Date   
ubitx pcb size

Joe Parisella <joe.parisella@...>
 

can one confirm the actual dimension of the ubitx board L by W ?

Tnx

Re: troubleshooting no TX SSB #ubitx #ubitx-help

Jerry Gaffke
 

Yes, if you can transmit CW then it has to be somewhere between Q6 and Q22,
since CW is transmittted by unbalancing the modulator immediately following Q22.
If the receiver works, then the three mixers and local oscillator are ok.
So if you still have trouble transmitting SSB, then it's Q6 or one of the bidi amps on the TX side,
and the bidi amps seldom give us trouble.

You could try unbalancing the modulator by injecting 5vdc through a series 4.7k resistor
at T7 pin 3 (and pin 5).  This is how we generated CW on the Bitx40:  
    https://github.com/amunters/bitx40/blob/master/CW-CARRIER%20wiring.png
If that does transmit CW, then it has to be around Q6.

Your 10mhz scope may just barely see something in the 12mhz IF section through Q42, 
and probably nothing at all in the 45mhz IF section at Q20,21,22.
If you wind up debugging those sections, you may need to build a diode RF probe or something similar.

Jerry


On Wed, Feb 28, 2018 at 02:50 pm, John wrote:
But as CW seemed to work the first day I thought I had to look somewhere in the modulating circuitry. Have the schematics

Re: troubleshooting no TX SSB #ubitx #ubitx-help

John
 

Don't know when I get to it.. but I will follow your lead.
I already ordered some germanium diodes to build a RF probe.

To be continued..

John

Re: ubitx pcb size

Mike Woods
 

On Thu, 1 Mar 2018 at 11:55 AM, Joe Parisella <joe.parisella@...> wrote:
can one confirm the actual dimension of the ubitx board L by W ?

Tnx

Re: U1 fried

Clark Martin
 

The TDA2822M data sheet lists an absolute maximum one amp output output current.  Since this chip is apparently prone to blowing out on short circuit I would add a .5A fast blow fuse in the speaker line, between the PCB and the headphone jack.  It doesn’t need a fuse holder, it could be soldered in (using a fuse with pigtail leads).  It would still be easier and cheaper to replace than the amp IC.

I’ll likely add this mod to my µBitx.  I don’t intend to short it out but then almost no one does.


Clark Martin
KK6ISP

On Feb 28, 2018, at 2:22 PM, John <jjczon@...> wrote:

I fried mine when I plugged in a stereo sony noise canceling headset.
So it does not only happen with mono plugs.

Hopefully the spare TDAs with sockets will arrive soon so Incan start troubleshooting my no power problem.
To be on the safe side and avoid another wait I also ordered some IRFs ;)

Re: U1 fried

Jerry Gaffke
 

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.

Jerry


On Wed, Feb 28, 2018 at 03:51 pm, Clark Martin wrote:
The TDA2822M data sheet lists an absolute maximum one amp output output current.  Since this chip is apparently prone to blowing out on short circuit I would add a .5A fast blow fuse in the speaker line, between the PCB and the headphone jack.  It doesn’t need a fuse holder, it could be soldered in (using a fuse with pigtail leads).  It would still be easier and cheaper to replace than the amp IC.
 
I’ll likely add this mod to my µBitx.  I don’t intend to short it out but then almost no one does.
 
 

Re: U1 fried

Clark Martin
 

The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.

An example of the adapter board:


And plug headers to plug them into an IC socket (or solder in).




Clark Martin
KK6ISP

On Feb 28, 2018, at 2:49 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

So where did you get your spare TDA2822M's?

The TDA2822M is $7 for two on ebay, quite expensive for what it is.
Mainline distributors like Mouser and Digikey say it's discontinued.
ST no longer makes it, sources may be drying up.

My uBitx has a part on it marked "TDA2822M" but no ST logo, not sure who makes it.

Re: U1 fried

Clark Martin
 

The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I doubt the chip would blow so fast that FB fuse wouldn’t protect it.


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.

Re: U1 fried - Replacement

Brian L. Davis
 

Re: UBitx no audio! Could use some advise

Brett Deschene
 

Ok! So I tried what was suggested and here is what I found. 
R253 was bad and  I was able to replace but that did not fix. 
I suspect a blown TDA2822M. I have one on order, so now I wait until it arrives and I swap it out.  If there are still issues I will continue to work the problem and post if I get stuck again. Thanks Jerry!

-Brett Deschene
KN4AQC 

On Feb 28, 2018, at 10:59 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Remove PA-PWR from the rig so the IRF510's won't be working, then try sending CW.
Does the sidetone come through the speaker?  If not, you have a very simple 
path from CW-TONE to the speaker to debug.  Perhaps wire a speaker between 
the junction of R250,R251 and ground, should hear the sidetone there if it's coming 
out of the Nano properly. 
 
If not, triple check connections at the volume pot and out to the speaker.


Many here have reported a blown TDA2822M, apparently due to shorting the speaker line to ground.
Probably best to add a series resistance of 4 to 8 ohms at the output of the TDA2822M and/or
reducing the supply voltage to the TDA2822M:      https://groups.io/g/BITX20/message/42723

If you suspect a blown TDA2822M, you could of course swap that chip out.
Hard to get as NXP has discontinued manufacture, perhaps now cloned in China?
An alternative is to google for "lm386 kit", and wire that into the volume control pot.
Perhaps permanently.

If you hear the sidetone when transmitting CW but no receiver audio, try soldering a wire
across nodes M1,M2 in case the relay at K2 is not working properly.  Does that fix receiver audio?

Can you hear a pop when stroking C50 with a screwdriver?

Beyond that, perhaps try the tricks shown in this video on receiver debug.
The wire he uses is just 3 or 4 feet of hookup wire, nothing on the other end,
it is acting as an antenna to pickup up random noise.
  http://bitxhacks.blogspot.com/2016/12/troubleshooting-bitx40.html


Be sure to restore the hacks I suggested (PA-PWR removed and M1,M2 short) before
trying to operate the rig.

Jerry, KE7ER




On Wed, Feb 28, 2018 at 04:20 am, Brett Deschene wrote:
Audio is completely nonexistent. No sidetone heard from CW, no static, hissing, popping, nothing.
I am pretty sure the issue is something simple and located on the board somehow but even with the schematic of the received audio path I just do not know how to diagnose and am not sure where on the board to take readings. Any help would be much appreciated.

Re: U1 fried

Jerry Gaffke
 

Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of 2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever roll the board.
Though I'm pretty sure I could solder the SMD into place with just some short wires,
not bothering with the adapter board.

> The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I doubt the chip would blow so fast that FB fuse wouldn’t protect it.

Yes, I think a 4 ohm resistor would probably do, I was getting rather cautious when I saw how hard the M part was to obtain.
I'm suspicious that with a 12v supply it is close to the edge, they seem to blow with little provocation.
Most of the datasheet seems to assume a max of 9v.
The fact that it works down to 1.8v reinforces this notion.

The fuse might protect it, depends on the failure mode.
The fuse costs about as much as the TDA2822D.

Jerry


On Wed, Feb 28, 2018 at 04:02 pm, Clark Martin wrote:
The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.
 
 

Re: Results of MAX9814 in uBitx #ubitx

John <passionfruit88@...>
 

Thanks Tim.

One additional benefit of the MAX9814 solution is the reduction in TX pops both when switching in and out of Tx mode. How much reduction is dependant on the sensitivity. At 30% input volume it's total, at 7-10% it's partial but enough in my opinion.

All the best, 73, John

Re: U1 fried

Allard PE1NWL
 

NJM2073D seems to be a replacement for TDA2822, price is about one dollar:

http://mklec.com/components/integrated-circuit/op-amps/jrc-njm2073d-stereo-audio-power-amplifier

73 Allard PE1NWL

On Thu, March 1, 2018 01:45, Jerry Gaffke via Groups.Io wrote:
Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of
2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever
roll the board.
Though I'm pretty sure I could solder the SMD into place with just some
short wires,
not bothering with the adapter board.

The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I
doubt the chip would blow so fast that FB fuse wouldn’t protect it.
Yes, I think a 4 ohm resistor would probably do, I was getting rather
cautious when I saw how hard the M part was to obtain.
I'm suspicious that with a 12v supply it is close to the edge, they seem
to blow with little provocation.
Most of the datasheet seems to assume a max of 9v.
The fact that it works down to 1.8v reinforces this notion.

The fuse might protect it, depends on the failure mode.
The fuse costs about as much as the TDA2822D.

Jerry

On Wed, Feb 28, 2018 at 04:02 pm, Clark Martin wrote:


The TDA2822D in effect replaces the “M� version.  It appears the
same
except it’s an SMD part.  You can get SMD to through hole adapter
boards
that would let you use one with the µBitX.  It would likely be cheaper
than buying the “M� version.
 
 

Re: Designing Maritime Radio #bitx40

Skip Davis
 

Hi Qonita,


This sounds like a good project, most of what you are doing will involve programming. Hardware wise you’ll need to setup the output filters as either lowpass or bandpass. All Maritime and commercial services use Upper Sideband (USB) and they are also channelized. You will need to set your mode to USB and you could setup the encoder as a rit/clarifier. If you are in need of more than one channel the encoder switch can be used to change or step through channels. Also you could program the display to readout the channel number and frequency. This would streamline your code a lot and maybe leave room for decode program for the GPS position stream and DSC functions. 

Have fun with it and let us know how it goes. 


Skip Davis, NC9O 

Re: U1 fried

K5ESS
 

Tayda has the TDA2822L for $0.29 each with 126,973 available.  It’s an 8 pin DIP.  Didn’t see any glaring differences looking at the data sheets but another pair of eyes might see something.  Also I noticed that the datasheets show power outputs with a 4 ohm load with a max Vcc of 6 volts so a 4 ohm resistor might not provide protection with a Vcc of 12 volts.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Clark Martin
Sent: Wednesday, February 28, 2018 6:03 PM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.

 

An example of the adapter board:

 

 

And plug headers to plug them into an IC socket (or solder in).

 

 

 

 

Clark Martin

KK6ISP

 

On Feb 28, 2018, at 2:49 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

 

So where did you get your spare TDA2822M's?

The TDA2822M is $7 for two on ebay, quite expensive for what it is.
Mainline distributors like Mouser and Digikey say it's discontinued.
ST no longer makes it, sources may be drying up.

My uBitx has a part on it marked "TDA2822M" but no ST logo, not sure who makes it.

 

Re: U1 fried

Michael Hagen
 

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP



On 2/28/2018 4:06 PM, Clark Martin wrote:
The chip is rated to work with a 4Ω load so a 4Ω resistor should do.  I doubt the chip would blow so fast that FB fuse wouldn’t protect it.


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.






-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Re: U1 fried

John
 

I ordered on eBay. Ordered the TDA2822L and the TDA2822M.
The L comes from the US and I paid $3.99 for 5
The M comes from China and I paid $2.75 for 10.
So at least I will have some spares.

First ordered the Ms butbthat will be a long wait. So after I saw the La in the US I ordered those as well.

John

Re: U1 fried

Jerry Gaffke
 

Now that we have a bunch of sources for the part,
I might be more inclined to experiment.

Resistance of a small incandescent bulb can go up a factor of 10 when it gets hot:  https://groups.io/g/BITX20/message/21901 
That or a fuse would be easier to replace than an 8 pin dip.


On Wed, Feb 28, 2018 at 07:10 pm, Michael Hagen wrote:

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP

 

Re: U1 fried

Michael Hagen
 

Pilot Lamp Bulbs.

Here is a chart from the past.  Guys that build tube guitar amps still buy them.

#47 was the most popular when I was a kid, #44 to get more Light.

There would be a lot of experimenting to see if they would work to protect the amp.

What impedance speaker you are using would be a big factor too.

73's

Mike, WA6ISP

 

On 2/28/2018 7:29 PM, Jerry Gaffke via Groups.Io wrote:
Now that we have a bunch of sources for the part,
I might be more inclined to experiment.

Resistance of a small incandescent bulb can go up a factor of 10 when it gets hot:  https://groups.io/g/BITX20/message/21901 
That or a fuse would be easier to replace than an 8 pin dip.


On Wed, Feb 28, 2018 at 07:10 pm, Michael Hagen wrote:

I wonder if a small light bulb. like the old standby #47 could protect a speaker short.

Maybe some type fast lo-mass fast Thermistor?   Something that has small resistance, but goes up quickly with a short.

Just thinking crazy.

Mike, WA6ISP

 


-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Re: U1 fried

Clark Martin
 


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:45 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of 2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever roll the board.
Though I'm pretty sure I could solder the SMD into place with just some short wires, 
not bothering with the adapter board.

Mouser has it for $1.19, minimum buy of 1.  The part number is listed as TDA2822D013TR.  The data sheet doesn’t show anything about the 013TR suffix so it’s likely referring to packaging variation (tube vs cut tape).

As to soldering it in directly, I do something like that.  If it fits you can place it over the pads and solder the inner two pins on each side right to the pads then tack solder fine wire to the outer two pins on each side and then to the pads on the PCB.  I use wire-wrap wire, sans insulation.