Date   
Re: uB Shipped!!

Michael Baker
 

I got payment confirmation on January 4 and still waiting for my second one to be shipped.

Re: Results of MAX9814 in uBitx #ubitx

Tim Gorman
 

John,

Good job!

tim ab0wr

On Tue, 27 Feb 2018 20:42:11 -0800
"John" <passionfruit88@...> wrote:

After trying a few schemes I have settled on a MAX9814 circuit for
the AGC.

I used the Adafruit board but there are a few variations on eBay with
some probably requiring less hacking than the Adafruit design. I had
to solder a wire on a SMD component to access the CT (time constant
capacitor) pin of the MAX IC, and remove the Electret capsule.

I have attached the schematic and a few pictures of the AGC circuit
as I now have in the rig. The 5VDC is taken from the Raduino board.  

Performance wise I took two sets of measures, one with the AGC turned
down low and one with the AGC turned one third of the way up.

A few notes on the tests. I used an A/B comparison with an FT-817,
with the pre-amp off, receiving  a carrier at 1,500Hz  from local
radio stations (with attenuation). The FT-817 S-Meter seem
notoriously non-constant in the steps between the S-units, but that
is all the reference I have where I am. The AGC voltage is taken from
the CT pin of the MAX9814.

The AGC voltage fluctuates quite a lot, so I tried to record the
average value.

At high signal strength, to determine if the saturation was coming
from the AGC circuit or the uBitx upstream, I would bypass the AGC
and keep the volume down to prevent the audio circuit past the volume
pot from saturating. If the harmonics of the audio disappeared, the
AGC alone was producing distortion, otherwise it appeared at least
before the AGC, and possibly in as well.

Here are the results:

1. "Medium" AGC: input pot turned to about 30% of full scale.

FT817         AGC
S-Meter     voltage(mV)       Notes
S0                  0               
S1               300
S2               350
S3               400
S4               460
S5               510
S6               650
S7               750
S8             1,700         Large variation. FT-817 S-meter S8
plateau issue? S9            2,200          Some saturation of AGC
noted (starts to appear in audio FFT, not noticeable) S9+10
 2,460           Saturation of AGC audible, but not unplesant. S9+20
   2,460           Audible saturation of both uBitx and AGC (harsh
sound).

The AGC kicks in early and keeps the volume pretty constant until
saturation occurs. Saturation of AGC does limits the dynamic range of
receiver.

1. "Low" AGC: input pot turned to about 7-10% of full scale.

FT817          AGC
S-Meter      voltage (mV)       Notes
S0 -S4               0                                
S5                50-200            (100mv avg)
S6                  200
S7                  360
S8                  500
S9                1,260
S9+10         1,800
S9+20         2,300                 Saturation of both uBitx and AGC
(visible in audio FFT, but not really audible) S9+30         2,400
             Audible saturation of uBitx and mostly of AGC.

This is the most "FT-817 AGC" like, from my perspective, and is what
I have settled for.  I want to use the AGC voltage as an s-meter
input and this setting does produce a gap at the bottom end, but this
is not critical IMO.

In both cases I noted some small "clicks" when the AGC kicked in on
strong sudden signals. 

The maximum gain of the MAX9814 as set in the schematic attached is
of 50dB and requires screened cables in the audio circuit. I
originally had the input and output of the circuit fed to a two core
"stereo" screened cable and I would get feedback. I had to use two
single screened audio cables.

73, John (VK2ETA)

Re: UBitx no audio! Could use some advise

Jerry Gaffke
 

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: uB Shipped!!

Vince Vielhaber
 

What was your order date?

Lovely, DHL's tracking is down.

Vince.

On 02/28/2018 10:47 AM, Michael Baker wrote:
I got payment confirmation on January 4 and still waiting for my second
one to be shipped.

Re: Another shipping Notification Update

Vince Vielhaber
 

Check paypal in case you just didn't get the notice.

Vince.

On 02/28/2018 08:13 AM, Daniel Conklin wrote:
I ordered mine on the 29th of December 2017, and I haven't gotten notice
of shipping yet.
Dan W2DLC

ubitx standoffs #parts

R S
 

This Group is mighty nice.  I have enjoyed it tremendously for a while now and have learned from others here.  I have a question now.  I have installed my xbitx in an old junked Repeater Case, no testing yet, but I would like to have better choices with the standoffs for the board and display.  The display is a little too far in for my total liking.  Maybe you can see with pics.  Not finished yet.  What are the threads per inch (maybe 4-40) and so on?  I ordered some from Mouser but were surely not what I wanted and expected.  Any help is surely and greatly appreciated.

Ron
KJ4FFG

Re: uB Shipped!!

Vince Vielhaber
 

Will do! Stop by 3930 some afternoon. We rag chew from about 2pm till the net starts at 5. Looks like I'll be running the net on Tuesdays.

Vince.

On 02/28/2018 10:14 AM, Karl Schwab via Groups.Io wrote:
Hurray Vince! Let me know when you get it on the air, and I'll listen
for you! Karl, KO8S


On Tuesday, February 27, 2018 10:35 AM, Vince Vielhaber
<vev@...> wrote:



Ok, for all those waiting... I just got a ship notice that my uB has
shipped (today 2/27) and will be here on thursday (3/1). I ordered on
12/28.

Vince.
--
Michigan VHF Corp. http://www.nobucks.net/ <http://www.nobucks.net/>
http://www.CDupe.com/ <http://www.cdupe.com/>
http://www.metalworkingfun.com
<http://www.metalworkingfun.com/>





Re: Designing Maritime Radio #bitx40

Jerry Gaffke
 


There's a band-pass filter at L1, L2, L3, it is used during both transmit and receive.
You require a fairly broad passband,  but I suspect it will work fine across your 500khz.
As designed, it has input and output impedances of 50 ohms (though it likely sees a load of around 200 ohms at Q1).
I suggest you either simulate that filter in LTSpice or find some other software to model such filters,
and find new values for the inductors and capacitors such that it has a passband from 8.222 to 8.746 mhz.
Or you could just make all the capacitors smaller until you bring it to your operating frequency.
For initial testing (not when transmitting into an antenna) you could probably just short across this entire filter
with a wire, but you will now be receiving an image frequency and the transmitter may have extra outputs
at unexpected frequencies..

The low pass filter at L6, L7  allows through our 7.2mhz signal from the transmitter and blocks all harmonics
(at 14.4 mhz, 21.6 mhz, etc).  Again, would be best to obtain correct values for your operating frequency,
though simply decreasing the value of the the capacitors will probably be sufficient.
If this is not done correctly, you may wind up transmitting at frequencies other than what you intended.
This low pass filter is only used when transmitting, not when receiving.

Crystal filter should be fine, leave it at 12mhz.  
If that is not clear, then you need to read up about superhetrodyne receivers before proceeding with
your hacks to the Bitx40, perhaps in one of the excellent amateur radio publications such as
the ARRL Handbook, RSGB Handbook,  or Experimental Methods in RF Design.
There is likely something similar available in most other major languages.

Up to date firmware for the Bitx40 can be found here:
    https://github.com/amunters/
either "bitx40" (simpler hardware mods)  or "bitx40-raduino-v2" (allows the bfo to be varied)
Adjusting the tuning range in that software should be a matter of changing a few numbers,
folks in this forum could probably help if you get stumped by this.
You will also need to download the Arduino IDE to a host computer, use that to load
your new firmware into the Nano processor embedded in the Bitx40.

Should be a fun and educational project!
Hope that helps.

Jerry, KE7ER


On Wed, Feb 28, 2018 at 07:42 am, <qonita.salimah@...> wrote:

There is no requirement for the modulation itself, I think SSB is good enough and suitable for my project. Did one RF-Front End circuit work for both transmit and receive system?

What about the Crystal Filter Circuit, should I make change on the circuit? Did the Crystal Circuit aim is for keeping the IF Frequency fixed tuning in 12 MHz? 

uB Shipped!!

Lee Dziekan
 

Dec 27 ordered
Feb 24 PayPal Shipping Alert
Feb 27 DHL delivery.... signature required

Board number 084-3

Lee
N8LJ

Re: ubitx standoffs #parts

Arvo W0VRA
 

The threads are M3 × 0.5.  The standoffs I have are 11 mm long with a 6 mm male threaded part.  Lots of kits on ebay.

Re: BITX40 carrier and low output

w2vu@...
 

Hi Allard,
No, I had not tried that yet. I didn't connect this problem with a possible alignment issue. I will do that (hopefully this weekend and hopefully with help from my more technically-adept friend who was listening to me) and see if it helps.
Vy tnx & 73,
Rich

Re: BITX40 carrier and low output

Clark Martin
 


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:23 AM, Allard PE1NWL <pe1nwl@...> wrote:

Have you already aligned the PA BIAS and PA DRIVE according to the instructions on hfsignals.com?

The instructions at <http://www.hfsignals.com/index.php/ubitx-tuneup/> make no mention of PA DRIVE.  In fact this is the first time I’ve seen any indication of how to adjust PA DRIVE.


  1. Attach a dummy load to the antenna
  2. Insert a ammeter (you may use your VOM meter in high amps range) into the PA power supply’s positive line
  3. Keep the PA BIAS preset (RV1) to fully clockwise position. Now when you press the PTT button, the ammeter should read about zero.
  4. Increase PA BIAS without speaking into the mic until the PA current shows 100 ma
  5. Give a loud and long HAAAALLLOOWW into the mic and the current should jump to slightly over 1 amp
  6. Adjust the RV136 to increase the PA drive if the current doesn’t jump all the way to 1A
  7. Keep monitoring your signal on a nearby receiver.

Re: Better Schematic

Walter
 

On Wed, Feb 28, 2018 at 07:23 am, Jerry Gaffke wrote:
The uBitx surface mount R's and C's are all in the 1206 package.
The surface mount 2n3904's are are mmbt3904's.
The audio amp is the TDA2822M variant (M says it's in the 8 pin DIP package).


On Wed, Feb 28, 2018 at 05:54 am, Walter wrote:
What value SMD's do you think these are? I see 0603,0805, 1206. 
Outstanding.  I have them ordered thanks for the help
 
--
73, W9KJO
Walter

Re: Speaker Jack

Bob Bennett
 

I would also like to have a headphone jack and an internal speaker. How do I wire this?

Bob

Re: Speaker Jack

Walter
 

On Wed, Feb 28, 2018 at 07:01 am, Richie Chambless wrote:
Hello Walter,

I have been doing some work around this same subject. You can take the low-level audio signal to an external amplifier by connecting the signal in to Vol-H (R170). This is the yellow wire coming off of the audio connector (diagram on HF Signals is incorrect). You can also reduce the headphone volume by inserting two small value resistors (under 100 ohm) in series with the output of the audio amp. Do this by connecting the output of the amp to pins 4&5 of the headphone jack. Now put the resistors across pins 1&2. I hope that makes sense! Google the Realistic DX-160 schematic to see what I’m talking about.
Are you talking about something like this?

Would the Yellow wire signal act kind of like a line out at a constant level?  Does it need a cap to isolate the line from the device plugged into that line? I think it may not be true line level but a constant output level.  The signal link has a control to manage the level.

I am not an EE but still trying to learn and figure out a good way to get this done.

Thanks
 
--
73, W9KJO
Walter

Re: ubitx standoffs #parts

Michael Hagen
 

They are metric 3 mm.  So you have to use 3mm bolts those for the supplied spacers.

Most places have plastic spacers too.  Get 4-40 size ones.  Un-threaded 0.096" or 0.1" and you can use #4 sheet metal screws or self thread 4-40 screws.  Check Mouser.  Or mail order surplus, like All Electronics.

Buy long ones and cut them off to the length you need.   The ACE and other local hardware stores have brass and Al. tubing for model making.

K&M Metals or some name like that.  Al. , Brass, or Copper is easier to work with than steel.

You could cut up spacer from them too.  Could even go to putting nuts at the other end?

Our local ACE has a whole section of hardware, including Metric.


73's Mike WA6ISP



On 2/28/2018 8:20 AM, R S via Groups.Io wrote:
This Group is mighty nice.  I have enjoyed it tremendously for a while now and have learned from others here.  I have a question now.  I have installed my xbitx in an old junked Repeater Case, no testing yet, but I would like to have better choices with the standoffs for the board and display.  The display is a little too far in for my total liking.  Maybe you can see with pics.  Not finished yet.  What are the threads per inch (maybe 4-40) and so on?  I ordered some from Mouser but were surely not what I wanted and expected.  Any help is surely and greatly appreciated.

Ron
KJ4FFG

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

Re: U1 fried

K5ESS
 

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Walter
Sent: Wednesday, February 28, 2018 6:16 AM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

On Wed, Feb 28, 2018 at 04:08 am, DrZ wrote:

Last night while trying various speakers, smoke started rolling out of my uBitx.  The audio IC U1 was fried.  I'm assuming the audio line shorted while inserting plugs.  They are cheap (5 for $6) and I'll install a socket for easy replacement.  But a word of warning.....
Howard K4LXY

i Noticed the volume switch has an on/off switch built into it.  perhaps I will connect this in line with the speaker jack and turn it off before plugging and unpluggings speakers and stuff.
 
--
73, W9KJO
Walter

Re: Designing Maritime Radio #bitx40

Chris Brewer
 

Hi Qonita,

You're quite welcome, and Jerry covered your question very nicely in his reply. 😀

SSB is preferable for voice communications anyway: it's more efficient than AM (amplitude modulation) and uses less bandwidth to transmit the same information. I only mention it because radio services typically have regulations specifying the allowed modulation methods. If you're working on a theoretical project then this doesn't matter.

Good luck with your project!

Regards,
Chris Brewer, AC9GN


On Wed, Feb 28, 2018 at 10:31 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

There's a band-pass filter at L1, L2, L3, it is used during both transmit and receive.
You require a fairly broad passband,  but I suspect it will work fine across your 500khz.
As designed, it has input and output impedances of 50 ohms (though it likely sees a load of around 200 ohms at Q1).
I suggest you either simulate that filter in LTSpice or find some other software to model such filters,
and find new values for the inductors and capacitors such that it has a passband from 8.222 to 8.746 mhz.
Or you could just make all the capacitors smaller until you bring it to your operating frequency.
For initial testing (not when transmitting into an antenna) you could probably just short across this entire filter
with a wire, but you will now be receiving an image frequency and the transmitter may have extra outputs
at unexpected frequencies..

The low pass filter at L6, L7  allows through our 7.2mhz signal from the transmitter and blocks all harmonics
(at 14.4 mhz, 21.6 mhz, etc).  Again, would be best to obtain correct values for your operating frequency,
though simply decreasing the value of the the capacitors will probably be sufficient.
If this is not done correctly, you may wind up transmitting at frequencies other than what you intended.
This low pass filter is only used when transmitting, not when receiving.

Crystal filter should be fine, leave it at 12mhz.  
If that is not clear, then you need to read up about superhetrodyne receivers before proceeding with
your hacks to the Bitx40, perhaps in one of the excellent amateur radio publications such as
the ARRL Handbook, RSGB Handbook,  or Experimental Methods in RF Design.
There is likely something similar available in most other major languages.

Up to date firmware for the Bitx40 can be found here:
    https://github.com/amunters/
either "bitx40" (simpler hardware mods)  or "bitx40-raduino-v2" (allows the bfo to be varied)
Adjusting the tuning range in that software should be a matter of changing a few numbers,
folks in this forum could probably help if you get stumped by this.
You will also need to download the Arduino IDE to a host computer, use that to load
your new firmware into the Nano processor embedded in the Bitx40.

Should be a fun and educational project!
Hope that helps.

Jerry, KE7ER

On Wed, Feb 28, 2018 at 07:42 am, <qonita.salimah@...> wrote:

There is no requirement for the modulation itself, I think SSB is good enough and suitable for my project. Did one RF-Front End circuit work for both transmit and receive system?

What about the Crystal Filter Circuit, should I make change on the circuit? Did the Crystal Circuit aim is for keeping the IF Frequency fixed tuning in 12 MHz? 


Re: U1 fried

Jerry Gaffke
 

I assume the mono to serial adapter would just short the mono signal to both stereo signals.
So you are back where you started, plugging a mono jack into that adapter will kill the TDA2822M.
Could work if you avoid this, but not foolproof.  And thus not suitable if I'm anywhere in the vicinity.

Might be better to add a series resistor inside the radio, and/or reduce the supply voltage to the TDA2822M

Jerry, KE7ER


On Wed, Feb 28, 2018 at 09:22 am, K5ESS wrote:

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

 

Re: Speaker Jack

Richie Chambless
 

Yes, the yellow wire is the full signal from the product detector. Check your volume potentiometer to ensure it’s connected to the end (orange should be on middle lug). I would think your external amplifier has a capacitor input on it, so I don’t think another cap is necessary. Check to see if DC is present across the volume pot when the side tone is activated.