In fact, I made not many, a just two boards I write this, just want to tell the novice door to note, the master can ignore this post
Components using:
Transistor:
Small circuit, I think 2SC9018 best cheap good effect.
Have done under the same conditions, 2SC9018 often than we say 3DA12A/B/C many, the start-up 2SC9018 other than the transistor easy shock can be said, 2SC9018 excellent value for money
A 2SC9018 down, can also continue to use 2SC9018 continue to enlarge, but also to increase the gain can change 2SC1906 can say after 2SC9018 start-up completely failed to promote the ability of 2SC2053 get a wiring diagram in front of only a amplification 2SC1971, this is impossible, we can gain value based on transistor count (count only theoretical value and actual value is even smaller) will gain multiplied on start-up when the power is converted into multiples of get the theoretical value. magnified several stages is always good.
Capacitance:
I do not think that, under the conditions of the cheapest ceramic capacitors on the election. Mica capacitor is best, but now almost gone. Monolithic capacitors and some other capacitor is generally better than ceramic capacitors in the audio effect.
Resistance:
Have this misunderstanding: metal film resistor noise.
Until one day, I use a knife to cut the resistance outside the paint found spiral metal grinding metal film resistor, it becomes a high-frequency circuit inductance.
Since then understand: why imports emission board with the original carbon film resistor, you can look at it this way: carbon film increases the resistance of the high-frequency signal noise, but this affects only affect the waveform does not affect to his frequency, since the FM modulated only on the frequency, can be said that the carbon film resistor in the FM circuit is almost no effect on the sound quality.
But one thing to note: due to the skin effect and the impact of high-frequency loss, slightly larger than the nominal value of resistor in the high frequency region work.
Inductance:
Say nothing of this, is enameled wire around better silver plated wire, capable of shielding professional with high-frequency transformer, this time should be noted that the frequency of the magnetic core of the transformer is right for you to want to emitted frequency.
It is worth noting that, near the inductor coil in the high frequency (particularly since the wound laps of the kind) is preferably not arranged in parallel.
Bonded Copper:
Personally think the best porcelain plate, of course, this is impossible, the thing with a professional machine, can punch
Fiberboard good market, the best use double-sided, cloth board cloth into a single-sided (left side of the whole ground), so you can eliminate some of the self-excited, but the board have a certain thickness to prevent the lead capacitance between the circuit too effects.
Power:
1W have enough (we all do not want to suffer grasping 1W Logically enough for amateur) and then high (money to the guts to be energy challenge is `` `)
1W tube use 2SC2538, 2N4427, 2SC1970 power is also relatively easy to find
Hand triode, a detailed analysis of the value of its available, such as:
C2839 30V 320MHz
C1959 0.5W 300MHz
C2500 0.9W 150MHz
C1162 10W 180MHz
C1162 is a relatively common tube, 10W, 180MHz stands to reason that it should be used to launch the fishes, because of its relatively high power and pole frequency than C1971 but not critical look at the transmitting circuit power, nor limit frequency, but the gain. example, we often say, C2053, 0.2W, limit frequency is only 175MHz, but its effect than 0.6W, and 1080MHz of 9018 is better.
The gain of the so-called, is a multiple of the signal amplification, a lot of people say: magnification than β value?
I explain here: β value refers multiples DC amplification gain signal amplification multiples, the two are not the same, after extremely high frequency amplification the tube plays enlarge and shock energy compensation, rather than working CPI state (now about IC amplifier is gain rather than the value of β gain unit is db, given me on the table some of the value of the gain of the RF tube)
Look around the C2053 gain:
Model Power the gain voltage frequency working condition package 123 feet
2SC2053 0.2W 15.7dB 12V 175MHz FM / AM TO-92L BCE
9018 gain refusing estimates will not exceed 10db (C9018 original data, and so can only be estimated, but the effect is certainly not 10db)
10dB gain of 10db for standard converts the signal magnification of about 10 times, and C2053 of 15.7dB, enlarged about 20 times (3db = 2 times, 6db = 2 * 2 = 4 times, 9db = 8 times, estimating can count down). compared with 9018 times zoom and C2053 2X times, far worse
The old-fashioned high-power cordless phones (5-10W): shock-the C1906 (0.1W 18db)-C2053 (0.2W 15.7db)-C1971 (5W, 10db)
And some pipe cooling good case can super-power work, I heard someone burn C2053 burn 0.6W (say 1W there, but still not very confident)
C1162 do not launch with is not a high-gain, no value, but also to see there are several in the high-power cordless phones, is mainly used for the switch emitter power without doing transmitter uses, As for the first three tube, do small signal amplification tube.
The now part decibels - power ratio are as follows:
DB power ratio
0.0 1.00
0.2 1.05
0.4 1.10
0.6 1.15
0.8 1.20
1.0 1.26
1.5 1.41
2.0 1.58
2.5 1.78
3.0 2.00
3.5 2.24
4.0 2.51
4.5 2.82
5 3.16
6 3.98
7 5.01
8 6.31
9 7.94
10 10
12 15.8
14 25.1
16 39.8
18 63.1
20100
25316
301,000
Formula:
P (out)
G (db) = 10lg ----
P (into)
