This solid state Kenwood KT-9900 AM-FM stereo tuner is the hard-to-find version of the KT-8300 that was sold in Europe. As a result it is friendly to 220v or 110v power. This tuner has been thoroughly rebuilt by Bill Ammons, a contributor to the FMtunerinfo website where there is much more info on this and many other great tuners.Bill Ammon's "full upgrade" for this KT-9900 included the following:
- Replacing all electrolytic capacitors (increasing some values in places)
- Replacing two op-amps in the stereo/audio paths with high speed bi-fet parts
- Replacing narrow IF filters with much lower distortion parts and adding some additional IF gain to compensate for the higher loss of the new filters
- Replacing the two stereo separation control pots with a PCB that has four relay switches to allow independent control of the stereo separation in both the narrow and wide IF bands.
The unit was burned in and aligned on a digitally synthesized test set.You can see evidence of all this work in the photos of the inside. These upgrades are also evident in the improvement of the test numbers before and after the servicing: Prior to the upgrades the test numbers were as follows: - Distortion at 1kHz
Wide IF mode 0.11%
Narrow IF mode 0.82%
- Stereo separation at 1kHz
Wide IF mode 39dB
Narrow IF mode 27dB
- 65dB RF input quieting (unweighted)
Mono -72dB
Stereo -70dB
- 50dB quieting points (unweighted)
Mono 1uv
Stereo 50uv
After the work was done the test numbers are now as follows: - Distortion at 1kHz - 100% modulation
Left Wide IF mode 0.045% Narrow 0.12%
Right Wide IF mode 0.051% Narrow 0.12%
- Stereo separation at 1kHz - 100% modulation
Left into Right Wide IF mode 62dB Narrow IF mode 55dB
Right into Left Wide IF mode 62dB Narrow IF mode 57dB
- 65dB RF input quieting (unweighted)
Mono -74dB
Stereo -71dB
- 50dB quieting points (unweighted)
Mono 0.8uv
Stereo 28uv
It passed all of Bill Ammon's on air tests and he commented that it has a very steep limiting curve on both IF modes (60db with a 110uV input using the narrow IF mode). As you can see the improvements in the test figures is dramatically better than stock. This is a very high performance tuner. So, you might wonder why I'm selling it. The only reason is because I live in an urban high rf area and simply do not need such a high performance tuner to get the stations that I want. If I lived remotely I would certainly not be selling it. For more information, the owner's manual is available here: Kenwood KT-9900 AM-FM stereo tuner owner's manual.
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