Re: How hot is too hot?

Jerry Gaffke

My Raduino with display draws 0.100 Amps.
Voltage drop across your 47 ohm resistor would be 47ohms * 0.1amps = 4.7 volts.
Assuming a 12v supply, that leaves 12-4.7 = 7.3 volts at the LM7805,
which gives it the required headroom of 2 volts over the 5 volt output of the LM7805.
Power consumed by the resistor would be 0.1amps * 4.7volts = 0.47 Watt.

How hot is your 1/4 Watt resistor?
I'd suggest at least a 1/2 Watt resistor if sticking with 47 ohms.
Or a 25 ohm 1/4 Watt (better, 1/2 Watt) resistor, then the LM7805 will stay in regulation
down to a power supply of  5.0v+7.0v + 25ohms*0.1amps  = 9.5 volts.

The LM7805 can get hot enough to sizzle spit and still not be breathing hard:
https://groups.io/g/BITX20/message/47859

But the IRF510's while also rated for a 150 degrees C junction temp, should never
have tabs so hot that you can't keep your finger on them:
https://groups.io/g/BITX20/message/47871

Jerry

On Wed, Jun 13, 2018 at 08:54 pm, Skip Davis wrote:
Bo I found the same thing what I did was to add a 47 ohm resistor in the 12vdc into the regulator. I added it on the Raduino board and now I can hold my finger on the regulator without burning my finger. I just cut the trace from pin 15&16 on the Raduino and wired in a 1/4 watt resistor.

Re: How hot is too hot?

Bo Barry <wn4ghv@...>

Thanks for all the inputs! I've done lots of work with the regulators over the years. One comment I can add to this excellent discussion is that the output ripple increases badly as the voltage difference approaches 2 volts.  Zener diodes are horrible at their 'knee' to.
Being old fashioned I always thought if I couldn't count to 10 touching something (electronic only) it needed a heat sink. 🤔.    When I converted 50 degrees C, which is OK I stopped counting to 10.  The 150C idea scares me.
The big Radio Shack heat sink works great.
I had extensive college coverage (with the math) of heat sinks, mica and grease, etc. Loved the math.
BTW the TINY 5v fan does great for WSPR & FT8 duty cycles. I even put my tongue on the finals. 😂.  Thanks for discussion.

Re: ic2 display problems #arduino ???

Jack, W8TEE

I'm not sure, but I think the I2C interface expects to use A4 and A5 for the interface. One of the hardware guys can help you there.

Jack, W8TEE

On Thursday, June 14, 2018, 11:09:34 AM EDT, Bill Watkins <kf7yxs@...> wrote:

Thank you very much.

Another question; should the original display still be enabled even though ic2 is programmed?  Not used at same time, but when swapped back the display acts as originally shipped.

73,

Bill
K0WHW

On Jun 14, 2018, at 09:43, Jack Purdum via Groups.Io <jjpurdum@...> wrote:

Have you tried the display with one of the examples from the library just to make sure that you've 1) got a working display, and 2) it's wired correctly. Often a problem is that there are numerous LiquidCrystal libraries and they are substantially different. Unfortunately, Dr. Lee didn't follow the convention that gives the download URL for the library on the same line as the #include. That suggests to me that he's using the library that is shipped with the Arduino IDE. Check any examples that your manufacturer has to see if they give the download URL for the library. Also, there is a library for I2C LCD's:

You might give that a try as I don't think the standard IDE library is for I2C displays.

Jack, W8TEE

On Thursday, June 14, 2018, 10:24:35 AM EDT, Bill Watkins <kf7yxs@...> wrote:

Hello,
I have attempted to duplicate Ian Lee’s success. 1) I have latest firmware and manager. 2) tried 0x27 & 0x3F; neither makes a difference. Display manufacturer says 0x27 correct. 3) Checked voltages on bcc, sda, and scl; 4.48, 3.89, & 3.90 respectively.  4) display lights up and separate, new display lights up. No letters in either regardless address used. Unit still works and original display still works with ic2 settings when swapped back.

Anyone???!

Jerry Gaffke

Hans,

By all reports, the QCX is a great product at a great price.
And we appreciate the care you have taken to document this and your other products.

I'm curious, have you measured the increase in jitter when going to a fractional output msynth on the si5351?
Not clear to me whether or not this is a significant consideration for the uBitx.

While AN619 does recommend holding it in integer mode for minimum jitter,
the si5338 docs (a sister part that is better documented) suggest the increase in jitter is well under a factor of two.
Also, I have found that ClockBuilderPro from SiLabs leaves the output msynth in fractional modes, but does
an exhaustive search for an a+b/c with small values for b and c.

Another issue, the uBitx uses all three clocks out of the si5351, and with only two PLL's available in the si5351
it's at least bothersome if not impractical to keep all three output msynth's in integer mode.
I agree that you must be in integer mode to use the phase shift feature to get quadrature clocks, but that
is not a requirement on the uBitx.
(Very nice to know that the vco can work well beyond the 600-900 mhz spec, thanks!)

We could, however, use PLLA on clk2 as you suggest, with an integer output msynth.
Choose the PLLB frequency based on the required (mostly fixed) frequency of clk1 into the second mixer,
so this could also have an integer output msynth.
The bfo on clk0 is only at 12mhz, so could use  PLLB) along with a fractional output msynth.
At 12mhz versus a maximum vfo frequency of 30+45=75mhz, the jitter of this bfo will be far less than
the vfo in spite of the fractional output msynth.

But this would complicate the si5351bx routines considerably, also increase the amount of flash used.
Unless jitter is known to be an issue on the uBitx, I am inclined not to bother.
A better fix might be to build a Raduino that uses the lower jitter (and lower crosstalk) si5338,
especially for those wishing to extend the uBitx for use as a VHF rig.

Jerry, KE7ER

On Thu, Jun 14, 2018 at 07:29 am, Hans Summers wrote:
Hi Miguel, all

I saw in the English Google translation of you web page that you had questions about how to get down to 3.2MHz with the Si5351A configured in Quadrature LO. The answer is that you must abandon the 600-900MHz limit on the Si5351A internal VCO. The lower limit at which you can configure the VCO is something like 400MHz (I forget the exact number), and 400MHz / 126 = 3.2MHz.

Three requirements for a silky smooth, click-free, quadrature LO that tracks at precisely 90-degrees across the whole band as seen in the QCX 5W CW transceiver http://qrp-labs.com/qcx are:

1) Set the MultiSynth division stage to an even integer between 4 and 126. Set the phase offset register to the same number. And leave them, don't alter again, unless you make a huge frequency change (e.g. 10MHz) and find you need to change the MultiSynth division again. Configure the first stage, the VCO PLL, with a fractional divider. Note that this is the OPPOSITE way around to the NT7S library which uses a fixed integer up-multiplication to the VCO, then a fractional MultiSynth division in the second stage. Quadrature LO cannot be obtained unless you fix the MultiSynth divider stage to an integer, and vary the PLL (VCO) for the actual frequency changes. In any case, the SiLabs documentation recommends even integer divider for the MultiSynth stage for lowest output jitter (phase noise). Therefore it's a good idea to do it this way, anyway - even if you aren't looking for a quadrature LO.

2) Do NOT do a PLL Reset (by setting the PLL Reset register bits in the Si5351A) at every frequency change! Only do a Reset when you change the MultiSynth Divider. Here, the reset is absolutely required in order to set up the initial phase relationship correctly between the two outputs. But you do NOT need a PLL Reset subsequently when you change the frequency, even when you change the frequency by a substantial amount. Doing a PLL Reset WILL create loud audible clicks.

3) Do NOT be tempted to try to switch off Si5351A outputs during frequency changes. It also generates clicks (albeit lesser ones). It is a bad solution to the problem of clicks, because it does not tackle the real problem (unnecessary PLL Reset commands), it only masks the problem slightly. As long as you heed my advice in 2) above you will never need to temporarily switch off Si5351A outputs.

These lessons were all learned the HARD way over the last three years, during QRP Labs products firmware development (and evolution). Unfortunately there was no easy way, due to the poor SiLabs documentation. Now the easier way is to learn from others' mistakes :-)   (a.k.a. MINE). All of this is described in more detail in my Dayton FDIM 2018 seminar accompanying article, the PDF is available here http://www.qrp-labs.com/dayton2018.html

73 Hans G0UPL

Re: Strange tuning issue

Jerry Gaffke

Calibration.

If you are using stock firmware, it should arrive calibrated.
Sounds to me like your BFO frequency is not properly aligned with the passband of the 12mhz crystal filter.

Unfortunately, as you adjust the BFO in the stock firmware, the radio does not adjust the VFO to keep the station tuned in.
(I believe that is the case, it has been months since I have messed with the stock firmware.  And new units might
have different firmware now.)
So adjust the bfo until you hear audio coming through in the voice band frequencies of roughly 300 to 2300 hz,
even though the transmission remains unintelligable.  Save that bfo setting, and try the radio.

You may find that there are two settings of the bfo with the desired 300 to 2300 hz audio content,
one for LSB and one for USB.  Only one of these will give intelligible results.

The code I now have uses the tuning algorithm here:
https://groups.io/g/BITX20/message/44278
This makes setting the bfo, and setting the passband centers for the
45mhz and 12mhz crystal filters fairly trivial and intuitive.
Calibrating the 25mhz reference for the si5351 is carried out as in this post:
https://groups.io/g/BITX20/message/35235
A description of what is going on is here:
https://groups.io/g/BITX20/message/44515

I don't know if other firmware releases have picked up on this.

Jerry

On Thu, Jun 14, 2018 at 07:52 am, jocarl011 wrote:
Hi, I have just completed the ubitx and put it into a metal case. Everything is working fine except when I try to tune in any station! When a few khz off on ssb the signal is coming in loud and strong until i start getting closer to tuning in the station and they just seem to fade away to almost nothing! When I’ve tuned the station in they are very quiet and barely audible?

Any idea what could be wrong?

Re: First Mod to µBitx = first screw up--Oh my

Don, ND6T

No worries! Small coax like RG174 is highly suggested. Yes, your workaround is good, don't worry about the stray traces at these frequencies. Use your ohmmeter to insure that you have the right pins.
I believe that there was an excellent post a few months ago that showed the pin numbers. Perhaps someone can help before I can locate it?
As for shaking, I know of what you speak! The best answer is practice. Firearm enthusiasts have the answer, though: Bracing. Get your work down on the bench top and use both hands, arms tightly wedged. Hold your breath. Time your actions. And if you have a medical issue like I do, avoid stress and wait for a good day.
Take your time. Remember what the radio costs. Just have fun. Worst that can happen is a week or two for a whole new radio. 73, Don

Re: First Mod to µBitx = first screw up--Oh my

Jerry Gaffke

Here's that excellent post  from AA9GG with the pin numbers for the uBitx and Bitx40 relays:
https://groups.io/g/BITX20/message/47000

The relay datasheets number the pins as if the device was a 16 pin 300 mil wide DIP.
(The TDA2822 is an 8 pin 300 mil wide DIP, where DIP means "dual inline package")
But skips over some of the pin numbers because relay pin spacing is 200 or 300 mils instead
of the standard 100 mils.

Also, the uBitx schematic has pin numbering a bit different than the relay datasheet,
has the relay rotated 180 degrees.

Jerry, KE7ER

On Thu, Jun 14, 2018 at 09:07 am, Don, ND6T wrote:
I believe that there was an excellent post a few months ago that showed the pin numbers. Perhaps someone can help before I can locate it?

Re: First Mod to µBitx = first screw up--Oh my

Clark Martin

I believe that is due to some datasheets having the pin numbering rotated 180 degrees as compared to other datasheets.

Clark Martin
KK6ISP

On Jun 14, 2018, at 9:15 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Also, the uBitx schematic has pin numbering a bit different than the relay datasheet,
has the relay rotated 180 degrees.

Re: Ubix & case for sale

Dave Dixon

HEY UP CHRIS,
ITS DAVE G0AYD,lost your phone number when my phone shit i8tself and deleted all my contactstrust tour well..tried to ring you but no responce.heres my my mobile 07735944744.wonder what version the mbitx is and can you send me pics plrase,im interested,regards dave

On 14 June 2018 at 01:50, chris gress wrote:
I am selling my Unix untouched kit and untouched case both boxed case came from sunil lakhani is red UK will ship to euro land if postage covered selling for what they cost me £123.27 post free in the UK contact chris g0wfh tel 07482429329
Email chrisg0wfh at gmail . com to much work and no time for the kit thanks chris

Re: How hot is too hot?

Allen Merrell

Mine in the oem state with 16x2 display never got too hot to hold. went to 20x4 display and it got HOT too hot to hold added a Nextion 3.2 enhanced and it got even hotter so I am considering building an auxiliary 5v supply off the 13.8v input line to run what addon's I add to it to get this load completely away from the raduino board.
73's  kn4ud
--
Allen  Merrell

uBitx has a bit too crispy / semi-distorted audio even on low signal levels

Mike

I have completed the uBitx and calibrated both frequency and BFO. The sensitivity appears OK. However audio has a strange crispy / semi-distorted sound to it.

I read the post from W3JDR https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/#comment-1507  about biasing Q70 more strongly, however that only reduced the gain somewhat but didnt seem to help the crispy / semi distorted sound.

I have tried several headsets and a speaker. Same issue.

Anyone have any hints to what may be done to achieve better audio and get rid of that distortion effect?

Re: How hot is too hot?

Bo Barry <wn4ghv@...>

I put a handy buck converter that has a voltage display on it and dropped the voltage to 8 volts with it, AND LABELLED THE PLUG.
Currently using it with the addon arduino/display, but might incorporate it to the ubitx built in display.

Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels

KE6BB

Are you sure you have the BFO set and fine tuned?   Check out VK3YE's YouTube video to see how he fine tuned his BFO setting:

https://youtu.be/sXJmAhpAjeI

He is listening to his transmissions, but if my memory hasn't failed me, the setting affects both TX and RX.

Hope that helps.
--
Mark,
KE6BB

Re: How hot is too hot?

Jack, W8TEE

Our 5" TFT color display can draw as much as 0.7A @3.3V, so we're working with a pretty hefty buck converter.

Jack, W8TEE

On Thursday, June 14, 2018, 1:18:25 PM EDT, Allen Merrell via Groups.Io <kn4ud@...> wrote:

Mine in the oem state with 16x2 display never got too hot to hold. went to 20x4 display and it got HOT too hot to hold added a Nextion 3.2 enhanced and it got even hotter so I am considering building an auxiliary 5v supply off the 13.8v input line to run what addon's I add to it to get this load completely away from the raduino board.
73's  kn4ud
--
Allen  Merrell

Re: How hot is too hot?

ajparent1/KB1GMX

One of the big power consumers in the Raduino is the backlight for the display.
Before I tamed mine it was over 80ma!  At 20ma it was easier on the eyes.

Allison

Voice keyer - parrot - ISD1820

iz oos

Hi, what about using cheap ISD1820 voice recorders kits as voice keyers? They seem to me they have a really high output, something like half a watt on a 8ohm load. If they can be used would a audio transformer 8-1000ohm really needed or would just unnecessarily elevate the voltage without any benefit? Would a 1:1 audio isolation transformer a better choice. How much attenuation would be necessary to prevent any damage of the mic input of the ubitx?

Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels

Ralph Mowery

My receive and transmitted audio did not have much highs or lows in it.  The filter was only about 1700 Hz wide.  I changed the 5 capacitors from the crystals that are used for the filter from 100 pf to 82 pf ( think that is the standard value) and it widened out the audio range .  Probably should parallel some 5 or 6 pf capacitors across them to get about 85 to 88 pf as I did not have anything between a low 80 and the 100 pf.

That effects both the transmit and receive response, so you may want to make sure the transmit audio sounds about the same.

de ku4pt

On Thu, Jun 14, 2018 at 1:18 PM, Mike wrote:

I have completed the uBitx and calibrated both frequency and BFO. The sensitivity appears OK. However audio has a strange crispy / semi-distorted sound to it.

I read the post from W3JDR https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/#comment-1507  about biasing Q70 more strongly, however that only reduced the gain somewhat but didnt seem to help the crispy / semi distorted sound.

I have tried several headsets and a speaker. Same issue.

Anyone have any hints to what may be done to achieve better audio and get rid of that distortion effect?

_

Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels

Jerry Gaffke

If the audio is loud enough and has sufficient bass and treble and an SSB transmission is intelligble,
then this is not likely a BFO issue.  Could be a fault most anywhere between the antenna port
and headphone jack.   Though I would expect this problem to be somewhere from the demodulator
on through the audio amps.

I would probably first try injecting a low level audio signal into the bottom of C50.
power level by a factor of a million or so (60 dB) first to avoid over driving Q70.
That means a voltage ratio of sqrt(1000000) = 1000  so from headphone jack to a 1 meg resistor
to a 1k resistor to ground, add a wire from the top of the 1k resistor to the bottom
of C50.  You also need a ground connection.  If that sounds good, then trouble is further back in the radio.
I'd look very hard at the demodulator if it isn't in the audio stages.
Trouble in the RF sections of the radio might mean birdies or weak signals, not so likely to
create distorted audio.

Not sure anybody here knows what objectionably "crispy" audio sounds like,
you might give a link to an audio recording.

If there's another uBitx or Bitx40 in the neighborhood, you could patch in a signal from that other
point of that other radio, if the receiver now works well that means the fault is closer to your antenna jack.
Ideally remove c30 from both rigs, then have a 0.1uF cap in series with the
signal wire from one rig to the other to keep impedances about where they should be.  That wire is
ideally a piece of 50 ohm coax, ground both ends of the coax braid.

Good luck!

Jerry

On Thu, Jun 14, 2018 at 10:18 am, Mike wrote:
I have completed the uBitx and calibrated both frequency and BFO. The sensitivity appears OK. However audio has a strange crispy / semi-distorted sound to it.

I read the post from W3JDR https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/#comment-1507  about biasing Q70 more strongly, however that only reduced the gain somewhat but didnt seem to help the crispy / semi distorted sound.

I have tried several headsets and a speaker. Same issue.

Anyone have any hints to what may be done to achieve better audio and get rid of that distortion effect?

Re: #ubitx-help

hakan.sjostrom@...

I have got help for my RX problems. But nothing of what I could though about. In my home I hear a lot of signals with my little transistor radio but nearly nothing with the ubitx. At my friends house suddenly there was a lot of signals with the rig (and a dipole antenna). I also tested the LW at another place outdoors - no problems. So it seems the problem is in the enviroment of my apartment (combination with the indoor antenna?)
Anyway it looks a lot better now. And many thanks to you who tried to help me with my problem!
Håkan

Re: Latest Build, Mods and results.

Mike

Hi @Mharpen do you have a shematic of the audio amp circuit you used to compensate for the gain loss of the AGC circuit?