Heathkit IM-4180 - Page 7

( ) If you have purchased the optional Antenna
Accessory for the Deviation Meter, connect the
thea RE INPUT jack Water Tf nto ta nf tha
antenna to the AND LL WL the AVLULUL. LL
you do not have the Antenna Accessory, use the
length of red test wire, and push the bare wire
tip into the center of the RF INPUT jack.
( } Place the Deviation Meter close to your FM
receiver. Turn the receiver on.
IMPORTANT: In the follow
wing steps, to accurately
align the local oscillator in the Deviation Meter, you
must know the frequency of the stations heard on
eaoatsar ae wteract 44
your FM receiver; for example, one popular MiQwese
station is at 98.7 MHz. and another is at 106.7 MHz.
To adjust the low end of the band, you must select a
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will fall between 25 and 30. Similarly, to adjust the
high end of the band, you should use a station whose
frequency, when divided by 2, wiii faii between 45
and 50. For example ifa etatinn ean he found whose
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frequency is at 99.9 MHz it will meet both of these
requirements (use 100 MHz for easier calculations). In
your own area, you may have to select two separaie
stations.
Refer to Pictorial 6-1 for the following steps.
NOTE: You will be instructed to adjust coil L202 and
trimmer C211 in the following steps. Use the coil
alignment tool and adjust L202 through the converter
= aeaebad COTO A Atwt t totes ny 79 wanth
shield hole marked ‘ bly fA ust CLL C211 VV ELI
the trimmer alignment tool through the shield hole
marked ‘HI.’
(.) 1. Select a weak FM station on your receiver
whose frequency, when divided | by 3 or by 4,
falls between 25 and 30. Set the
Meter pointer to that number.
siatinn
Deviation
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ed
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direction as you listen. to the receiver
speakers for a cancellation of the sound. Do
not adjust L202 further at this time. NOTE: If
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described, use a weaker station or disconnect
the antenna.
id
ji necessary, return your FM receiver to a
station whose frequency, when divided by 2,
ARO SSAA Y y WV ASE AS Lee eee
falls between 45 and 50. Set your Deviation
Meter to that number.
. Adjust trimmer C211 (HT) in either direction
as you listen for a cancellation of sound from
the speakers. Do not adjust the trimmer
f.24h ro
1rur ter at tnis time.
NOTE: If you cannot adjust capacitor C211 to at least
49.9 MHz at the high "requency end, Tefer to” “High
Frequen Adiustment’’ faolloy
Frequency Adjustment” follow this section.
( ) 5. Repeat Steps 1 through 4 until no further
improvement Cail be made.
( } Push the ON-OFF switch to OFF.
f 1 D mts aes = a f.- tha mt oe
\ J ANGLLUVO Lil WWII UL GLILDi1i1d LivUill LIU IVLELOL.
Proceed to ‘‘Main Circuit Board Calibration.”’
High Frequency Adjustment
Refer to the
4
6-1 (Illustration
Booklet, wing §
wing steps.
( } 1. Temporarily remove the converter shield
cover.
. With the trimmer alignment tool, turn
capacitor C211 to minimum — with the
moveable metal rotor down as shown.
. Adjust coil L202 for the high frequency indi-
cation; that is, a cancellation of the sound
from the speakers or a frequency meter read-
ing of 50 MHz
. Following the directions for a low-frequency
reading, slighily compress the ouier piates of
tuning capacitor C212 until the correct
speaker cancellation or frequency meter indi-
cation is obtained.
. Repeat Steps 1 through 4 until both the high
and low frequencies are aligned to within 0.1
MHz.
( ) 6. Replace and secure the converter shield
cover.