Ramsey Electronics FR1 Assembly And Instruction Manual page 13

8. Using your alignment tool, slowly rotate L1's slug gently so that the slug is
even with the top of the coil form. (Do not force the slug; if it binds, rotate the
slug back and gently 'rock it' to-and-fro as you would a thread forming tap.
Slugs are by nature very brittle and will crack easily). Now carefully rotate the
slug into the coil form seven turns. The slug will be in about 1/4 of an inch.
Rotate the tune control until you hear an FM broadcast signal. Adjust L2 for
best sound.
9. Install R9, 10K ohm (brown,black,orange). R9 adds in AFC voltage to
stabilize against drift. Without it your radio may 'wander'.
10. After a signal is received, rotate the tune control to receive other stations. If
the stations seem to 'jump away' as you try to tune one in, the coil L1 is
adjusted incorrectly and should be retuned. The reason for this odd
phenomenon is that the AFC circuit is pushing the signal away rather than
pulling it in. This is caused by having the oscillator 10.7 Mhz below the desired
signal rather than 10.7 Mhz above it. A similar example of this is closing your
eyes, hearing a sound, but not being able to determine if it is in front of, or
behind you. Readjusting L1 will correct this situation. Make sure the slug is
about three turns from the top of the coil form.
11. Calibrating the receiver is easy:
a. Tune in a station known to operate at the low end (88 Mhz) of the
FM broadcast band.
b. Rotate the tune control almost fully counter-clockwise to where
that station should logically be located on the dial.
c. Turn L1's slug until that same station is received. The tune
control should now tune in the entire FM broadcast band.
RECEIVER SENSITIVITY
Your FR1 FM receiver will exhibit sensitivity equal to most standard radio
receivers. For the ultimate in sensitivity when using an external antenna, our
SA7 broadband preamp is an ideal choice. Or, our AA-7 Active Antenna
interfaces extremely well, boasts both an internal telescopic whip, external
antenna jack and even a matching case!
OUT-OF-BAND OPERATION
Although many folks use their FR1 for comfortable FM broadcast reception,
some James Bond types will want to use it to receive clandestine transmissions
from phone bugs, room transmitters and the like. It's a simple matter to retune
coil L1 to receive the frequency band of interest; however, we ask that you first
verify that your FR1 receives the FM broadcast band correctly before retuning.
FR-1 • 13