Скачать с ютуб Pixie QRP - Chinese $7.00 CW Transceiver Kit (40m) 業餘無線電QRP в хорошем качестве

Pixie QRP - Chinese $7.00 CW Transceiver Kit (40m) 業餘無線電QRP

I ordered a Pixie CW kit from China for $7.00 via Amazon.com. They generously sent me two kits instead, so technically these are $3.50 transceivers! The video shows the simple assembly and testing of the transmitter and sample reception of some CW signals. The transmitters produce about one Watt of RF on 7.023 MHz, depending on supply voltage, measured on a handy-dandy MFJ QRP Watt Meter/Dummy Load, an inexpensive accessory from MFJ. The transmitter has no side-tone. The transmitted note is heard on this video in a monitor receiver (Icom) and sounded stable with no clicks or chirps. As you can hear, the receiver may be prone to some broadcast station overload at times, the station heard at the end of the video is "World Harvest Radio", a shortwave religious broadcaster. Here is a description of the circuit: Chinese 1 Watt crystal controlled QRP (and QSK) transceiver using minimal parts. Actually the transmitter produces a respectable, stable signal. The receiver is, let's say, "Hi-Fi". The Pixie is a direct conversion CW transceiver. The Y1 crystal oscillator Q1 transistor is always powered. On Transmit, closing the telegraph key powers the single stage power amplifier Q2 transistor by grounding the emitter and amplifies the crystal oscillator output. It has simple QSK, since closing the key also shorts the audio amp LM386 input to mute audio. The amplified transmitter signal is fed thru the Pi output filter to a 50 ohm antenna and about 800mW is produced with a 12V power supply. Transmitter works fine, and it is rock bound without adjustment. You can see related videos in which Carl, WB0CFF recorded my Pixie, and I recorded John's, K9KEU Pixie, Since the oscillator is always on, there is no chirping common to some other one or two transistor transmitters. On receive, whenever the key is open, the transmitter power amp circuit is used as the receiver detector. Received signals come from the antenna in thru the Pi filter. The emitter current to the PA transistor Q2 is limited by emitter resistor R5 and the power amp base-emitter junction is used as the detector. Input RF signals are mixed with the crystal oscillator signals then amplified by LM386 audio amp IC into a pair of earbuds or headphones. There is NO audio filtering, so the product of ALL received signals in the 40m band are fed into the audio amp and one is treated to full "Hi-Fidelity" reception! As an added "bonus" DC receivers hear both sidebands, so (a human being) will hear at least 20kHz of band simultaneously, 10 or more kHz above AND below the transceiver's frequency! The little trimmer pot W1 provides about 1 kHz of adjustment for the receiver's offset. It is probably a good thing this kit has only 7.023 MHz crystals. If a novice built one, they would be likely be totally confused by plethora of signals on other frequencies - none of which they could ever work using the Pixie. At least, in the Extra portion of the band (below 7.025 MHz in USA), the guy building and using it should theoretically understand that concept and not be disappointed in the results of the stock unit. A later video shows the difference if audio filtering is added. That requires modifying the unit. But in any case, I suppose a cheap little kit like this is a motivational project that might stimulate thinking or even lead to other more practical QRP transceiver kits like an MFJ Cub or Hendricks PFR3. 73 Lynn/NG9D