ALIGNMENT PROCEDURE:
The following equipment is recommended for alignment of these models:
1. Standard signal generator.
2. FM signal generator capable of sweeping at least 200 kc. at 8.25 mc.
3. Oscilloscope.
4. Voltmeter of 20,000 ohm / volt or better.

RV - in IF ALIGNMENT:

Visual Method:

To align the IF section of the tuner using the visual method, connect the sweep voltage output of the frequency-modulated signal. generator to the horizontal deflection input of the oscilloscope, and adjust the controls until the horizontal sweep nearly fills the screen. Adjust the FM signal generator to sweep from about 8.0 to 8.4 mc., and apply the output to the grid of the second IF stage. Connect the vertical deflection input of the oscilloscope across C24 in the grid circuit of the first limiter. The rectifying action of the grid circuit of this stage will provide a signal corresponding to the amplitude response of the preceding circuits, Adjusting the controls of the scope should produce a picture of the response curve. Always use as small a signal from the generator as possible consistent with a good image. In order to provide a frequency marker for alignment, apply a signal of exactly 8.25 mc. from the AM signal generator to the same grid where the FM signal is applied. This is best done by using a small mica isolation condenser in series with the 8.25 mc. source. Adjust the amplitude the 8.25 mc. AM signal until a small marker pip appears on the response pattern, as shown in Fig. 7. Use only enough marker voltage in all cases so that the pip is just discernible. The location of this marker pip on the curve indicates the center alignment frequency of the amplifier. The adjustment screws of 13 should now be set l'or the desired characteristic. the marker pip should be left at the center or axis of symmetry of the curve. Adjustment of the screws will produce varied patterns.
For guidance, the curves of typical misalignment and proper alignment are shown in Fig. 7. Greater amplitude of the pattern indicates higher gain, so adjustments should be made not only or best symmetry but for optimum gain as well. Having adjusted 13 in this fashion, the output from the signal generators must now be applied to the grid of the first IF amplifier. Next, 12 should be adjusted in the same manner. Signal generator outputs should be reduced as a stage of gain has been added. When 12 is aligned satisfactorily, apply the signal

Generators to the grid of the mixer tube. Align T2 for the best possible response The pattern appearing on the screen at this point is the overall response of the whole IF amplifier and should be similar to that shown in Fig. 7 for proper alignment before going on to align the discriminator.

Meter Method:
Satisfactory alignment can be made using only an AM signal generator and a high impedance DC voltmeter by the following method, although it is considerably more time-consuming than the visual procedure. The meter should have an impedance of at least 20,000 ohms per volt, and be capable of reading negative DC voltage of approximately 3 volts. Connect this meter across C24 in the grid circuit of the first limiter, with the ground side of the meter going to the grounded side of the condenser. The tuning eye employed in the tuner can be used for indicating maximum response. However, this is not as satisfactory as a meter. Apply the output of the AM signal generator to the control grid of the second IF amplifier tube. Set the signal generator to 8.25 mc. When making these adjustments, always use an input signal level which results in meter readings of from 1 to 2 Adjust the screws on T3 for maximum meter reading. The frequency of the signal generator should be changed in steps of 20 or 30.kc. above and below 8.25 mc., and the readings noted in order to determine if the curve is symmetrical about the 8.25 mc. center frequency. If the results show that the curve is not symmetrical, further adjustments must be made and rechecked until a well-balanced curve results. When checks show the desired result, apply the signal to the grid of the first IF Tune transformer T2 in the manner prescribed for 13. When this has been accomplished, transfer the Am signal generator to the grid of the mixer.

FM DISCRIMINATOR ALIGNMENT:
Visual Method:
Alignment of the discriminator is easy with the visual method. Apply the output of the frequency-modulated generator to the grid of the first limiter. Apply a signal from the AM generator at 8.25 mc. to the same point. Connect the vertical input of the oscilloscope across C29 in the output of the discriminator. Make certain that the ground of the oscilloscope goes to the ground side of this condenser. Adjust the controls for the best image, using as small RF signals from both generators as practical. Alignment must be made for symmetry about the 8.25 mo. marker pip, and linearity above and below this point as shown in Fig. 8.

Meter Method:

When only a meter and AM signal generator are available, connect the output of the generator to the grid of the first limiter, and a vacuum tube voltmeter, reading plus or minus DC voltage of about 2.0 volts, across C29 in the discriminator output. Set the frequency of the signal generator to exactly 8.25 mc. Adjust the secondary of the discriminator until the meter reads zero. Change the frequency of the generator in 20 kc. steps above and below 8.25 kc., and note the voltage generated at each step. Readings should increase linearly each side of center frequency out to 75 kc. Should more voltage be generated on one side than the other, adjust the primary of this transformer and recheck. of trials and checks should result in a curve very similar to that shown in Fig. 8.

FM RF ALIGNMENT:
To align the RF portion of the tuner, a signal generator covering 88 to 108 mc. and a DC meter having an impedance of at least 20,000 ohms per volt and capable of reading 3.0 volts are required. Apply the signal generator to the antenna terminals and connect the meter across 024 in the first limiter. signal generator at 108 mc. and set the tuner dial to the same frequency. Adjust the HF Osc. Trimmer (on top of chassis at rear of variable condenser) until the signal is heard or the meter indicates maximum voltage. Set the tuner dial at 90 mc., and the signal generator to correspond. With a non-conducting rod, compress or t and the oscillator inductance as needed to tune in the signal. Return the generator and dial to the high-frequency end and recheck. Readjust the trimmer if necessary. Adjustments of the inductance and trimmer are interacting, and several adjustments of each may be required for exact alignment. Reset the signal generator and tuner dial to 108 mc. Rock the tuning for maximum voltage indication on the meter. the signal level as necessary to maintain the voltage at less than 2.0 volts. the " KF Trimmer " (trimer on the center section of variable) for highest meter reading. Set the generator and dial to 90 mc. and rock the tuning for highest meter reading. Adjust the RF coil inductance with the non-conducting rod for best gain. Here again, several adjustments at both ends of the band will be necessary for the best alignment since adjustment at the one end will affect tuning at the other. The antenna circuit can simply be trimmed at the high frequency'end of the band and left, since the application of antenna or signal generator to the antenna terminals severely damps this circuit and the tuning is not critical. When this adjustment has been made, the tuner is completely aligned.,

DIAL STRINGING CHART:
NOIE: Remove dial plate to make pulleys and drum accessible.

The tuner is designed for best performance with a 300 ohm FM antenna, Many such antennae are commercially available and should produce good results. Signal strength increases as the height of the antenna is increased, therefore, the antenna should be erected in the highest possible location. Losses in lead-in up to 75 ft. in length are unimportant. For those who wish to build their own antenna, dimensions are given on the drawing. The folded dipole shown gives good results over the entire band. It possesses a directional pickup pattern and should be oriented broadside toward the station of most interest or most difficult to receive.

Shielded leads from tuner to amplifier and from phono pickup to tuner are essential.. Two male connectors will be found plugged into the female connectors in the RV - in and eight feet of shielded wire is packed with each unit. Since individual requirements vary, this irc is sup plied uncut and not attached to the male connectors,

When making up the cables, the center conductor should be stripped of insulation and tinned, inserted in the center sleeve of the male connector, and heated until the solder flows making a good joint. Bring the braid up on the outside shell of the plug and solder all the way around.

In most cases, the shield braid will provide sufficient ground between tuner and amplifier. In in frequent cases, some hum may be encountered which can be cured by connecting the amplifier chassis to the tuner chassis with a piece of heavy copper braid. The hum level out of the tuner is very low and the hum experienced will generally be found in the amplifier used or in the method of connection to the tuner.