Hi, and thanks for the informations. I would like to say that my antenna is an attic dipole for 40m and I use 50 ohms coax. What I didn't said in the beginning is that I disconnected the display and I used some wires to connect it to the Raduino. But the Raduino itself is still in the original socket. Can it be this happening because of the display wires ? And somebody mentioned above about a capacitor of 0.1uF in the ADC line... should I put this in paralel or in series with ADC line??

Is this kit still available or did I miss it?

Thanks,?
Scott

A two tone test will check for IMD (intermodulation distortion, google it!).
It does not check for spurs or harmonics, which are the primary issues with the stock uBitx.

IMD can make your signal sound bad, and cause interference to those operating nearby on frequency.
If you have bad IMD, you will probably be told about it.
The stock uBitx with the mike gain set to a reasonable level will have enough IMD to be
slightly alarming when looking for it with a spectrum analyzer.
But the IMD products are way down (50dB or so) once you get a couple khz away.?
And thus it's a legal transmission anywhere AM phone is legal (at least with respect to IMD).
When transmitting at 5 or 10 watts, the IMD is probably not perceptible to someone using an adjacent channel.

If you have bad spurs and/or harmonics, you will be interfering with operations
on totally different frequencies.
For example, when operating at 28mhz, there's a? spur at 45mhz-28mhz=17mhz.

This particular spur is due to the 2*45mhz second harmonic of the first IF?
mixing with the high side clk2 VFO.? The VFO is always at 45mhz+DialFreq.
In this case, the spur is at? 2*45mhz - (45mhz+28mhz) = 45mhz - 28mhz = 17mhz.?

We also have a spur at 12mhz, due to crosstalk within the si5351? from the BFO at clk0
into the VFO at clk2.? This 12mhz energy on clk2 goes through the mixer at T2 unmolested,
and continues on through the transmit power amp and the transmit low pass filters.

Harmonics are simple integer multiples of the operating frequency.
For example, when operating at 7mhz, we get harmonics at 2*7=14mhz and 3*7=21mhz.
The transmit low pass filters at L11 through L22 should take these harmonics out,
but the stock uBitx relays (and to some extent, the board placement and routing)?
allow the harmonics to sneak past the low pass filter.

Also, for various reasons, we have some carrier leakage, though not too bad.
This results in a not quite suppressed carrier riding along with our SSB signal,
sort of like an AM phone signal.? Not really much of an issue at 5 or 10 watts,
but it does make our signal a bit wider than it should be.

Spurs, harmonics, IMD, and residual carrier are why you should think twice
before?adding a linear amp to the uBitx.
Like any rig without ALC (automatic level control), increasing the mike gain
too much (or shouting into the mike) will result in IMD.

The Bitx40 has a much easier job with respect to spurs and harmonics.??
There is a 7mhz bandpass filter before the transmit power amp, which knocks out all those spurs.
And with only one transmit low pass filter there is?no easy path for harmonics to leak out.
With too much mike gain it will have IMD, and there is some carrier leakage,
but these are relatively minor issues.

Jerry, KE7ER

I AM VERY NEW TO THIS. I DO HAVE A WORKING uBITX HF RADIO TRANSCEIVER.

I DO NOT KNOW MUCH ABOUT PROGRAMMING.? I HAVE A QUESTION.

HOW DO I GET THE FILE OR FILES TO DECODE THE MD AND UCO FILE EXTENSIONS?

I NEED TO KNOW THIS AND WHICH FILES ACTUALLY GET DOWN LOADED TO THE

NANO?


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The problem is with your Mic connection!

Raj

I have a Bitx40 which was built from the kit and has been functioning rather well.

For no apparent reason the TX seems to have a problem (no TX)
I connected a RF meter to the radio and noted that when I key the mike the needle jumps and straight back down.
This indicated to me that some TX power has been supplied but not continuious.
Subsiquent keying of the ptt do not have any affect
I have changed the Mike , incase it was faulty. (and whistled in it too)
I also have a spare main board and I replaced it, with the problem persisting.

Any ideas on what further I can troubleshoot or test

i spent 4 hours on ians site and github. downloaded a dozen or so files, could not get anything going from there. i will builds my project some more then try again.i may be looking too hard. didnt understand the whole CEC thing.
thanks again,
DAVE N4LKN

With standard gain settings I would not suggest it stock on FT8 which is a 50% run time.
With a small fan blowing over the stock heatsinks the output transistors get hot on FT8 after 8 cycles

I have two ubitx and it takes a minimum of about a 2x sized from normal heat sink and small fan The easiest test is to put your finger against the transistor after running it.

That said I have about 3-4x heat sinks and a ducted fan over the finals on my other ubitx and run 20 volts through the finals without any heating of the transistors. Well I am sure that there is heat but it is being dissipated It shows 20 watts power output on a mfj meter.

On FT8 the digital power level control works pretty good for controlling the final modulation.

Antenna matching is real important too. Even a 1.4:1 makes a difference in heating.

Happens in every country. However if you feel hurt and you are convinced they did not act properly you may have the possibility to report this to other departments so they may see to investigate internally. Keep calm and ... them politely!

Warren discussed this in detail. TX IMD are quite bad, however it does not sound bad at all. Keep in mind it splatters if you shout into the mike. I will try the VOGAD add on, at least it should deliver an almost constant mic input.

Nice to point out that existing pot. I suggest leaving it there, lift one leg and try a second pot in series on front or rear panel to trim the output power. Just he careful to route coax around the board so it does not compromise the filters or provide other unwanted leakage, I think this is the greater challenge.

I used the 1208 until I zapped the preamp. Also mine was an early one with a poor quality circuit board, but it could be restored if I ever have use for it. yes I had also thought 2 watts to be optimal drive.

Curt

You could add relays and pots to adjust power across bands.? I'm thinking about using the current system for 'max out' and a second layer for 'max 5W out' when feeding my WA2EBY.



Andy, KG5RKP

开云体育

Thanks for the feedback from all of you.

There is a strong broadcast signal on 7275 which is putting a fairly strong carrier on 7277.? Not good for weak signal work.?? Seems to me the calling frequency should be moved to someplace below 7200 and above 7175 to get away from the broadcast signals.? General class licensees can operate SSB starting on 7175.

Jim
W6yxy

I had the same problem.
(Well, at least I thought I did, turns out it was a PICNIC error).

Put the radio in CW mode, and find an AM station.

Hope that helps.

Dave - AI6K