Ramsey Electronics FM-100, Сборка и инструкция по эксплуатации

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FM-100 Page 51
ADJUSTING YOUR FM-100 TRANSMITTER:
Keep all tests very brief until you have carefully chosen an open operating
frequency in the FM broadcast band.
1. Transmitting Frequency:
After finding a suitable "open" frequency in the 88-108 MHz FM band, adjust
the frequency by first getting the FM-100 into setup mode by pressing both
FREQ keys at the same time. Then use FREQ UP and FREQ DOWN keys
until you hear the carrier frequency on a nearby FM radio. No audio input is
needed to make this first adjustment, you can simply listen for a "quieting" in
the normal background noise "hiss."
The modulation sensitivity of your FM-100 will vary from one end of the
broadcast band to the other. This is explained by the characteristic curve of
the varactor diode. In order to maintain the proper 75KHz deviation, your front
panel level control should be set so that the audio level meters read as
follows:
88.1 MHz to 92.9 MHz. . . . . . . . . +6 on meter
93.1 MHz to 99.9 MHz. . . . . . . . . 0 on meter
100.1 MHz to 107.9 MHz. . . . . . . -3 on meter
2. Audio Connection:
Hooking up an audio source to your FM-100 is really quite simple. However,
there are some general rules:
•
A terribly distorted sound is a sign of too much audio level. Simply
rotate the level potentiometers, R23 and R35, CCW to reduce the
level. Make sure you rotate each one about the same amount to
maintain proper stereo balance.
•
Stereo LP turntables are low-level output and will require the use of a
preamplifier for proper audio input to the FM-100.
•
NEVER connect the FM-100 audio inputs to speaker outputs of a high
power stereo system; such a connection will destroy the IC chips.
3. Stereo balance:
Adjust R15 for correct stereo transmitting balance. If you are not transmitting
in stereo adjust R15 to its center position. The better your ear for music and
your understanding of quality audio devices and interconnections, the better
will be the performance of your FM-100.