that it would see lower loss at the higher
frequencies, yes ?and that is what is happening, it seems. I¡¯m on the fence ?And even though
there is signal flow at the high end of each band, it isn't very robust
if I recall the earlier messages correctly. I wonder, ?Emanuele was focused on alignment, and said the bottom end was very bad , and perhaps the top was useable, all as I recall, but can¡¯t be accurate.
And we need to keep in mind that there may be two problems here and not
confuse them. Well Emanuele raised one problem, somebody else started into the other. ??
? Richard is thinking about the circuitry between the
antenna terminals and V1, the RF amp and quite appropriately so. Yes but that only matters is you add an external wire to A2 and remove the link ?? ?I think that Hallicrafters changed the S-40A circuitry to eliminate one
coil in that part of the S-40B and it makes the circuitry in the
schematic look as if it is miswired but I don't think it is. Well Maynard, my speculation is that the 40A was not operating so well, possibly because the transformers had too much Q, but the various antennas swung the ?tunning off course, so they flattened the resonance .. all speculation because they kept mucking with band 1 and 2.? We could start a conspiracy case!
To save that one coil, I think they gave up balanced inputs on Bands 1
and 2, but didn't revise the instructions in the manual to indicate that. Well, they don¡¯t want to admit a problem
The other problem is with the tuned circuits between V1 and V2 and I
think that's where Emanuele's problem is.? It is a mystery to me so far, all I know is from what he said; all of the 4 tanks appear to need less capacitance when aligning, and the lower half of the bands are useless[my word].? Many many things have been checked and checked, yet nothing makes sense. BTW I watch ¡°mayday¡± mostly about planes crashing, and long investigations to try to dig out the cause{s}. they try everything. ??
Thanks, Jim T., for the very nice pictures. Those are helpful and of
really good quality. Yes , very good of Jim ?to do all that work
Some thoughts:
1. I don't see any evidence of C62 or a gimmick in Jim T.'s receiver.
If it is working well without that coupling then my thoughts about this
are probably incorrect;? ?we will see
2. The S-85 and S-40B schematics seem to be identical in the circuitry
between V1 and V2. One of them must be incorrect for these various
circuits to work properly;? except for C62???
3. Someone might own and use an S-85 and, if they don't pay much
attention to the lower ends of Bands 1 and 2, they might have the same
difficulty as does Emanuele without observing it.? hard to believe,? but sometimes we buy stuff that works badly and are so disillusioned that it goes to the attic out of sight and some picker finds it 70 years later, and passes it around and around till it comes out here.
? -- don??? va3drl
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