I usually mount trafos with rubbers
Even the slightes "buzz" is "amplified" by the box
With rubbers it should become completely inaudible
If not, its no good
Trafos should definately not be heard at all
But it sounds like you have tried all thats possible
When you say "hum", I hope its not from speakers
And its both trafos, and not just one
My favourite
My wife keeps wondering how those things keep disappearing from the kitchen 😀
I even had it (un)mounted externally, up to 18 inches away. Personally, I think something was wrong with the tranny, despite it's ability to provide a different ac...
A sandwich of two thick silicon washers do it.
Totally silent xformers aren't so common... Nothing you can do sometimes.
Totally silent xformers aren't so common... Nothing you can do sometimes.
Strange. I have regular EIs which make absolutely no mechanical noise. It used to be a problem a few years ago, but they are silent even to the touch. Even the piddly little 180Va transformers I had on the F5, they would run hot, real hot, but they were still quiet as a mouse.
bobo,
minor point: silicone, silicon is the hard material used to make transistors (sand).
...everyone else, vacuum pot your iron if you want to get rid of all mechanically induced buzzes. (or buy them potted)
_-_-bear
minor point: silicone, silicon is the hard material used to make transistors (sand).
...everyone else, vacuum pot your iron if you want to get rid of all mechanically induced buzzes. (or buy them potted)
_-_-bear
I know that NP frowns on the idea, but I've been able to get the amplifier to work into the ham bands -- and I found that it was more stable with some decoupling.
"decoupling"
Are you talking about the same
The suggested looks just like a "small" onboard 1000uf supply cap to me
Will that be fit fore classA? one reason I may have my doubts about such
Without knowing enough about, I would rather try and have the main supply caps closer to amp curcuit
"more stable" ? maybe best not say that 😀
Are you talking about the same
The suggested looks just like a "small" onboard 1000uf supply cap to me
Will that be fit fore classA? one reason I may have my doubts about such
Without knowing enough about, I would rather try and have the main supply caps closer to amp curcuit
"more stable" ? maybe best not say that 😀
Well that is what decoupling is. But it is true that NP has expressed strong opinions against decoupling on the F5.
I would assume that this is highly dependent on the actual implementation, but since decoupling can give you better high frequency performance at best, I think it is very much irrelevant for this amp, unless you as jack use it in the ham bands.
I would assume that this is highly dependent on the actual implementation, but since decoupling can give you better high frequency performance at best, I think it is very much irrelevant for this amp, unless you as jack use it in the ham bands.
Oh, I thought "decoupling" was about small filmcaps
But ok, I see it now, theres a small 20ohm resistor added, in the suggested schematic
I my "common logic" and understanding of english, "DEcoupling is the resistor, more than the exstra cap, I guess
Well, I admit to have suggested similar a while back, to have seperate supply fore jfet
And it was explained to me that jfet and outputs are so very closely coupled, so that any differential imbalance from supply may cause severe problems
But ok, I see it now, theres a small 20ohm resistor added, in the suggested schematic
I my "common logic" and understanding of english, "DEcoupling is the resistor, more than the exstra cap, I guess
Well, I admit to have suggested similar a while back, to have seperate supply fore jfet
And it was explained to me that jfet and outputs are so very closely coupled, so that any differential imbalance from supply may cause severe problems
Thanks,
I had ordered fqpf19nc and fqp12p20 before but they are in a to220 case so I can't use them.
regards John
I had ordered fqpf19nc and fqp12p20 before but they are in a to220 case so I can't use them.
regards John
Rjc of those TO-220 Fairchilds is already over 1C/W, but Rjc + Rcs can get messy with insulators.
Only way to keep temperature of the dies under 100C would be to mount them either straight to the heatsink or use an L-bracket with a large mounting area on the heatsink side.
(for 24Vdc rails and 1.3A bias)
Only way to keep temperature of the dies under 100C would be to mount them either straight to the heatsink or use an L-bracket with a large mounting area on the heatsink side.
(for 24Vdc rails and 1.3A bias)