John,
The v6 has the 3 pin connector, however, the power is coming directly onto the mainboard.? This is different than all of the prior version, where you comment is right on.? Not sure why they left the 3 pin connector, as the pins are jumpered together on the board.

FWIW
73
Evan
AC9TU

Leo,
Here is a video from Ashhar Farhan, the lead developer of the uBITX for HF Signals:


Note that you tune the BFO for low-frequency response to do the zero beat of an AM signal and then after the frequency calibration is set the BFO is adjusted back to have the highest response in the middle of the SSB filter range for audio that is between 330 to 3000 hertz.

So for the best calibration, you need to follow all 3 steps.

FWIW
73
Evan
AC9TU

Juan,
If your audio reports are coming back OK, then no problem, do not change anything.? However, the most impact for voice communication is in the mid audio range: 500 to 2500 hertz.? You might have the BFO set too low such that the SSB filter is allowing some of the carrier through and then cutting off the high audio frequencies.? Here is a video on the Calibration of the v6 uBITX.?


If you were to leave the BFO setup as in the first step, you would get more carrier bleed than when centered as it is designed in the 3rd step.? The first calibration of the BFO is to ensure that you get the low-frequency beat tones when doing the frequency calibration.? After setting the calibration frequency, you then adjust the BFO to bring the filter back centered on the 300 to 3000 hertz range for the maximum punch of the audio.

FWIW
73
Evan
AC9TU

Hello Aaron,

I would check the following in order:

1. That both the red and brown wires of the power supply connector are connected to the positive of the power supply. To double check i would measure the voltage on the tabs/ heatsinks of the finals (+ of power supply should be present).

2. The current consumption when pressing the PTT in SSB mode, no modulation, should go up to about 450mA indicating that the finals are most likely ok.?

73, John

开云体育

Aaron,
Verify that you do not have the "skewed pot" issue pictured in the following message:
/g/BITX20/message/73189

If that is the problem, then most likely you will have to replace one of the finals.? IRF510s are relatively cheap and readily available.

After the visual inspection, I would validate that the Bias regulator is delivering 5volts when the PTT is pressed and that there is a gate bias on each of the IRF510 output transistors.? All of this should be done into a good 50ohm dummy load rated for at least 10 watts.? The 20watt QRP-Labs dummy load is a good low-cost dummy load for up to 20 watts at only $8.50 plus shipping


The last test would be to readjust the bias on the finals to verify operation.? REMEMBER that the pots are REVERSED.? Minimum bias (current) is fully CLOCKWISE? You turn them counterclockwise to increase the current, being VERY careful not to exceed 150ma for each device.? Here is the HF Signals bias settings page:


If you can adjust the bias, then most likely the finals are OK.? The next most vulnerable device in the chain is then Q90.? This transistor has been know to be blown by nearby high power transmitters.? There is a recommended back to back diodes (1n4148 as an example) from the switched antenna lead on K1 pin 12 for the receive section to ground.? This will not affect receive sensitivity, yet protect when a high power transmitter keys up when in receive or powered down.

The above are just suggestions.? You should review the schematic and do the measurements to validate before making the mods.

Good luck hunting down the issues.
73
Evan
AC9TU

I received my uBitx a week and a half ago after DHL inexplicably held onto it for two weeks *after* I’d paid the import dues.?

Today I found the time to ‘build’ it. Half an hour’s work.

I’ve tuned the BFO but I can’t find any documents for configuring it otherwise.?

The rejection of noise on receive is unbelievable! Compared to my ft-818 on the same antenna (a 40/20 fan dipole @ 5m) it is *so* quiet.

However using that comparison I’ve noticed that the frequency is off 1500kHz compared to the Yaesu. That might explain my failure to make a QSO. How can I correct this? I only seem to have two menu options, one of which requires a 10000kHz signal the other tunes the BFO which I did using the page at HF Signals.?

Help?

开云体育

Yeah I had it in CW mode when I was testing it with the wattmeter. I do see the TX come on the screen when I push the PTT on the mic. I also hear the relay clicking when I push the PTT button. I do have a nicer mic, I don't know if it has a preamp or not built-in but I want to make sure that the rig works before I do any mods to it.?
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'72

Aaron,
First, don’t get discouraged.
Have you tried putting the uBITX in CW mode and pushing the PTT button on the microphone with the watt meter connected? Start out on the 80 or 40 meter bands first. Does the TX light come on? Can you heard a relay click?
Have you tried another microphone yet? I replaced mine with a CB microphone having a built-in preamplifier. It made a tremendous difference in power output for the phone mode.
I’ll let other folks chime in with more technical troubleshooting advice now.
Stephen

That looks awesome, makes me want a 3D printer!
--
'72

I have been wondering why I have not made a single QSO on my uBITX V6. I just assumed that it was bad band conditions, poor antenna, low power a number of things. I never really tried hard to get QSO's I just tried a little bit every now and then. This afternoon I hooked up a watt meter to it and sadly found out that it isn't transmitting at all. I checked the wattmeter on other rigs and it worked just fine. I put it back on the uBITX and nothing. So does this mean that I need to replace my finals before I get my first QSO on it??
I can't think of anything else, I hope that you guys have some ideas.?
--
'72

Since my radio always sits in the same spot I made a hold-down and because the stand makes the speaker angle away I also made an ugly sound deflector.




--
Lee - N9LO? "I Void Warranties"

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