Hi,
I have an Argonaut 515 and the 4 pole filter seems
less than I want. In particular, when I tune "down" in LSB
and go past the center freq and through where the other sideband
is, I eventually get to a place where there is a lot of high
pitched stuff coming through. It seems to be quite a ways down
from where the center freq should be, it is not just the other
sideband coming through, but the outer skirts of the other sideband
come through. It only happens on strong signals, but my other
radios do not exhibit this behavior, it is not overload as I
understand it.
"splatter
like
sounds" nothing rcv LSB
___________|____________|___________|____ on 75 meters, strong sigs.
"center freq"
I replaced the 4 pole filter with an 8 pole filter (model 220) hoping
that would fix the problem. It did not. I then figured I needed a lot
of shielding and grounding for the filter, so I put the filter on
copper board and used RG 174/U even for short runs in the area.
No help.
The one thing that seems to cure the problem is putting the 4 pole
filter back in the RX line where I was going to stick in a CW
crystal filter. It really seems to reduce, if not eliminate
the problem.
Now, I have no problem putting in 12 poles of filtering for the
SSB line in order to cure the problem, but I wonder if anyone has
any ideas what the source of the problem is? Also, if the problem
is inherent, would it be better to stick the 4 pole filter back
in the standard slot where the problem originates and put the
8 pole filter in the RX line only where it reduces the problem?
I plan to put in some relays and switch in a CW filter here from
the mode switch too.
I haven't set the carrier oscillators in this rig. Could they
be off frequency and cause this behavior? I plan to borrow a good
freq counter and do this soon. Ah, I haven't looked at the other
sideband behavior, I will check USB on strong 20 meter signals
today.
Anyway, thanks for reading. I would love suggestions and possible
answers. I am also happy to further discuss this with anyone
interested, including letting you know my eventual solutions.
Clark
WA3JPG
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