第16页
the foxx-3
derek alexander g4gvm, 52 brockington rd. bodenham, hereford. hr1 3lp
never having seen this circuit, or its predecessors, i was intrigued by the foxx -2 9sprat 91) and impressed by the results on 80m - it gave me 1 watt output and a good number of qso's.
for me, the essence of this diminutive is the oscillator and pa/mixer and i see no reason to make life difficult with such low audio, manual changeover and no sidetone.
leaving the basic circuit as it stands, i set about removing the audio, keying transistor and manual changeover switch, and adding the circuits, which replace them, together with the sidetone oscillator. i venture to call it the foxx - 3.
the circuit are self-explanatory, but note the addition of the 82p cap on 80m to increase the offset to about 500hz and the diode to stop the 12v on rx operating the sidetone.
the new audio circuit, which includes a pre-amp, uses very few components and gives a substantial increase in level, driving an 8 ohm speaker easily. a muting circuit has been included to reduce the thumps on changeover and is worth the additional componets. i have used the second input port of the lm386 for the sidetone oscillators need plenty of gain and a bc109 or better is required here.
summary of changes to original circuit:
1. insert 1n4148 between atx and junction c3/r1.
2. insert 82p cap between btx and junction c1/xtal, for 80m only.
3. replace existing audio with fig 2.
4. replace tr3, associated keying components and changeover switch, with fig 3.
5. add phase shift oscillator, fig 4.
6. possibly substitute the 1k pot with a suitable "plug-in" resistor (eg 3k9 for 80m - lower for 40,20 etc).
i have found low profile dil socket pins, which plug in to each other, provide a useful source from which to construct plug-in units such as low pass filters.
this fascinating little fun-circuit is great to use. mine measures 2" x 2.6" x 1.25" high. refer also to sprat 91.
n.b.t.v.a.
the narrow bandwidth tv association (founded 1975) is dedicated to low definition and mechanical forms of atv and introduces radio amateurs to tv at an inexpensive level based on home-brew construction. nbtv should not be confused with sstv which produces still pictures at a much higher definition. as tv base bandwidth is only about 7khz, recording of signals on audiocassette is easily achieved. a quarterly 12-page newsletter is produced and an annual exhibition is held in april/may in the east midlands. if you would like to join, send a crossed cheque/postal order for ￡4(or ￡3 plus a recent sprat wrapper) to dave gentle, g4rvl. i, sunny hill, milford, derbys, de56 0qr, payable to "nbtva".
the foxx-3
derek alexander g4gvm, 52 brockington rd. bodenham, hereford. hr1 3lp
我在以前从来没有看过这个电路，或者它的原型，但是《sprat》91期上的foxx -2激起了我的兴趣，因为它在80米波段的表现给我留下了深刻的印象——它能够提供一瓦的输出，我用它获得了大量的qso's。
对我来说，这个小收发机的本质上为振荡器与pa/mixer，缺点和明显：这样小的声音、手动切换与没有侧音。
我保留了基本的电路，替换了音频、发射晶体管和手动切换开关，外加侧音振荡器。我斗胆称它为foxx - 3。
本电路不需要注释，但是请注意附加的82p电容，在80m波段，它能够增加大约500hz的偏移，二极管是为了进行侧音时，阻止12v加在rx上。
包括前置放大器的新音频电路只使用了非常少的元件，但是获得了实质上的增益，它可非常容易地驱动一个8 ohm的喇叭。一个内置的静音电路被用来在切换时减少thumps，它用得恰倒好处。我使用了lm386的第二个输入口作为侧音振荡器，但它需要充足的增益，这里就需要一个bc109或者更好的晶体管。
原始电路更改的摘要：
1. 在atx与c3/r1的连接点之间插入1n4148。
2. 在btx与c1/xtal的连接点之间插入82p的电容，仅仅用在80米波段。
3. 用图2替换现有的音频电路。
4. 用图3替换tr3与相关的发射元件、转接开关。
5. 增加图4所示的移项振荡器。
6. 可能的话，用一个合适的“plug-in”电阻（例如：在80米波段使用3.9k欧姆——40米波段或者20米波段更小一些……）来替换1k的电位器。
我找到了不引人注意的dil插针，它们可以互相接插，因此在做“plug-in”模块时非常有用，例如：低通滤波器。
这个有趣的小电路使用起来非常顺利。尺寸为2" x 2.6" x 1.25"。参见《sprat》第91期。
（广告不予翻译）
n.b.t.v.a.
the narrow bandwidth tv association (founded 1975) is dedicated to low definition and mechanical forms of atv and introduces radio amateurs to tv at an inexpensive level based on home-brew construction. nbtv should not be confused with sstv which produces still pictures at a much higher definition. as tv base bandwidth is only about 7khz, recording of signals on audiocassette is easily achieved. a quarterly 12-page newsletter is produced and an annual exhibition is held in april/may in the east midlands. if you would like to join, send a crossed cheque/postal order for ￡4(or ￡3 plus a recent sprat wrapper) to dave gentle, g4rvl. i, sunny hill, milford, derbys, de56 0qr, payable to "nbtva".
第17页（由于穷，暂时没有19寸的显示器，只能够截图为4幅，希望哪个有￥人截图个完整的！！）
