I have this issue too, when The volume is down there is a buzz. It goes away a little when i turn volume half way, then comes back when i turn volume to max.

Joe
KD2NFC

On Mon, Apr 8, 2019 at 04:56 PM, Dennis Yancey wrote:

is it possible to buy a uBitx without the Raduino?

No, but raduinos posted for sale here have moved very quickly.
?
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is it possible to buy a uBitx without the Raduino?

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72 and God bless
KD4EPG

Here is a way to improvement the audio on the uBitx V5, connect a 10 micro F cap to the LM386 + to pin1 - to pin 8. solder to C75.
This will give a bit more gain, and bass.

Philip G7JUR

John

visibility appreciated.? it should behave like most v4's.? here is what I suggest --

take some CW data.? as its a different path, we found in measuring dozens of rigs that we tend to get harmonics on 40 and 30 meters especially, about 10 dB out of compliance +/-

then check the SSB data to see if you are getting a similar output power at the audio drive you are providing.? in our group session we have one of those classic HP audio generators that we can vary the audio level to find a sweet spot, and maybe back down just a little.? (we all realize we don't have ALC in the stock design).? many of us have issues on the 3 highest bands especially.?

if you have harmonic issues - one cure is using a daughter board with relays to replace? one side of the filters - it is working nicely in each ubitx that has tried this solution.? others prefer changing the relay - and possibly that might help with the non-harmonic spurs also I am understanding.?

I am confident the harmonic spurs are very fixable.? I am not so sure on the non-harmonic spurs - although my rig is clean now up through 17m on SSB.?

yes good idea to have some before deciding on your display and a matching case.?

Curt

Raj, ok mni tnx for your reply :-)

Farhan, also mni tnx for your reply :-) Okay, that'll be the first thing I'll check. But I didn't made any changes before - the drive pot is untouched so far;-)

73, Frank

?

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Iz

with these numbers I would speak softer into the microphone and be just fine.? important to see if they correspond to 'full' output power, if so I think most of us would be thrilled with them.? (but do check the harmonics also!)

a typical v4 uBITX has SSB spurs on 15, 12 and 10 meters that are too high for a tuner to confidently address.?

I am very curious about this data as I am not getting useful results with a added 45 MHz xtal filter stage.? If I figure out who is selling those shielded inductors in NA, I would be interested in them given this data.?

Curt

Indeed, they seem almost good results, especially on the 15m band, which was the most critical for spurs. Which version of ubitx do you have? If you use an ordinary (high - pass) tuner, you should be fine on 10m and possibly on 12m too. Thumbs up!

John

info appreciated.? I don't think you are likely using 50 volts audio -- maybe 50 mV ?? There may be more variation in the audio gain than RF perhaps.? I suggest you watch the output power as you adjust the audio, as producing an expected RF output tells us you are measuring spurs while simultaneously getting several watts of RF output.?

You didn't happen to say if this is v5 or a previous version?

I recognize that 12m spur being 5 MHz away -- mine has similar spurs almost equally below and above the carrier (one is a mixer spur, the other seems to be a signal passing through the mixer a second time (RF from PA leaking back into mixer input).? What you label as separation looks like you have subtracted the spur level from the main carrier?? By convention these are given as a negative value.? If you are outputting say 3 or more watts at 10m -- I really like your numbers -- they are 8 dB better than my v4.? Note your worst spurs are up there also, but yours are close to compliance - indeed if your rig is simultaneously outputting desired transmit power.?


The SSB spurs you are measuring tend to be a worse problem at the highest frequencies - I have non-compliant spurs on SSB only at 15, 12 and 10 meters.?

Also you need to seprately measure the worst harmonic.? Note these mostly impact bands at 20m and below, since the PA doesn't transmit as efficiently up above 10m where these spurs would land if they start at 18 MHz or higher.?

Be patient and you should get some good measurements.?

Curt

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I set up to do some SSB testing getting putting about 50Vpp in.
I don't know if I read the right peaks or not, but I looked for
the strongest signal that wasn't a harmonic.

Don't know how I skipped 17m, but that's life.? I'll do it next time.

I've replaced the relays and L5/L7.

Does this look about right or am I looking at the wrong thing?

It looks like no 12m or 10m based on spars or 80m due to harmonics for me at this point.

John
W1JDS

For those trying to follow the conversation, it started in this other thread:
? ??/g/BITX20/topic/30204401
Karl's adio had been working well as an SSB transmitter, but after trying to adapt it to a PC soundcard
for use on digital modes, it now has a strong residual carrier.
My understanding is that this undesired carrier is roughly as strong as the desired sideband.
Karl tried replacing the BAT54S diode pair in the modulator, that apparently did not help.

This fault may have nothing to do with the attempts at a soundcard interface,?
could just be from jostling and banging around the board.

Curious that the carrier is not getting at least somewhat suppressed by the 12mhz crystal filter.
I'd try shorting across R114 to disable the output from the modulator, then see if the carrier is still
there when the mike is keyed.? Could be that CLK0 is somehow getting coupled in after the filter.

Karl reports "At the C50/C63 node, I am getting?1.4 mV without the microphone being keyed and 1.2 to 1.5 mV when the microphone is keyed".
That node is going into the modulator from the mike amp.
Not clear if that is a DC level, or some sort of audio or RF AC.
If it's AC, that might just be local noise (perhaps from CLK0) getting picked up by a scope ground lead.
If it's DC, I would not expect that, but then I would not expect a mV or so to cause a very strong carrier.
Might be worth removing C50 and C63 from the board using two soldering irons, clean the board
in that area with alcohol in case some flux is providing a conductive path, then power up and see if
there is still a significant carrier when the mike is keyed.?
Check those caps with an ohmmeter to verify they are not leaking.

Perhaps windings on T7 have shorted out?
Might be worth rewinding T7 with new magnet wire, see if that helps.

Could replace that modulator with a commercially available diode ring mixer such as an SBL1 or ADE1.

One of the cheap AD8307 RF sniffers on ebay would be useful for looking at these?low level RF signals.?
Solder coax into the uBitx keeping signal and ground?as short as possible, run that coax into the sniffer.
? ??

Hacking at boards to investigate problems like this must be done carefully.
Would be very easy to create a second reason for this strong residual carrier.

Jerry, KE7ER

....and he fare (sic) prefers Linux.? ?

Jerry,

I have the v3 board as do you.? I bought 10 diodes from Mouser and installed a replacement (twice) this afternoon.? No improvement and still have the unsuprressed carrier.? I also heated up the pins on T7 to check for a cold solder joint, looked over the entire board with a magnifying glass to see if I missed something.? Loaded version CEC version 1.1 software, recalibrated, etc., without any success.

At the C50/C63 node, I am getting 1.4 mV without the microphone being keyed and 1.2 to 1.5 mV when the microphone is keyed.? I looked very closely at the microphone jack for bent pins and can't see any.

As before the radio works fine on CW and receives well.

Any other thoughts?

Karl - W5QJ

One other thing:

The MAX232 is just a logic level converter, between RS232 voltages and TTL/CMOS logic levels
The underlying UART protocol remains the same.
The UART protocol could be described in a paragraph.

USB is a different protocol all together, and ridiculously complex:
? ??
There's much more than logic level conversion going on inside the USB-to-UART devices.

USB is fine, so long as somebody else makes it work for me.
UART's are far simpler, easily debugged using?something like a $20 scope from JYETech.
? ??

Jerry

Yes it is printed. Never tried putting anything into the files section.