Introduction Amateur radio µBITX transceiver

µBITX transceiver

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Ubitx LCD display
Ubitx LCD display

Most kits KV transceivers in the past was characterized jednopásmovosťou or high price. new Modular μBITX (or uBITX, or. MBITX) attracted great interest, as it is a unique device in range 3 to 30 MHz with an output of 10W CW and SSB. It has a digital method of tuning, 2x VFO, RIDE, CW keyer and more. It comes in the form of planted PCB ready for installation in a cabinet with a minimum of additional effort.

Parameters uBITX by manufacturer:
sensitivity 0,2 uV
selektivita: 2,4 8 kHz with a lattice-crystal filters
Range: 500 kHz 30 MHz
Switchable sideband
output power: 10W do 10 MHz, 7W do 21 MHz 2W 28 MHz
step: IRF510s x 2 I am a PA x 2N3904 4 as a driver- Raduino Jemal board with Si5351A generator controlled via Arduino Nano with 2 x 16 LCD display
current price: 129 USD

Budič a PA uBITX
Budič a PA uBITX

uBITX comes already currently in version 5 and there are also a number of adjustments, features that significantly improve radio station. Among the biggest changes include modification control firmware. Upgrade allows you to connect, for example, the touch screen Nextion, S-meter, CAT, IF-shift, simple spectroscope, extension of keys for faster operation, etc..

Adjustments are made in the design for the purpose of improving parameters. Among the important modifications include the addition AGC. UBITX receiver without this circuit difficult to process strong signals. In the photo you can see ND6T AGC

AGC ND6T pre uBITX
AGC ND6T pre uBITX

Principle AGC circuit is so, the stronger signals undergo active resolving a minimum attenuation 0,6 dB. Stronger signals, however, cause a change in conductivity 2N7002 MOSFET transistors, thus increasing the loss on 34 to 50 dB (28MHz a 3,5MHz). This ensures, such that the signals overwhelm circuit uBITX.

Na ? http://www.zendamateur.com/viewtopic.php?p=215016#p215016 It is described by increasing the gain of the amplifier with Q70, which insertion loss eliminates AGC. Increasing the dynamic range describes W3JDR https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/ Is to shift the operating point of the amplifier law. This adjustment can be seen in the photo.

Increasing the dynamic range uBITX
Increasing the dynamic range uBITX

Offers big changes firmware KD8CEC http://www.hamskey.com/search/label/uBITX in combination with the addition of circuits S-meter or buttons. Me interested in the possibility of CAT communications, which works very well.

version 3 uBITX, you own, It has a great the vice in the form of heavy cracking in the transition RX / TX. Adjusting KB1GMX This problem almost solved https://groups.io/g/BITX20/message/66449

Audio-pop úprava uBITX
Audio-pop úprava uBITX

uBITX characterized in some of the bands worse IMD transmitted signal and the harmonic, insufficiently suppress output filters. Improvement can be achieved by replacing relay for better types and modifications in the amplification chain. If these adjustments implemented, the resulting signal can be cleaner than in many transceivers much higher prices. More about problems with IMD uBITX.

Ubitx RX and TX intermediate frequency amplifiers
uBITX RX and TX intermediate frequency amplifiers

For CW operators can be interesting extension compressor SSM2167 https://groups.io/g/BITX20/topic/16775725 Such modules are-purchase via eBay for a few euros.

uBITX transceiver is excellent for experimenters. It provides a large number of modifications and improvements. Many ideas can also be used in other structures, equipment.

Site map, where you can find important information to uBITX:
http://www.hfsignals.com/index.php/ubitx/
http://www.hamskey.com/search/label/uBITX
http://www.bolkesteijn.nl/blog/index.php?page=ubitx-mods2
https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/
https://ubitx.net/