Date   
Re: I did it again.. i plugged the arduino pins on reverse

Arvo W0VRA
 

On Tue, Jan 30, 2018 at 01:10 pm, César EA3IAV wrote:
If you don’t understand something you may ask. Not to mention English is not my first language. But it is easier for you to make a compilation of my clumsiness.
Jerry is asking, and he's not making a compilation of your clumsiness.  He is, however, making a compilation of all the issues you have had with the radio to get a thorough understanding of what might be causing the trouble.

The situation is complicated and the symptoms you describe are confusing.  Blowing a regulator on the Raduino is very odd.  Losing the connection between the 3V3 and C1 on the Raduino board is also very odd.

Re: uBITX woes, feeling disheartened. #ubitx

César EA3IAV
 

I may want the raduino board James ...

Re: Message authorization

M Garza <mgarza896@...>
 

Here is a link to Allard's software.
 The instructions are on that page.

Marco - KG5PRT 

On Jan 30, 2018 3:24 PM, "john robertson" <kk6gkradio@...> wrote:
Greetings, will you allow me to send messages to the group?  I have a working BITX40 but could use some help in updating the firmware.
Thanks,
John Robertson

Re: Message authorization

Arv Evans
 

John

I could join you to the group but would not know the configuration you might
want for the subscription.  It would be better if you were to go to the group
site and do your own subscription.  There you can fill in your email, message
preferences, etc. 

  https://groups.io/g/BITX20

  https://groups.io/g/BITX20/editsub

Arv  K7HKL
_._


On Tue, Jan 30, 2018 at 2:24 PM, john robertson <kk6gkradio@...> wrote:
Greetings, will you allow me to send messages to the group?  I have a working BITX40 but could use some help in updating the firmware.
Thanks,
John Robertson


Re: IRF510 amplifier failures

William Kimber
 


What many people fail to realise when using a diode bridge for reverse polarity protection is it means neither of the power wires are at ground potential.  If used in vehicle with battery having one terminal grounded the grounds are not at same potential.  So your metal case and vehicle body have a diode drop difference.


Cheers,

Will

ZL1TAO


On 31/01/18 06:05, Jerry Gaffke via Groups.Io wrote:
<SNIP>
Reverse DC is not a problem for the IRF510.  It has an intrinsic reverse diode from source to drain,
will blow the traces or coils between it and the power supply.  Or, with some foresight, the fuse
you put into that power supply lead.  Where you need reverse protection is going into the remainder
of the board, be it Bitx40 or uBitx.  A 1n4148 diode would suffice, a 1n400x would not get quite so hot,
but there is no problem with running all that stuff at 0.7 volts less.  

Having a full wave rectifier in line with the power supply to the IRF510's would reduce the voltage
there by 1.4 volts.  And have a significant hit on output power available.

<SNIP>
On Tue, Jan 30, 2018 at 04:54 am, John Brock wrote:

I have not received my uBitx yet. I’ve been  reading this forum for about two weeks. Looks like PA failures is a huge problem.

Are the two main causes reverse DC power and high SWR?

For the DC polarity problem how about a full wave rectifier at the DC input? Two diode voltage drop a problem with this approach?

What would be the best way to limit PA  power out to a very small value to allow a manual tuner to be used for the SWR issue?

 


Re: I did it again.. i plugged the arduino pins on reverse

Jerry Gaffke
 

I can deal with the language barrier.
Podemos emplear espanol si quieres, pero no he practicar lo unos veinte anos.

You do have to describe what is going on in detail if we are to fix this through forum posts.
Otherwise you will have to find somebody there to help you in person.
But I think I understand your situation now.


You have a uBitx, the only complaint remaining is that when you press the PTT switch
it does not go into transmit mode.  No clicking from the relays. 
I assume the uBitx continues to receive with PTT pressed.


Check these points of the uBitx with a voltmeter, measuring voltages to ground:

When you press the PTT switch, the orange wire into pin 5 of the 8 pin connector into the Raduino
should go from high (about 5v) to low (about 0 volts).
    http://www.hfsignals.com/index.php/ubitx-wire-up/

The Nano on the Raduino sees that low from the PTT switch and responds 
by driving the T/R pin high into the uBitx main board.
The voltage at the top of C150 as seen in the lower left of the uBitx schematic goes from 0 volts to around 5 volts:
Here's the uBitx schematic:
    http://www.hfsignals.com/wp-content/uploads/2017/12/ubitxv3.pdf

The 5 volts at signal T/R turns on transistor Q15, which will make pin 9 of relay K1 go from 12 volts down to near 0 volts.
With the coil of relay K1 now energized, K1 pin 3 should go from 12 volts to zero volts to remove power from the receive circuits
and K1 pin 5 should go from zero volts to 12 volts to power the transmit circuits.

The pin numbering of the relays is kind of funny, it is numbered as if it has 16 pins,
but some of the pins are missing.  Here's the view from the bottom of the board.
Pin 1 has a square pad:

16    1
X     X
14    3
X     X
12    5
X     X
X     X
9     8    

Best Regards,
Jerry,  KE7ER



On Tue, Jan 30, 2018 at 01:10 pm, César EA3IAV wrote:
Don’t worry. I will not make you read anymore. I thought It was clear what I explained. If you don’t understand something you may ask. Not to mention English is not my first language. But it is easier for you to make a compilation of my clumsiness. Radio works and receives but ptt is not working. No relais noise. No swiching.  Somehow despite of all connections seem to be good as i teaces continuity. That wire was the only execption I did to make sure there is a connection between that pins I described.

New case found

Richard E Neese
 

Re: New case found

Richard E Neese
 

Re: New case found

M Garza <mgarza896@...>
 

Looks like the one I am using for my ubitx.

Marco - KG5PRT 

uBITX AGC - Adafruit TPA2016, A Success! #ubitx

Nick VK4PP
 

Hi Group.
Now, I haven't tried many AGC solution on the uBITX, only 2, the VK3YE, and ADAFRUIT TPA2016 I2C module.
The VK3YE solution I found messed with the audio quality, made it all scratchy, and still didnt handle local 100w stations well...
Now after playing with the TPA for a few days I am very happy with the results.
Audio has good depth and AGC is reponsive, also gives a nice increase in gain.
One trick to others who want to impliment this, you will need to add some code to the Adafruit library to implement the enableNoiseGate(false); function.
We need to turn the NoiseGate off or else the AGC will not ramp up with only background noise and you will not hear anything until a loud signal comes on.
Also the speaker output is NOT grounded, you need to isolate you SPK jack so that the - from the TPA2016 are direct to the speaker with no chassis grounding...
Best part in my opinion, is that ALL the AGC related settings are customisable if your want, if not, just use the voice settings from the datasheet, I have and they work great!

Stereo 2.8W Class D Audio Amplifier - I2C Control AGC - TPA2016


I will post up some code tonight... and a few pics....

73, Nick VK4PLN

Re: IRF510 amplifier failures

ekelley
 

I agree, I blew a 510 by messing with the bias adjustment. My meter was
not reading the 100 ma, so I cranked up all the way full CCW. Out of the box
it worked! My uBitX works with over 5 watts out, I'm leaving it alone. If
it works, leave the power alone and skip to fix the other problems (pop,
agc etc.) Mic that came with unit works well without amplification.
Stay QRP and look for us Sunday 7178 7278.
Ed W0OIC

On 1/30/2018 11:05 AM, Jerry Gaffke via Groups.Io wrote:
We have thousands of uBitx's and Bitx40's out there now, an occasional post to the forum about 
a blown IRF510 is inevitable

My opinion is that SWR is not what blows the IRF510's, especially when operating from 12v.
Biggest issue is that the heatsink is quite small, especially if operating continuous duty in some digital mode
and/or feeding the IRF510's more than 12v to get higher power.
Also, be aware that the gate bias adjustments are backwards (clockwise is minimum), and get very touchy
as you approach the transition region, so once the drain current starts going up it is not much of a turn 
to go from the optimal 100ma to a very hot IRF510 with 3A of drain current.
And be aware that the heatsinks as shipped are not insulated from the IRF510 tab (connected to the drain).

I'd guess most failures are due to overheating and messing up when adjusting for 100ma of drain current.
A temp sensor and foldback current limiting would avoid these troubles if you want a safety net.
Other failures due to screwdrivers in the works or flying leads touching the wrong spot and other such snafus.

Reverse DC is not a problem for the IRF510.  It has an intrinsic reverse diode from source to drain,
will blow the traces or coils between it and the power supply.  Or, with some foresight, the fuse
you put into that power supply lead.  Where you need reverse protection is going into the remainder
of the board, be it Bitx40 or uBitx.  A 1n4148 diode would suffice, a 1n400x would not get quite so hot,
but there is no problem with running all that stuff at 0.7 volts less.  

Having a full wave rectifier in line with the power supply to the IRF510's would reduce the voltage
there by 1.4 volts.  And have a significant hit on output power available.

In post 22597, KB1GMX reports:

My experience with IRF510s is extensive and much different.  I rarely kill one even during experimenting.  I use them for RF power though 6M.  How much 8 in a parallel 4x4 push-pull at 6M running 225W!  My favorite is two in a push pull amp (K500r/wa2eby design) with 28V running about 55W on 40m and 37W at 10M and after 6 years of wrong antenna and all sorts of usual havoc its still running with the same pair. 

So the IRF510 is capable of being worked very hard, and still surviving when driving a high SWR.

Testing an antenna system with no more than 12v into the IRF510 should be fairly bulletproof.
If you want to reduce power further, reduce the drive level to the final using R136 on the Bitx40, RV1 on the uBitx.
Again, note that these pots work backwards, fully clockwise is minimum drive.

Jerry, KE7ER


On Tue, Jan 30, 2018 at 04:54 am, John Brock wrote:

I have not received my uBitx yet. I’ve been  reading this forum for about two weeks. Looks like PA failures is a huge problem.

Are the two main causes reverse DC power and high SWR?

For the DC polarity problem how about a full wave rectifier at the DC input? Two diode voltage drop a problem with this approach?

What would be the best way to limit PA  power out to a very small value to allow a manual tuner to be used for the SWR issue?

 


Re: New case found

Randy
 

I believe you need at lest 6" x 6" x 2.5"

Re: New case found

Randy
 

Re: New case found

David Arthur
 

I have the 6.7" x 5.1" x 3.1" blue metal case from ebay. 

https://www.ebay.com/itm/6-7-x-5-1-x-3-1-Blue-Metal-Enclosure-Project-Case-DIY-Junction-Box-F8Z7/252898313469

It barely fits my bitx40, and I mean barely. Like 1mm or less of clearance after I cut out some plastic bits. 

Definitely will not fit the ubitx.

--
David K4DBZ
Unofficial bitx chatroom: https://discord.gg/CrHvWFc

Re: IRF510 amplifier failures

Nick VK4PP
 

Ok, So my next mods for the uBITX is to install a voltage boost for the PA.

LARGE heatsink + ALU case mount the 510, even a thermostatically controlled fan...
The boost converter can go up to 30v. I understand that the electro caps C98 and C99 will need to be upgraded too?
Any other thoughts?

Why? well becuase its fun, and I like playing... and I have a packet of 20 spare 510s... and the priceless look on the XYLs face when one does go off will be hillarious.

73, Nick, VK4PLN

Re: New case found

Paul Smith
 

They're nice cases. It was a tight fit but I used this one for my BITX20 V3B
https://www.aliexpress.com/item/90-200-165mm-Metal-metal-chassis-instrumentation-shell-with-panel-screws-enclosures/32833797285.html?spm=a2g0s.9042311.0.0.H9P2R3

Be aware that the panels are steel so they're harder to work with. I had an alu one cut to replace the front one.

Paul ZS2OE

uBITX drive level.. #ubitx

Nick VK4PP
 

HI Group.
I have been looking at upping the power, what effect does RV1 have on this?
I understand it is for adjusting the input drive level to the second pre-driver.
Can anyone elaborate a bit more on its adjustment?

73 Nick, VK4PLN

Re: uBITX drive level.. #ubitx

Nick VK4PP
 

Just thinking, Ill have to stay under 20W anyway as the T30-6 in the LPF will start to saturate any higher?
Thoughts?

73, Nick, VK4PLN

Re: uBitx audio potentiometer question.

John Backo
 

Think about it...what does a volume control actually do?
It controls the drive of the stages following it -- it has no effect on
prior stages, and really has little effect on following stages other
that regulating the drive level.

Almost all volume controls are audio taper, 100-250K units. They are
audio taper because that is the way our ears naturally respond to sound.
They are about 100K or so because that is what provides a reasonable range
to drive to the following stages.

It is not complicated in this case. Everyone who has ever used a radio
or a music player has used a volume control. It is a simple potentiometer.
If one used a higher value, then one has to turn it up a bit higher to get
the result one wants. And audio taper is used because it provides a
greater dynamic range than a linear one...but a linear pot will work.

Use what you have; if it is unsatisfactory, then use another until you get
the effect you want. It is one of the most common pots out there, available
nearly everywhere.

john
AD5YE

Re: uBITX drive level.. #ubitx

Jerry Gaffke
 

It ups the power.

Increase RV1 until received audio starts getting distorted, then back it off a little.
Alternately, if you don't have a big enough heat sink, increase RV1 until the IRF510's blow, then back it off a little.

If you turn up RV1 all the way and need a bit more, you can try increasing the gain of the microphone amp by decreasing the value of R63.
Doesn't really matter much which end of the transmitter you raise the gain, as those diode mixers and bidi amps have 
some serious dynamic range.

I have no idea where, but at some point all those 2n3904's in the driver and pre-driver will not have enough oooomph
to drive the capacitance they see in the IRF510 gates hard enough, and the amp will distort.
Allison has cautioned that not driving those gates hard enough can blow the FET's due to
the drain to gate capacitance raising the gate voltage with each RF sine wave enough to exceed Vgs-max.
Farhan has said that if you want much more than 20 watts out of the uBitx, the IRF510 final should be
on some other board.  Otherwise, I assume it will interfere with the low level stages up front.

I've been thinking that it would be interesting to build the WA2EBY amp,
see how hard the uBitx driver at Q92,93,96,97 can drive it.
Could get an idea by removing PA+12 from the IRF510's and checking to see how much RF
develops across the 100 ohm load at R97+R98.
Perhaps use something like the IRF510 final from the Bitx40 as the WA2EBY driver stage,
if you can figure out how to get it to work at 30m.


> Ill have to stay under 20W anyway as the T30-6 in the LPF will start to saturate any higher?

I can only suggest that you look hard at what WA2EBY did with his amp.
He spent months getting that thing to work correctly, and he's a lot smarter than I.

> Why? well becuase its fun, and I like playing... and I have a packet of 20 spare 510s... and the priceless look on the XYLs face when one does go off will be hillarious.

Hope your XYL has a good sense of humor.
Reminds me of scaring the crap out of my little sister when I was 12
by discharging several hundred volts from a big bank of electrolytics salvaged from old TV sets.

Jerry, KE7ER



On Tue, Jan 30, 2018 at 04:38 pm, <nickpullen@...> wrote:
I have been looking at upping the power, what effect does RV1 have on this?