To convert MHz to kHz, multiply by 1,000:
9.62 MHz x 1000 = 9620 kHz
To convert from kHz to MHz, divide by 1,000
2780 kHz / 1000 = 2.780 MHz
To convert MHz to meters, divide 300 by the number of megahertz
300 / 7.1 MHz = 42.25 meters
A Note on Image Reception
Radios work by simple mathematics. For example, most tune to a frequency
by mixing that frequency with another (local oscillator) frequency which
is slightly different. This mixing process primarily gives us the two
original frequencies, their sum, and their difference. Well, the radio's
Intermediate Frequency (I.F.) filter normally passes either the sum or
difference frequency, and this is then processed into the sound we hear.
Because nothing is perfect, certain "harmonics" will also get through if
they are strong enough. For example, if a radio's I.F. is 10.7 MHz, we
might be able to tune to a frequency 21.4 MHz (2 x I.F.) above (or below,
depending on the radio's design) a strong signal and hear it! This is more
evident in a double-conversion radio than a triple-conversion radio,
because the triple-conversion radio's 1st intermediate frequency is quite
high. This causes the image to be so far off frequency that it is easy to
effectively filter it out.
So remember that just because a radio doesn't receive something which
another does is not necessarily an indication of a problem. The one radio
may simply not be "tricked" into picking up an image! This rejection of
undesired signals is one reason that a triple-conversion receiver costs
more than a similar dual-conversion model.
You might be interested in finding more out about radio. One good
location to start looking is your local public library. You might also
wish to contact the A.R.R.L., as they are an excellent source of
informative texts on the subject.
Contact:
Amateur Radio Relay League
225 Main St.,
Newington, CT 06111-1494
USA
PRO60 200CH PORT SCANNER
To order parts call 1-800-843-7422 or visit your local RadioShack store.
Reference # Cat.No. Description NP Part #
------------------------------------------------------------------------
11318532 DIODE 1N4002 RECT 600V.1A 1N4002
Q115 10511228 XSTR 2SC2712 SI NPN LO PW 1TD0011
Q305 10513117 XSTR 2SC4215(0) SI HI FRE 1TD0432
10513117 CASE STYLE SC70 1TD0432
Q116 10514107 XSTR 2SK209GR FET N-CH 1TD0553
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