SBITX - SDR TCVR for designers

Ashar Farhan won the first concession in 1982. On this more than 40-year journey of the radio amateur world, there are milestones such as Bitx, UBITX and SBITX. Although any of these TCVR-ov nemáte na stole, je možné, že ste o nich aspoň počuli.

Bitx TCVR

Bitx is a KV TCVR-A kit, characterized by a simple concept using Bi-Direct amplifiers. This allows you to create a simple but functional SSB TCVR na jedno alebo niekoľko susedných pásiem. Na jednom plošnom spoji je kompletný TCVR, ktorého cena je cca. 50 dolárov. Od prvej verzie z roku 2003 vzniklo viacero verzií a každá si našla okruh priaznivcov.

UBITX TCVR

UBITX je stavebnica CW/SSB TCVR-a na väčšinu KV pásiem (3 to 30 MHz, but works experimentally after 432 MHz). The term kit is no longer quite accurate because the radio amateur just needs to connect the installed flat connections and implement the mechanical construction.

Again, several versions were created and a number of modifications thanks to the openness of the code. Cena uBITX sa pohybovala od 109 dolárov.

SBITX TCVR

Pokrok nezastavíš, a VU2ESE prichádza s novým TCVR-om, hybridným SDR s výkonom 40W (na 80m a 40m) a zabudovanou podporou pre digitálne módy ako PSK31, RTTY či FT8. Again in a favorable price of $ 299 (without Raspberry Pi, display and microphone). The principle that everyone can modify the code.

The aim of SBITX is TCVR, which does not have to be expensive and has excellent features. sBITX je založený na obyčajných tranzistoroch 2N2222 a Raspberry Pi. Pozorný čitateľ už zaregistroval, že ide o hybridný SDR TCVR. To je inak koncepcia, ktorú má Yaesu FTDX-10.

This is a combination of a classic analog filter as a Superhet and SDR receiver. In order to maintain a favorable price and excellent parameters, Ashar had to reach the filter at 40 MHz. The tax for that is šírka SDR 25 kHz, teda zobrazenie spektra nie je veľké. Avšak IIP3 má hodnotu +28 dBm a potlačenie nežiadúceho pásma -70 dB.

The income is in the range of 100 kHz to 30 MHz, broadcasting 3500-4000, 7000-7300,10000-10150, 14000-14350, 18000-18200, 21000-21450, 24800-25000, 28000-29700 (KHz). Fashion: USB, LSB, CW, CW-Reverse, RTTY (45), PSK31, FT8 (including income and broadcasting directly from SBITX) and two-tone measurement signal for measurement IMD a PEP. Spotreba pri príjme do 1,5A, pri vysielaní 10A.

Prijímač má AGC, which was a feature that was missing the previous VU2ese TCVR. By TCVR-I is integrated raspberry pi, so súčasťou je aj denník s TX makrami, nahrávanie spojení vo WAV formáte či pripojenie na RBN a DX clustre priamo z sBITX.

Koncový stupeň sBITX využíva lacné tranzistory IRFZ24N. The full power of 40W reaches SBitx in the bands 80m and 40m, at 30m and 20m it is 30W, at 17m and 15m 20W. Even less, 10W is at 12m and 6W to 10m. Why? The amplifier chain in the transmitter starts with -15 dBM and ends with +46dbm. The profit of the amplifiers is dependent on frequency and therefore many designers avoid multi -band devices.

Part of the transmitter is also rečový procesor.

sBITX je ešte stále vo vývoji. Radio amateurs are helping to improve the TCVR by detecting shortcomings. So it is not yet possible to talk about the finished device, but it is likely that SBITX, like the other TCVR-E VU2ese, will find supporters. More on https://www.hfsignals.com/index.php/sbitx/