Hi Mitchel,

My experience using the uBIT-X in FT8 mode is quite similar.

The uBIT-X has a remarkably sensitive receiver, on a good day I can "hear" FT8 signals from New Zealand (about as far as one can get from Belgium) at -24dB S/N.  Its transmitter is of course limited to QRP levels, I am typically running at 5...6W (continuous, not PEP) into a simple (not so good) 20m dipole. 

FT8 is a great mode inasmuch it gives a more or less objective measurement of the S/N on both sides.  Of the 100+ QSO I made during the past months the average difference between received S/N at my end and the received S/N at the other end is as much as 15dB (in favor of the other guy).  Some are as low as 0dB, some as much as 24dB.

Since the same transmission path, including both antennas, is used for both directions I come to believe that a lot of OMs are transmitting FT8 at 100...200W, levels, some even over 1000W.  Not entirely the intent of Joe Taylor with WSJT-X, but I am afraid it is one of these facts of life. 
It means that I don't even try anymore to make a QSO with a station that come in with a S/N of less than -10dB.  On good days I can still reach out to NE USA and Canada. 

73,  ON4JRT/Jean.

What is the emission type / signal characteristics of this "FT8"?

O meu uBitx v4, voltou a oscilar no 40m, 7074kHz em FT8, mesmo com "fake It" selecionado no JTDX. E observo a falta de potência de RF de saída na faixa dos 10 a 15m.

Translation using Google:
"My uBitx v4, oscillated again at 40m, 7074kHz in FT8, even with "fake It" selected in JTDX. And I notice the lack of RF output power in the range of 10 to 15m."

I believe that you are saying that you are getting feedback on 40m and low power on 10 and 15 meters.

I have found that FT8 transmissions tend to add issues with RF in the shack that leads to oscillations and distortion in the transmition.  This is because the power output is maximum at 100% duty cycle.  The only way around this is to reduce the RF in the shack with common mode chokes and to keep it from the input to the uBITX and Computer interface.  0.01 uF capacitors on the inputs, along with ferrite rings or snap-on sleeves help.

The lower power at higher frequencies is a known characteristic of the uBITX design.  There are hundreds of messages both commenting on and addressing the issue.  It is a tradeoff for the full HF coverage with a minimum cost that is the design point for the uBITX.  You can search the board for messages on balancing power across the bands.  In particular look for messages from Allison/ajparent1/kb1gma.

Above are my opinions.  Yours can be different and that is OK.
73
Evan
AC9TU

Portuguese Translation:

Eu acredito que você está dizendo que está recebendo feedback em 40m e baixa potência em 10 e 15 metros.

Eu descobri que as transmissões FT8 tendem a adicionar problemas com RF no shack que leva a oscilações e distorção na transmissão. Isso ocorre porque a saída de energia é máxima em 100% do ciclo de trabalho. A única maneira de contornar isso é reduzir o RF no shack com choques de modo comum e mantê-lo longe da entrada do uBITX e da interface do computador. Capacitores de 0,01 uF nas entradas, juntamente com anéis de ferrite ou luvas de encaixe ajudam.

A potência mais baixa em frequências mais altas é uma característica conhecida do design uBITX. Existem centenas de mensagens comentando e abordando o assunto. É uma compensação para a cobertura HF completa com um custo mínimo que é o ponto de design para o uBITX. Você pode pesquisar o quadro em busca de mensagens sobre o equilíbrio da energia entre as bandas. Em particular, procure mensagens de Allison / ajparent1 / kb1gma.

Acima estão minhas opiniões. O seu pode ser diferente e está tudo bem.