WhitakerAudio AM/FM Stereo Tuner 2012, Сборка и руководство пользователя

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AM/FM Stereo Tuner
24) Install the tubes for the FM tuner (V51 through V59). Connect an antenna to the FM antenna
terminals on the back panel. Install the tube socket shields on V51, V52, V53, and V54.
Note: while not strictly required, use of the shields is recommended. The alignment steps
that follow assume the shields have been installed.
25) Switch the tuner on and set the output switch to FM. Tune through the FM band. One or
more local stations should be heard.
26) Change the output switch to FM Stereo and confirm that stations can be heard.
27) If problems are experienced, disconnect power and recheck the installation of all
components.
Unlike the AM tuner, the FM tuner is much more sensitive to alignment issues. As such, it
may not work at first start-up. The goal at this point is to confirm that the system operates. In
order to optimize performance of the tuner it will be necessary to perform a complete alignment.
That will be discussed later. Possible problems at this point include no output or oscillations.
Guidance on dealing with these issues is given in Section 6.1.
28) If an ac ammeter is available, measure the current pulled by the tuner from the ac line. With
an ac input voltage of 115 V, the current draw should be approximately 800 mA.
29) If desired, measurements can be taken of the typical operating tube socket voltages. This
step can be helpful in analyzing problems, if identified in previous steps. Use extreme
caution when making these measurements as high voltages are present. Typical values are
given in Table 6.3.
Table 6.3 Typical Operating Voltages (+dc unless noted)
Tube Pin No. Typical Reading Notes
V1,
6BA6
1 –3 V Voltage subject wide variation as determined by AVC
2 0 V
3 6.3 V ac Measured with respect to pin #4 (heater)
4 6.3 V ac Measured with respect to pin #3 (heater)
5 250 V
6 120 V
7 0.75 V