Date   
Re: ubtix_20 software errors #ubitx-help

MVS Sarma
 

Merle, Nothing I did to deserve thanks. may be some minor curruption in your file that resolved with a newer download.
  All the best .

Regards
MVS Sarma
 

On Tue, Apr 10, 2018 at 2:34 PM, <merle.spartan.63@...> wrote:
Thanks Sama, you solved my problem!  I downloaded the file again and saved in in My Documents\Arduino and then tried to compile it.  It worked!!!

Regards,

Merle
WA1JUP/G0DDZ


Re: W0EB/W2CTX Latest uBITX software release #ubitx

Chris Clarke G3SQU
 

Hi

I am CW only with straight key and am struggling to 100% understand from the release notes precisely how I should connect my key to use this firmware. At present I have the mono jack tip connected to the 'blue-4.7k-green' lead and it works OK, and I would prefer to leave it this way if possible (though use of the mic jack in order to free up the analogue port is tempting).  Could you advise please?

I will be fitting the I2C back-pack at some point, but for now I am still with the 'native' Raduino.

73
Chris G3SQU

Re: Raduino no longer recognized by PC

KB2HSH
 

Hey Jim...at this point, everything works. If I really wanted to worry about it, I'll order another uBITX for parts (not likely).  


John KB2HSH 

Re: uBitx just started transmitting a loud hum #ubitx-help

James
 

Thanks for the help - will test with 12v battery soon, but the power supply is working fine with my 100w rig on transmit - nil issues - so I'm not convinced the power supply has any major faults. Also the 3A fuse didn't blow when the tda2822 failed.

I've done some more probing with the oscilloscope and have some photos to add, both from the audio jack and from the collector of q70.


Audio jack - frequency measured by markers is 7.1mhz, approx 100mV amplitude.

FFT analysis of probe on audio jack shows major peaks at 546khz, 7.265mhz (largest), 21.6mhz, 36.0 and 43.1mhz.


PROBE on collector of Q7:




FFT shows peaks at 312khz and 2.9mhz at collector of Q70

I'm not sure if this makes it any clearer.
I couldn't reproduce the 50hz that I initially found - I think maybe it was just the ripple from the power supply being amplified in the audio amp from the vol pot wires (which I had moved whilst taking the measurements tonight).

Re: W0EB/W2CTX Latest uBITX software release #ubitx

Chris Clarke G3SQU
 

In the above I should have made it clear that my straight key presently works OK with my existing firmware (KD8CEC), as I have not yet tried the W0EB/W2CTX firmware, I might try it anyway but I don't want to start blowing things with incorrect groundings!

Chris G3SQU

 

Re: uBitx just started transmitting a loud hum #ubitx-help

James
 

Also re antenna - same noise present into antenna initially and into 50 ohm dummy load (which is what I have been using for all testing) with 1:1 swr into dummy load.
It is also present if headphones are unplugged. Still present with TDA2822 removed from socket.

PSU is adjustable voltage (I have set it to 11.8 in order to avoid frying the next TDA2822) and there is no sag on transmit.

Re: uBitx just started transmitting a loud hum #ubitx-help

James
 

Further investigations, and I'm pretty sure I've cracked it.
Probed Q6 collector - showing 4v swing at 50hz... No other 50hz anywhere else in power supply on scope.



I traced this to the mic output - which also shows 50hz - very low voltage however.
Re-examined the electret microphone and found low and behold a bit of the trace had lifted where soldered to my mic cable.

Having removed the electret element, there is no more loud obnoxious noise on Tx (albeit no noise at all).

I'll replace the electret with a new one and hopefully be back in business!

Once again, a great thanks to all the advice and help with potential sources of the noise!!!!

Re: Custom Graphics help for S-Meter

Vic WA4THR
 

After making some adjustments to the S-level thresholds, I am reasonably happy that the display seems to be tracking the S-meter readings on a commercial radio, so I uploaded the sketch and wiring to the files area.

=Vic=

Re: uBitx just started transmitting a loud hum #ubitx-help

Satish Chandorkar
 

I have seen failure of electret microphone in my BITX (Not uBITX) 2 3 times. In my opinion the biasing ( Supply ) resistance in case of uBITX 4K7 ohms is passing
high voltage spike ( Resulting instantaneous high current ) causing failure of the mic unit. May be even stray RF generated is causing these spikes and they are the
the cause of the mic failures

On Tue, Apr 10, 2018 at 5:41 PM, James <james.manion@...> wrote:
Further investigations, and I'm pretty sure I've cracked it.
Probed Q6 collector - showing 4v swing at 50hz... No other 50hz anywhere else in power supply on scope.



I traced this to the mic output - which also shows 50hz - very low voltage however.
Re-examined the electret microphone and found low and behold a bit of the trace had lifted where soldered to my mic cable.

Having removed the electret element, there is no more loud obnoxious noise on Tx (albeit no noise at all).

I'll replace the electret with a new one and hopefully be back in business!

Once again, a great thanks to all the advice and help with potential sources of the noise!!!!


Re: AGC circuit to try?

ajparent1 <kb1gmx@...>
 

Keys,

What not try a led and a CDS photo resistor.  I've used it and it works fairly well.
This comes from the olden days where we used a #49 bulb and CDS photoresistor.

FYI a bit of black tape or shrink tubing to keep external light out is suggested.

Allison

Re: uBitx just started transmitting a loud hum #ubitx-help

 

Just put a 470uF or more across C76 and see. There is a possibility that C76 failed, usually you would expect a bulge on the top but may
not happen.

All the higher frequencies you see on the scope will not be heard as a hum. The audio chip wont amp the higher frequencies other than audio.

OTOH somewhere I suspect a ground is open. That would explain the pics that you sent.

Raj

At 10-04-18, you wrote:
Thanks for the help - will test with 12v battery soon, but the power supply is working fine with my 100w rig on transmit - nil issues - so I'm not convinced the power supply has any major faults. Also the 3A fuse didn't blow when the tda2822 failed.I've done some more probing

Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

Tim Gorman
 

Thanks for the link.

They sell two different backpacks. One for $5 and one for $2. They look
like they use different chips.

I have a bunch of green on black lcd's that I have purchased over time.
My eyes just see green on black much better than any other combination.
The very first computer monitor I bought long ago was green on black
instead of yellow on black or white on black. I could just see the
green text on black the best. My opthamologist says he can't see
anything wrong in my eyes but the rods and cones just respond better.

Anyway, that's why I've been buying lcd backpacks instead of lcd's
already with backpacks.

The $2 backpack looks like the ones I have. I might give the $5 one a
try and see how it works. The code they give for it uses the pin
assignments although with a negative type instead of positive type.

tim ab0wr

On Mon, 09 Apr 2018 18:28:41 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

I'm not sure either.
I did have luck with one of these, though that was a year ago:
    http://www.oddwires.com/16x2-lcd-display-with-i2c-interface/

Not sure where they get shipped from, but they have an office in
California you could go picket if it doesn't work.  Also a phone
number.
That product page shows a "Hello World" script with the following to
initialize: LiquidCrystal_I2C lcd(0x27,16,2);

So they are recommending a library that does not require a list of
parallel pins like you guys are messing with.
They also state flat out on the product page that the i2c device
address can vary, then give a link to a script to scan for the i2c
address.

Jerry, KE7ER  

On Mon, Apr 9, 2018 at 05:10 pm, Tim Gorman wrote:


I'm not sure where one can buy quality, tested backpacks. I am now
leery of the ones from China.

Re: uBitx just started transmitting a loud hum #ubitx-help

 

Thats a big hum level at the mic out! Make sure the collector has no DC voltage.

Raj

At 10-04-18, you wrote:
Further investigations, and I'm pretty sure I've cracked it.
Probed Q6 collector - showing 4v swing at 50hz... No other 50hz anywhere else in power supply on scope.

Re: AGC circuit to try?

Tim Gorman
 

Jerry,

I have mine connected in the receive line before the first mixer. Your
idea might work better. I assume you would put it at the base of Q70 in
the ubitx?

tim ab0wr

On Mon, 09 Apr 2018 18:50:29 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

Ah, finally a reason why I keep seeing those photo-detectors in audio
agc schemes. Thanks!

Where did you have that 2n7002, at the top of the volume control pot?
I wonder if it would work better out in front of the audio preamp
where the signal levels are much lower.

Jerry, KE7ER

On Mon, Apr 9, 2018 at 06:29 pm, Sandy T wrote:


OK, well this one is still about AGC circuits........ 

I just built up the little AGC circuit which Ashhar Farhan
originally designed and it "sorta worked", but not well enough to
keep it in the product (distortion, levels, etc). The circuit uses
the second Audio output to generate a signal and feeds that back to
a 2N7002 for control ........seems like a good idea to me for a
simple Audio AGC. *However* , if you look at resistance developed
across the Source/Drain as the audio level changes, you will see
that for controlling an AC signal it's *not symmetrical.*  You
might be able to rectify this with a symmetrical bilateral
MOSFET ....but I haven't found one. 

I keep mentioning the OK Semiconductor H11F3M Photo FET
Optocoupler.....it has a *symmetrical bilateral silicon
photo-detector* and resistances look really good to me for AC
signal attenuation. Maybe someone can find a good symmetrical
bilateral MOSFET for $.02 ? 

73 Kees K5BCQ

Re: AGC circuit to try? new topic?

Tim Gorman
 

On Mon, 09 Apr 2018 17:56:57 -0700
"ajparent1" <kb1gmx@...> wrote:

We need a new topic!  this is not about AGC any more.

On Mon, Apr 9, 2018 at 03:23 pm, Tim Gorman wrote:


The 3rd harmonic of the carrier and the 3rd harmonic in a two-tone
test for this transmitter barely meet acceptable standards. I
wonder how much of this is from not being consistent with mixer
port terminations?
This would be normal consequence of both the mixers ( They are great
multipliers) and the Push-pull power amps ( they are better for
second harmonic but odd harmonics are not so good.).   Generally a
lack of adequate filtering is the major problem.  
Not much filtering you can do to help the 3rd order IMD product in a
two-tone test.


The transformer this is a red herring.  The impedance is not 200 ohms
e.  

 So I've never worried much about the high freq gain of the IF and
RF
transistors causing problems. Even the lowly 3904 and 2222 work pretty
well at 3mhz and 7mhz. <<<

Yes they do that very well.  How about at 21mhz (third harmonic of
the band frequency) and 53mhz/38mhz the 7mzh band and 45mhzIF  Lo
frequency? It will be at  the output of the mixer and the IF has to
terminate he mixer for all frequencies and their harmonics.  Then it
becomes important.  No better for the second mixer as then you have
12mhz and the LO at 33 or 57mhz... Even the third harmonic of 12 is
beginning to reach beyond.    A band pass or twin T diplexer at each
IF port can help with that by absorbing the out of band products.

The output has the following components even f perfectly terminated...
 For 7mhz...
I used a simple diplexer in my 80m/40m to terminate the mixer in my
last receiver. It worked well. Of course it was only a single
conversion to a 9Mhz IF with a 9Mhz BFO. In the ubitx the 45Mhz filter
and the 12Mhz filter should help stop many of the birdies from the
mixer products. But those birdies also impact the rest of the chain.
With no filter on the inputs to the amps who knows what the amps are
actually doing.


7mhz,  (includes 14, 21, 28...)
LO either 53 or 38mhz, (106, 159, 212 or 76, 114, 152) 
The IF 45mhz,
The sum of their individual harmonics mixed with all the possible
harmonics and their sums and differences.  any product that results
in 45mhz makes it though the filter but after the amp whose IMD at
higher frequencies is poor.

This is endemic with DBMs and represent the dark side of a easy to
plug in function.
This is probably more important on the transmit side than the receive
side but even on receive they can contribute to the noise.


Also the input the the DBM should be kept about 10db lower than the
LO power for a reasonably clean output and to avoid compression with
higher IMD.  There is more than enough gain to saturate the first and
second mixer if the mic gain is too high.  People rarely hear that
when tuned to the output frequency but a spectrum analyzer sees it as
well as adjacent frequencies in band.
Which is why the two-tone IMD product is just acceptable instead of
being good.



And the transmitter....  Its not clean not solely because the input
is possibly loaded with products from the mixer but you may want to
view the amplifier chain with a closer eye. That would be easy to
clean up with a band pass filter at the input of the power chain and
lots of band switching.  The IRF510 at 12V is legendary for it
non-linear behavior. Its value is availability and price not the
quality of the signal it can generate.  FYI at 24V it actually
improves and produces more power as well.    For that fact the
RD16HHF is not that much better when compared to a 28 or 50V power
LDmosfets. Most bipolars at 12V are only ok as well when compared to
the higher voltage parts. The parallel bipolar drivers are on the
weak side as well.    T
I adjusted both the drive level and the bias of the IRF510's for the
best possible 3rd order IMD and it is still just barely acceptable. I
haven't tried more than 14v on the IRF510's. I have a nice 24v
transformer I could a power supply from. I might try that someday. I'm
not really interested in running more power since this is supposed to
be a go-bag emergency unit for me to use on traffic nets. But if the
IMD could be improved it would be a change for the better. The problem
would be finding a 24v battery in the field!


tim ab0wr

Re: AGC circuit to try?

Jerry Gaffke
 

It was just a thought, getting an AGC scheme to work well is not trivial.
I'm still thinking a BAP64Q at R17 might be best.

Base of Q70 could work.  It might do better on the other side of C50, where that weak
incoming audio is centered on ground. 
Though as we have seen here, have to think about what happens when you have
strong audio from the mike amp during transmit, potentially going through
the intrinsic diode in that FET. 

You're on your own!

Jerry


On Tue, Apr 10, 2018 at 07:32 am, Tim Gorman wrote:
I have mine connected in the receive line before the first mixer. Your
idea might work better. I assume you would put it at the base of Q70 in
the ubitx?

Re: uBitx just started transmitting a loud hum #ubitx-help

Michael Shreeve
 

Any measurements of current ? Did you have a fuse ? I'm thinking the audio circuit had an extreme amount of audio, oscilation or something like that. . You didn't say you could hear anything, so perhaps you also had a shorted output, perhaps at the jack ? If the jack is set up incorrectly you will short out the amplifier. Remove  the jack from ground .. Combination of problems ? 

Re: uBitx just started transmitting a loud hum #ubitx-help

Michael Shreeve
 

My mistake, you did say you heard a loud hum. So, current measurement would be a good start. 

Fw: Re: [BITX20] Raduino no longer recognized by PC

Jack, W8TEE
 


Another common problem is a faulty bootloader. Sometimes you need to change the processor selection (Tools --> Processor --> ATmega328P (old bootloader)). Also, many of the clones use the CH340G chip for the FTDI. Usually you can google "Arduino CH340G driver download" and find one for your op system:



There's nothing wrong with the clones, but when you produce and sell them for under $5, sometimes they take shortcuts over the original circuit.

Jack, W8TEE


On Tuesday, April 10, 2018, 5:14:39 AM EDT, Jim G4GNO <jim@...> wrote:


Hi John,
I think the clone Nano's have a few quality issues.  My uBITX Raduino Nano had a dodgy USB socket.  The Nano would  be recognised on a PC if the cable was pushed in hard but would fall out again with even a small movement. I got round it by installing a short USB B to case socket extension cable and fixing the Raduino end so it could not move around. 

Jim

Fw: Re: [BITX20] AGC circuit to try?

Jack, W8TEE
 

For a keyer in the Projects book, we used a 4n26 optoisolator between the keyer and the keyed circuit. Mouser and Digikey sell the chip for $0.60.

Jack, W8TEE


On Tuesday, April 10, 2018, 9:56:01 AM EDT, ajparent1 <kb1gmx@...> wrote:


Keys,

What not try a led and a CDS photo resistor.  I've used it and it works fairly well.
This comes from the olden days where we used a #49 bulb and CDS photoresistor.

FYI a bit of black tape or shrink tubing to keep external light out is suggested.

Allison