Well guys...this was better tonight. ?Made one contact WI1B 5x4 about 2310hrs. Only station loud enough to work. Only hearing partial calls from my /mm station. Might give a 40m hamstick a try next wknd. Just have to find the right combo on the water. ?Will try to be on wed night sm time and channel.?
73 Tom VE3THR?

开云体育

Has anyone used one of these to build a Raduino clone? ?If so, any issues I need to be aware of either hardware Sr software related?

Heard Tom and another station earlier, most likely John, but couldn't get back to either, still trying!

WS4JM

I heard Tom (VE3THR) for a moment or two, but the noise level is AWFUL!
--
John - WA2FZW

You got it! I do recommend the 3 position SPDT on-off-on switch idea, though, for the front panel control. Otherwise, Kees included those shorting plugs for you. You're Welcome! 73, Don

I have a spare stock Raduino. Email me....

73 Nick VK4PLN

I'm calling CQ on 7277 but have a S9 noise level here, so not sure I'll hear anything!
--
John - WA2FZW

Just so I got this, the 3 pin connector replaces the coax connections so the only other connections are the +5 Volts and the twisted pair from the volume control?? Looks like a very elegant solution!? I like being able to mount the board securely.

Thanks!

UBITX_CEC_Vxxxxx_16P.hex? : It is the LCD equipped with uBITX. Default LCD, 16x02 Parallel LCD This is the one you need

Sorry I cant help anymore as it works fine for me.

I did this of course.
I checked the box in the Ubit Manager on the PC, pressed encode and reuploadet it. Turned the radio off and on again. No change :-/

Thanks for sharing Mike. I found that most of my 2N7002's had about 10 pF output capacitance, the specs show up to 30 pF. Still not bad compared. I found that I got about 23 dB maximum attenuation with the shunt connection. Did you make a quantitive measurement? Hard to tell much from the audio clip but it sounded much like my first circuit (simple shunt). Makes for an easy mod, though! My next step was just to hang another 2N7002 across the output of first IF which added another 15 dB or so. The series element made the big difference, though. 73, Don

开云体育

Just to elaborate a bit: if you look at the datasheets for the different FETs above you can see that the output capacitance varies a lot from large size fets to small size fets. If the output capacitance is too high, you loose control over the AGC shunting effect / series resistance effect since ther will be lower isolation due to the capacitance.

You need to run Ubitx Manager on your PC.

Philip G7JUR

Hello everybody,

I just installed ND6Ts AGC Circuit and wanted to turn on the S-Meter in the firmware according to the instructions on
KD8CECs Homepage.
However I just can't get it on the display.

Whatever I selection of options I choose,? the only things i get on my standard 16x02 Parallel Display is

VFO A, VFO B, Mode, and tuning steps. I can change which VFO is shown first (toggling) or switch on (and off) rotation,
but I am not able to get my callsign or the S-Meter on the display.

The S-Meter signal is there - i checked it in the setup, ADC Pin7 gets read and a reasonable value is shown.

Am i doing something wrong? I thought first I may have accidently uploaded the 16x04 P Firmeware and reuploaded again -
this was not the case.

However according to the pictures (http://www.hamskey.com/2018/05/setting-smeter-to-ubitx-with-cec.html) there must be a way.

Any help would be appreciated.

Sascha, DL5SMB

I believe there is an nonlinearity problem on some of the newer V4 uBitx radios (the one with transistors in the final audio amp). Two of my radios had this problem.
The problem is that the two diodes in the final amp doesn't make a voltage drop that is larger than the drop over the BJT B-C junction drops, so there will be a crossover distortion problem.

I did a mod: cut the trace between the diodes. Soldere in a 500 ohm pot paralelled with the a 125 ohm resistor. I adjusted the pot from a low value and increased the resistance until the nonlinearity disappeared by listening to a moderately strong cw signal. I checked the lower transistor so it didnt become too warn from the quiescent current.

73s

The uBitx is prone to overload if there are strong signals. I have done some tests with an analog AGC detector and different FET shunts on the RX line after the relay before the first mixer.

I used a similar detector circuit as other people have published here. However, I used a BC548 as an audio amplifier instead as this is a very common bipolar transistor that is highly available with a high Hfe. The Hfe is approx 200x on the B series . The gain was set to approx? 200 in a common emitter amplifier. I take the signal from before the volume control. (Be aware that the volume control pot affects the impedance a bit so the level changes even if you tap on the hot side of the audio pot ... ). The detector is two 1N4148 diodes. There is a 1uF capacitor and a 1Meg resistor to set the first order RC circuit constant.

I tried with different FETs I had laying on the shack. Since this fet is used as a is a RF shunt circuit, it is not possible to use a JFET directly since JFETs are depletion mode.

By using an enhancement mode N channel Mosfet the RF shunt presents a high impedance to the AGC amplifier / recitifier. However, the output capacitance of the RF shunt Mosfet is a bit critial. I tried with a FQP30N06L (output capacitance in the 300pF range) and a IRLIZ44N (output capacitance in the 400pF range). Those presents a too low Z to the RF path since XC = 1/(2*pi*f*C). This is around 28ohm at 14 MHz, which will cause attenuation when the AGC is not active.
Instead I used a BSS138L N mosfet that I took of a level converter board I had laying around (I cut the board in four with the SMD part on to ease soldering). I soldered the mosfet controlled RF shunt directly to the relay pin and to ground on the back side of the uBitx circuit board instead of going in on the top side of the board as some other have reported on this forum. See pic.

Shunt mosfet for RF AGC:


The AGC seems to work well even with just one shunt element.




Testing with and without AGC: