bktheking
Gitter Done!
I got in touch with Bill Ammons who is represented on fmtunerinfo.com, he has made some PCB's for the TU9900- one replaces the stock filter on the FM IF board named SFW Narrow IF PCB , PCB's with modern DIP IC's (OPA134's) to replace the old TA-7136 SIP's and a Stereo Separation Control PCB- This PCB adds a second stereo separation control to the 9900. When the tuner is switched in the narrow IF mode, the PCB applies the proper compensation to optimize stereo separation. Typically this PCB increases stereo separation in the narrow mode by 20 dB.
Today I installed 2 of the 3, the Filter PCB and the PCB's to replace the IC's.
The installation, all said and done, was approx an hour. The results?
I've been playing the tuner for a couple of weeks now, stereo and stations tune in well but I heard artifacts behind the music- it wasn't the quietest of tuners, especially in stereo. After the upgrade the artifacts are GONE and stereo comes in crystal clear now. I emailed Bill today with my comments and results, he also replied with the same results:
I have a TU-9900 in for an upgrade. The narrow IF measured just over 3% in the narrow IF mode. With the new PCB and filters in place, the distortion has dropped down to 0.18%.
These numbers are HUGE which also solidifies my findings, distortion with the TU9900 in stock form is audible.
Shot of the stock filter:
Shot of the PCB with new filters installed:
Today I installed 2 of the 3, the Filter PCB and the PCB's to replace the IC's.
The installation, all said and done, was approx an hour. The results?
I've been playing the tuner for a couple of weeks now, stereo and stations tune in well but I heard artifacts behind the music- it wasn't the quietest of tuners, especially in stereo. After the upgrade the artifacts are GONE and stereo comes in crystal clear now. I emailed Bill today with my comments and results, he also replied with the same results:
I have a TU-9900 in for an upgrade. The narrow IF measured just over 3% in the narrow IF mode. With the new PCB and filters in place, the distortion has dropped down to 0.18%.
These numbers are HUGE which also solidifies my findings, distortion with the TU9900 in stock form is audible.
Shot of the stock filter:
Shot of the PCB with new filters installed:
Last edited: