Tips For Evaluating The Alignment Quality Of Your H.H. Scott FM
(Monophonic) Tuner/Receiver, including:
Scott FM Mono Tuner Types:
300/320, 310-(A/B/C/D), 311-(series), 314/LT-10,
330/331-(series)
Terry E.
Riemer has been an avid H.H. Scott fan and collector since his
undergraduate days in college in the early 60's. He has always been interested
in Scott’s tuners because of their quality of design and construction. His
first tuner was an LT-110, which he built as a kit. His interest in Scott
tuner alignment began shortly after completing this kit. The kit, as
pre-aligned by Scott, never performed quite as well as a completely factory-aligned tuner. Since then,
Terry has developed an alignment technique that will
surpass the performance of any factory-aligned tuner.
"Tuner alignment is a passion, not a
profession." He earned a B.S., M.S., and Ph.D. in Electrical Engineering,
and is currently an Associate Professor of Electrical Engineering at the
University of New Orleans. His teaching and research interests include analog
and digital communications, electronics, audio, and digital signal processing.
General Considerations: Set
to "Monaural" Mode and, if applicable, units with "Local/Distant"
switch set to "Distant" position.
Allow tuner to reach normal operating temperatures.
1. Tuning dial calibration should be within ±0.1 MHz of
correct station frequency. There should be no noticeable drift of the
selected station.
2. Connect a good antenna to the tuner and select a FM
station at least 0.5 MHz from any other in your area. This station should
produce at least a ¾ full-scale deflection on the tuning meter or tuning
eye. While slowly turning the tuning dial across this station, carefully
observe the tuning meter or tuning eye. As you tune the tuner from just
below the station to just above the station, the tuning meter should begin
to deflect upscale from the "0" or "1" (low) position or the
tuning eye should begin to close, depending on your tuner model. As you
approach the center of the FM station channel, the meter or tuning eye
should read its (high) maximum and should remain at the maximum as you move
across the center of the FM channel. There should be no secondary peaks or
dips in this region. The deflection of the meter or tuning eye should be
symmetric on either side of the FM channel center.
3. Repeat Step #2 while listening to the tuner audio output.
From just below the FM channel center, the audio output should contain
both inter-channel noise and station program material, but no significant
distortion. As you approach the center of the FM channel, the noise should
disappear and the program material should sound clean and undistorted. The
program material sound level should not decrease or sound distorted at any
point in the region of the channel center, nor should there be a decrease
in the high frequency content of the program material. Continue to tune
the tuner to just above the FM channel center. The program material should
begin to contain inter-channel noise just as it did when the tuner was set
to just below the FM channel center.
4. Repeat Steps #2 and #3 after selecting a station that
produces about a mid-scale deflection on the tuning meter. Note: If you
cannot find a station that produces about a mid-scale deflection on your
tuning meter, remove the antenna and use a short wire instead.
5. No tubes in the "Front-end" or "IF
amplifier strip" have been replaced since the tuner was last aligned.
6. If any of the conditions described in the previous steps
were not satisfied, the tuner most likely could benefit from an alignment.
!WARN!NG!
Please do not attempt to "align" your tuner.
Any attempt to "adjust" any coils, transformers, or capacitors
without the proper test equipment and the experience to properly use this
equipment will almost certainly result in performance degradation of your
tuner!
