In a message dated 31/05/2007 16:04:34 GMT Daylight Time,
rblum@... writes:
I think you are seeing the capacitors he added. He says he added 1 mf
ceramic capacitors, and that the diodes were not noisy, because they
"did not reduce the noise at the lower end of the NDB". He apparently
measured or at least noted the noise; added capacitors and inductors;
noted no significant noise reduction; concluded the capacitors and
inductors really weren't needed for that particular R/S supply.
---------------------------------
Hi Bob
The point Len was making is that you can see the added capacitors on the
back of the board but that there are already capacitors across the diodes,
mounted as normal through hole components on the circuit boards, and that could
have been the reason there was no noise reduction in this example.
Whether or not the existing level of noise was considered acceptable does
not seem very clear, altough I get the impression it might have been, the
observation was only that it didn't change.
If you look at the lower photos in the reference given earlier you'll see
that Len is right.
The existing caps look, to me anyway, to be fairly small ceramic types but
they are definitely in circuit and part of the original construction.
You can see two of the original capacitors clearly, a bit of another less
clearly, and can also see from the rear photo that they are across the diodes,
in addition to the later ones mounted on the rear of the PCB.
regards
Nigel
GM8PZR
