QRP电路问题，高手请入! [复制链接]

看谐波最少要有宽带收信机或示波器，如果波型有畸型既认为存在谐波，且失真越大谐波分量越大，最好是用频谱仪．

从您的电路电流来看还真有可能达到４Ｗ左右，０．６５＊１２Ｖ＝７.8w,就算效率只有５０％也接近４Ｗ了．所以可以佐证上面的测试方法是可信的．

希望多些人发多一些简单但功率大一点的电路（除了电子管，搞不好我真的会去买管子回来）。

受益良多呀 :)

昨晚发射试验时发现推动级8050发射时发热量很大。甚至有时热到不能工作的地步。看来得再改。用计算机的两个电源分开。一个5v做前级供电（至推动级）。12v单独供给功放管。为了减少谐波份量在推动级与功放级之间加入lc选频回路试试。
以上工作纯粹是试验工作。如果各位觉得有 什么不妥，请指正。再下感激不尽。

用的lc选频是1.5uh电感与340pf电容并联的。用lc谐振频率计算软件算得。中心频率为7.050。没办法。只有1.5uh电感。估计做好功率会小很多。功放管换其它试试!

昨晚diy。忘了把12v电源关掉。用铬电焊接功放管不心短路。哧哧一响。功放管和实验板烧了起来。情景颇为壮观！。 各位ham要小心点啊!

95年北京电子报，更简洁的qrpcw机。

这图虽有了。不过功率没达到要求。最少要3w以上10w以下

lew smith - n7ksb's experimental ½w cw transmitter uses a 74hc240 high speed cmos octal buffer. one section servse as a crystal oscilator; four sections amplify the signal; three sections are not used. ic dissipate about 900mw it needs a heatsink. make sure you use a voltage sorce of 7.8v to 8.0v to power this single chip transmitter. if you wish it can directly drive a power mos fet to get about 10-15w output.

all coils are wound on3/8 diam form air core. use no 14 wire. this can be modified to work on 40m and 80m band, any ideas?

this is a very simple 5 watt cw tx based upon a ttl logic chip. there is just one "tricky" component and this is cx. this component should have an impedance of about 10 - 50 ohms, at the frequency of interest. if you wish to reduce the transmitter power, increase the value of cx. it is 'cx' which causes the square wave from the output transistor to approximate a sine wave. the value of cx is the price of simplicity in this tx

it is far better to use too high a value for cx initially, then reduce it to achieve the correct rf output power. the value of cx will depend upon your choice of tr1. virtually any rf power transistor will work well in this application as long as it will handle 800ma continuously. i have even used the bc108 in this application but the rf power output was restricted to about 150mw. cx was about 5x the value quoted above.

the output tuned circuit uses a coil without a ferrite slug. use the usual "rule-of-thumb" formula for the tuned circuit;

coil wavelength (in meters) = number of turns
capacitor wavelength (in meters) = capacitance (pf)



starting values for cx are as follows
(but there is a lot of leeway): 1.8 mhz = 4.7nf 3.5 mhz = 2.2nf
7.0 mhz = 1.2nf 10 mhz = 820pf
14 mhz = 560pf 18 mhz = 470pf
24 mhz = 390pf 28 mhz = 330pf



this will get you 'roughly' in the right area although it could differ widely with different coil formers. the coil output winding is from 5% to 15% of the total number of turns. adjust the output winding before reducing the value of cx. you need the least number of turns that will give you the power needed.

connect + 5 volts to the sn7400 chip and + 12 v to the pa and you will have over 5w of power out. to key the tx put the key in the +12v lead.

you must use an antenna low pass filter with this rig if you are using a good antenna. if the antenna is tuned (magnetic loop/frame antennas etc) then you need not bother with the lp-filter. do not use a linear amplifier for this transmitter. the finished transmitter will fit into a matchbox with a little care.

i remember 1976 well. it was the 200th anniversary of our country, and there were celebrations everywhere. i also remember it as the year that i was first licensed as a ham, with the call wb0yvk in kansas. one of the other things that i remember about 1976 was a very famous article that appeared in qst. it was doug demaw's "tuna tin 2" qrp transmitter construction article in the may issue.

the authot of the pippin is g.m.king g3my. basically, it is a conventional colpitt type crystal oscillator but with the output taken from a low value collector load resistor and direct coupling is made into the base of the pnp device used as an amplifier. the result is a circuit even more simple than the oxo and with considerable advantages.
the small amount of forward bias developed for the pa stage makes it very much easier to drive but is less than the voltage required to actually bias the stage "on". keying is in the emitter circuit of the oscillator stage and when the key is up and no current is being drawn there is no forward bias at all on the pa stages.

how about qrp? before all what is qrp? qrp is working stations on low power (less than 5w). not only that qrp radios are inexpensive, small, simple and can be home brewed. yet you can work the world. a qrp station should be very efficient as every single mili-watt coming out from the transmitter should go out from the antenna. one can not afford to have lossy lines or poor antennas.
the origin of the first version of what has become the pixie transceiver (called micro-80) was done by rv3gm in sprat, the official gqrp club newsletter, and republished in vol 1, issue 1 of qrpp, the official norcal newsletter. david joseph, wa6boy, on page 47 of qrpp vol 1 number 3 came out with a version called the pixie 2 in a pill bottle for 80m or 40m. it was used as the basis for a building contest in dayton sponsored by the norcal club. since that time a large number of the critters have been constructed and destructed all over the world.

this is a very simple one. all the components (or equivalents) are easily available. please note, building a transmitter without a valid license is prohibited.

micro-80 was a complete cw transceiver with full break-in. with a small modification transmitter produces about 400mw (q2 as bfy-51) cw on 3.5 mhz band. receiver is a direct conversion type, sensitive enough to copy most of the signals. transister q1 (2n2222) can be replaced with even a bc108, for q2 use a bfy51 or any other equivalent for 400mw. micro-80 can be easily modified to transmit am voice. unfortunately 400mw will not be sufficient to operate on am as the effective am signal will be only about 100mw.

the automatic frequency offset selection when transmitting and receiving is an optional circuit. proper frequency separation would be 600 hz to 700 hz for cw.

自已在google上搜索 qrp tx吧!

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[quote=ba6qh/qrp]90年代北京电子报曾经连载过cw发信机的讲座，很详细，看看哪位能找到吧，很不错的，按照那上面的做试验成功率很高[/quote]
97年上海一位马先生的吗？我有那本

两个8050能不能接成达林顿形式啊 达林顿管的放大系数很高啊 是不是可以提高发射功率啊

不好意思 让大家见笑了 能不能用npn和pnp管组成达林顿管啊

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不好意思 让大家见笑了 能不能用npn和pnp管组成达林顿管啊

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只不过达林顿管好像是用在开关方面的。如果要增大功率的话可以两个以个并联使用。我没试过。