Ramsey Electronics FX-440 Manual page 137

(and hear) the results of all your hard work. If you are still awaiting your
ham license, you can test the FM modulation of buffer stage 010 and
also enjoy your receiver fully. Be aware, however, that the buffer stage,
even with no antenna connected to it, has a transmitting range of about
100 feet, even through walls and obstacles.
TRANSCEIVER PLL ALIGNMENT (May also be done before Step TX35)
Our goal in this test is to verify speech amplifier operation (U4), actual
FM modulation of a low-level RF signal (010), and correct operation of
the PLL Frequency ·synthesizer in Transmit mode. If an antenna is
connected for this test, it will affect receiver operation only. The
"antenna" for the 1 O milliwatt output consists of of the lead lengths and
circuit-board traces associated with C76 and C82.
TEST PROCEDURE:
1. Make sure work area is cleaned up and that the PC board is checked
for wire scraps lodged between connections, etc.
2. Set transceiver frequency to 446.00 MHz Simplex.
3. Obtain or make a non-metallic alignment blade capable of turning
trimmer C81.
4. Connect speaker, microphone, antenna and 12-15 volts DC. (Antenna
will serve RECEIVE function only.)
5. Connect a digital voltmeter (DVM) of known accuracy to TP1 (red
+
lead to the test point, and black lead to ground). Set the meter to
the lowest DC range that will handle up to 7 or 8 volts. A digital
voltmeter is used for this procedure because it has the required
high input impedance.
6. With the transceiver power turned on, press the microphone button
and adjust L7 (by sliding the shorting wire) for a reading of 1.0 to
2.0
voe
at TP1. See page 61
I
step #6 for details on adjusting L7.
7. A precision adjustment of C81 requires either a frequency counter
connected to TP2 or a digitally accurate UHF receiver tuned to
446.00 MHz. With the microphone keyed (button pressed), C81 is
adjusted for exactly 446.00 MHz on your Ramsey frequency
counter or a zero-beat 446. 00 MHz signal on a digitally accurate
monitoring receiver. If you cannot adjust the frequency high
enough, clip out
cao,
15 pt.
An adequate initial adjustment of C81 can be made by listening to
your signal on any UHF FM receiver and carefully adjusting C81
for the clearest-sounding signal. OR: adjust C81 for the best
reception of a transmitted signal of known accuracy. This might
be all that you'll ever need to do, but it is recommended that you
make the precise adjustment when possible.
8. While speaking in the microphone, adjust modulation level (R46) for
FX-440 Assm. 75