开云体育

Been trying out a couple of different preamps lately with the Softrock.? One seems to work fine, steady gain on all bands, but with the other, images are appearing on each side of center.? Why?

Sounds like you might have power supply noise on that preamp mixing in and generating sidebands. Are these two different models of preamp, or two copies of the same circuit?

No, two totally different preamps.? I get images on the one as well as differing gain per band (not a steady increasing gain with higher HF) and also doubling/ tripling of stations.? The other preamp is relatively quiet, no such images, and steadily increasing gain.? They are both hooked up the same way to the power supply too.

On Wed, Jun 23, 2021, 5:53 PM JonI via groups.io <ji425bt=
[email protected]> wrote:

Been trying out a couple of different preamps lately with the Softrock.
One seems to work fine, steady gain on all bands, but with the other,
images are appearing on each side of center. Why?

Do you still see the images with no preamp?

Mike
W0BTU

No, not at all.

The other preamp is relatively quiet, no such images, and steadily increasing gain.? They are both hooked up the same way to the power supply too.

Which indicates a bad preamp or just too much gain.

On Fri, Jun 25, 2021, 1:13 AM Alan G4ZFQ <alan4alan@...> wrote:

The other preamp is relatively
quiet, no such images, and steadily increasing gain. They are both
hooked up the same way to the power supply too.

Which indicates a bad preamp or just too much gain.

"Too much gain" was my first thought. That will certainly do it.

Put an attenuator inline. I use an old 2k pot.

73 Mike
W0BTU