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Understanding ground isolation #ubitx #teensy #filters

Rob French (KC4UPR)
 

Hey there,

I'm looking to try making a DSP audio filter, for both transmit (e.g. compression) and receive (narrow, wide, notch filters) using a Teensy 3.2 and Teensy Audio Board.  My plan for the receive audio is to put it inline in my uBITX v5 between the audio preamp and the volume control (i.e. before the volume control), and use a pair of 1:1 isolation transformers on the input/output to connect it to the preamp (input) and volume pot (output) respectively.

I would like to run the Teensy as both a standalone DSP filter in the uBITX, but also as the interface to the computer (i.e. as a combined USB audio/serial device).

My plan is to power the Teensy off the 5V from the Raduino, and also connect it to the Raduino via serial (D0/D1 pins on the Raduino) so that (a) I can pass thru CAT commands from the computer to the Raduino via the Teensy when applicable, and (b) control filter parameters from the Raduino when operating standalone.

My question is, what exactly needs to be isolated?  I understand I need ground isolation between the Teensy audio I/O and the uBITX audio I/O, so I plan on 3 isolation transformers.  But how does this really isolate the ground?  If I'm running the Teensy off the Raduino 5V, there's a ground connection there presumably, and from what I can tell, all of the grounds on the Teensy Audio Adaptor are unified (except for the VGND for the headphones, which I'm not using).  So I feel like all of the grounds are connected, and I'm not really sure what the isolation transformers are buying me.

Do I need to use a separate regulator for the Teensy? (Although that would still have a ground connection to the uBITX ground, so...)

I freely admit I don't know a lot here.

Regards,
-Rob


Re: CEC firmware upgrade issues...

MVS Sarma
 

did you select 1602 in ubitx.h  at line 30 or so and deselect  nextion at line 35 or so, and save , before compiling?

all the best
sarma  vu3zmv


On Fri, Sep 6, 2019 at 6:14 AM Steven <wera106@...> wrote:
Thanks for the suggestions. I uploaded the CECFW 1.2 for my V5 board using the arduino IDE this evening. I had to choose the ATmega328P (old Bootloader), to upload - choosing ATmega328P resulted in an error and no upload. The result? Everything seemed to upload fine. But now my screen has 16 black rectangles on the top row, and nothing else, not even static..... Hmmmm.... I must be getting close. Any more suggestions for tomorrow night's session with the uBitX?


Re: CEC firmware upgrade issues...

Steven
 

WOO HOO!!! Happiness, joy, and smiles have rained down upon my shack. I figured out that I needed to change the version to 5, and the display from nextion to 1602 in the ubitx.h file.  I heard several 40 meter ssb voice and a strong cw sig on 7.114. That felt good. Now I have the weekend to play with and learn from this radio.Thanks all.
Steven KM4WIP


Re: CEC firmware upgrade issues...

Steven
 

Thanks for the suggestions. I uploaded the CECFW 1.2 for my V5 board using the arduino IDE this evening. I had to choose the ATmega328P (old Bootloader), to upload - choosing ATmega328P resulted in an error and no upload. The result? Everything seemed to upload fine. But now my screen has 16 black rectangles on the top row, and nothing else, not even static..... Hmmmm.... I must be getting close. Any more suggestions for tomorrow night's session with the uBitX?


Re: New wiring diagram version

Jerry Gaffke
 

Looks good to me, I like seeing a separate relatively small fuse for the main board.
Anything goes wrong there, it is much more likely to blow the fuse before blowing something on the board.

Though as I suggested earlier, there are dozens of ways to do this right.
And even more strongly held opinions on how one should do it.

Jerry


On Thu, Sep 5, 2019 at 02:27 PM, Adrien F4IJA wrote:
This setup gives me the possibility to choose on S2 weither to use an external PSU or not for PA PWR (if I'm a my QRA I'll have a PSU available, when on a hill only the battery).
I all cases, the battery is legacy to supply the uBitx and the uBitx is powered on by S1. Maybe it could be a good idea to have a 2 separate ways S1 to cut off both battery and PSU line).

Also, the D1 is in serie as proposed.

What do you think ?


Re: max PA PWR voltage ?

Murray Wills (ZL2IQ)
 

Hi. I am running mine on 13.8v with no problems.

Murray ZL2IQ.


From: BITX20@groups.io <BITX20@groups.io> on behalf of Tom, wb6b via Groups.Io <wb6b@...>
Sent: Friday, September 6, 2019 9:29:42 AM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] max PA PWR voltage ?
 

Hi,

Here is a thread where the person powered the whole uBitx from 15 volts and raised the output power substantially. 

This was an earlier revision, so should re-evaluate if any components on the new uBitx revision would be bothered by 15 volts. One older version of the uBitx, for example, had issues with the audio amp IC rupturing and expelling smoke above 12 volts. But that was due to a batch of flakey ICs.

Raising the voltage to the whole uBitx seemed to have some advantage by improving the gain through the intermediate RF stages driving the finals. 

https://groups.io/g/BITX20/message/57370

Tom, wb6b


Re: High pitched tone at 14.074 mhz

John (vk2eta)
 

On Thu, Sep 5, 2019 at 07:25 AM, Chris [N7CCX] wrote:
"touching the crystals on the raduino or on the board dont change anything"
Hello Chris,

Do you mean both crystals on the Raduino proper and on the Nano's board?

For comparison I do have birdies (mine is a V3) here and there as I have on my FT-817, albeit not as significant as on the uBitx. On the uBitx on 20m band I have two noticeable ones at around 14,006 and 14,179 and an S6 one at 13,996.

Birdies should shift frequency significantly when switching from USB to LSB as the 2nd LO swings from around 57Mhz to around 33Mhz thereby changing the harmonics beating frequencies that can occur on the board.

Other sources of impact on noises could be power supply (switch mode) and location of wires inside the box. Not likely as you mentioned you disconnected the antenna from the board itself.

73, John (VK2ETA)


Re: max PA PWR voltage ?

Tom, wb6b
 


Hi,

Here is a thread where the person powered the whole uBitx from 15 volts and raised the output power substantially. 

This was an earlier revision, so should re-evaluate if any components on the new uBitx revision would be bothered by 15 volts. One older version of the uBitx, for example, had issues with the audio amp IC rupturing and expelling smoke above 12 volts. But that was due to a batch of flakey ICs.

Raising the voltage to the whole uBitx seemed to have some advantage by improving the gain through the intermediate RF stages driving the finals. 

https://groups.io/g/BITX20/message/57370

Tom, wb6b


Re: New wiring diagram version

Adrien F4IJA <adrien.grelet@...>
 

Hi Jerry,

I've thinked a lot about your post and here is a diagram of the setup I want to make on my rig :


This setup gives me the possibility to choose on S2 weither to use an external PSU or not for PA PWR (if I'm a my QRA I'll have a PSU available, when on a hill only the battery).
I all cases, the battery is legacy to supply the uBitx and the uBitx is powered on by S1. Maybe it could be a good idea to have a 2 separate ways S1 to cut off both battery and PSU line).

Also, the D1 is in serie as proposed.

What do you think ?

--
73's
Adrien F4IJA
https://www.qrz.com/db/F4IJA


Re: Antuino manual

iz oos
 

Rechargeable AA batteries are nominally around 1.2-1.25v, 6 of them would provide 7.2-7.5vdc. Would it be too low?


Il 05/set/2019 19:02, "Garry48" <ggkraemer@...> ha scritto:

Chris,

here is the Antuino group forum on :

https://groups.io/g/Antuino/

Garry

On 9/4/2019 7:20 PM, Christopher J. Shaker, KJ7BLE wrote:

Guess we need an #antuino hashtag.

Thank you for the answer that it does NOT charge the batteries.

Does anyone have the specs for the power input?

Thank you,
Chris Shaker
KJ7BLE


On 9/4/2019 7:18 PM, Mark - N7EKU wrote:
Hi Christopher,

The schematic shows that the ground connection for the battery pack comes from the power input jack and this becomes disconnected when a plug is inserted there.  So there is no circuit anymore for getting power to the battery pack and it will not be charging or anything.

73,


Mark.


Re: Project : Ubitx go box with batteries (topic will be updated upon works done)

Adrien F4IJA <adrien.grelet@...>
 

I'm actually working on the PCB to add the AGC mod and also a Smeter for my uBitx.

I've choosen the VK2ETA AGC mod and the KD8CEC Smeter.

Here is my schematic made with Kicad and the board which will be 85x40mm :


You can find details on my wiki here http://www.tobeca.fr/f4ija/doku.php?id=ubitx:agcsmeter
--
73's
Adrien F4IJA
https://www.qrz.com/db/F4IJA


T/R Relay sticking!

chuckr@hostu.org
 

Hi all, whats your thoughts, while using wsjt-x for ft8 I have been noticing a peroid of not receive data on the water fall, until I click the tune button on and off. Then all works as it should. Noticed that when it is sticking (?) the sound of the relay un keying is real faint or quieter than normal. I beleive this is pointing to at sticky relay. This is a un moded V5 board and has been working flawlessy for several months of FT8 untill lately.  Is there any know quick/easy fix (often not worth it in the long term) or just replace it with the same brand and model number or one of the brand names that has been used for the low pass relay replacements ( something start with ax I think. So whats your thoughts, recomendations or other help or support,,, and many thanks for all on this group.
73
chuck


Re: High pitched tone at 14.074 mhz

Chris [N7CCX]
 

No.. gonna try moving the radio.. it is a bit high noise in the spot it is in.. on my 450d it would be s5-s7


Re: High pitched tone at 14.074 mhz

Adrian Chadd
 

It sounds like an internal spur. Do you have the same thing on any other radios in that room?


-a


On Thu, 5 Sep 2019 at 11:48, Chris [N7CCX] <chriscoel@...> wrote:
I should add its there through all volumes, and is same with or without nextion firmware.

relative to the earphones its not loud but noticable...

Am I over thinking?


Re: High pitched tone at 14.074 mhz

Chris [N7CCX]
 

I should add its there through all volumes, and is same with or without nextion firmware.

relative to the earphones its not loud but noticable...

Am I over thinking?


Re: Antuino manual

Christopher J. Shaker, KJ7BLE
 

Ashhar:

Thank you for designing the Antuino for us!

Chris Shaker

On 9/5/2019 1:57 AM, Ashhar Farhan wrote:
A 12v power supply is recommended. It draws about 80 ma of current when in operation. Most of it goes to light up the display. I didn't have any spare pin on the Arduino to turn the power to the display on/off, so it remains on, otherwise, we could have done with less than 40 ma of current.
I have operated it on 9v battery too. However, for most, I operate it with the six AA cells inside the case, I haven't run out of the first set yet.
- f

- f

On Thu, Sep 5, 2019 at 1:20 PM Christopher J. Shaker, KJ7BLE <cjshaker@...> wrote:

Raj:

Thank you. I did actually resolder both sides, and used a solder sucker to remove the excess.

I'll look at it again tommorow.

It powered up and worked with a 12 vdc power supply.

Chris Shaker
KJ7BLE

On 9/4/2019 11:35 PM, Raj vu2zap wrote:
Chris,

The power connecter leads have to be resoldered on BOTH sides of the PCB. The reason
is that PTH has been drilled out wile fitting the socket.

Raj


At 05-09-19, you wrote:

I appear to be having the same problem with my Antuino.

It won't power up with the battery pack. I reflowed the solder joints. The diode appears to be operating like a Capacitor, ie - it conducts power for a short period of time, then stops conducting power.

What are the power specs for the external power input? Does the Antuino charge NiMh batteries when connected to external power? I looked on the schematic, and it does not appear to say, either.

Thank you,
Chris Shaker
KJ7BLE


Re: Antuino manual

Garry48
 

Chris,

here is the Antuino group forum on :

https://groups.io/g/Antuino/

Garry

On 9/4/2019 7:20 PM, Christopher J. Shaker, KJ7BLE wrote:

Guess we need an #antuino hashtag.

Thank you for the answer that it does NOT charge the batteries.

Does anyone have the specs for the power input?

Thank you,
Chris Shaker
KJ7BLE


On 9/4/2019 7:18 PM, Mark - N7EKU wrote:
Hi Christopher,

The schematic shows that the ground connection for the battery pack comes from the power input jack and this becomes disconnected when a plug is inserted there.  So there is no circuit anymore for getting power to the battery pack and it will not be charging or anything.

73,


Mark.


Re: Builder for Disabled

Curt
 

Another point of view is to stay with the standard LCD as it works decently. The color displays add appreciable power consumption. Someone with motor skill issues may do better with the standard unit, but you do have to press the tuning knob then use the knob to select the menu action. A v5 board may not need mods for spurious. I added a simple agc mod, the one by vk3ye, it squashes big signals as I tune across a band.

73 Curt


Re: Antuino manual

Jerry Gaffke
 

The Antuino draws 0.080ma at 5v.
With a linear regulator to 5v, the regulator is dissipating (12v-5v)*0.080 = 0.560 Watts.
Much over 12v going in and the LM78L05 will soon overheat and go into thermal shutdown.

See the datasheet for the Theta-JC and Theta-JA  (junction to case if case has a good heatsink,
junction to ambient air if just air cooling).  Those specs give the temperature rise of the silicon junction
for a given dissipation in Watts.
 
Jerry


On Thu, Sep 5, 2019 at 07:05 AM, Garry48 wrote:

 

 

https://n2htt.radio/2019/05/26/hello-antuino/

This gent says 9-12VDC, but the voltage regulator data sheet says it will take up to 30VDC.  Take note of the milliAmp rating.  It is low, so I'd stay at 12V or less.  No sense converting voltage into heat.

There is a group on groups.io; when I find it, I'll post it.

Garry / WD0DUD


High pitched tone at 14.074 mhz

Chris [N7CCX]
 

Hi everyone, I am experiencing something odd, when tuning around on dummy load or no antenna/dummy load attached i hear a high pitched squeal that goes up in frequency as you tune a couple khz up (like to 14.079) then drops off.

If you set ATT to anything even like 8.. it goes away.

I am on a ubitx 4, with the KD8CEC Firmware and nextion display, unplugging display completely does not fix it, touching the crystals on the raduino or on the board dont change anything.. pulling out the antenna from board does not remove it.

it seems this is a birdie, could it be a bad arduino?

It is semi noticable on a tuned antenna but very very very faint under the noise.. This only happens on the 20m FT8 frequency and then somewhere in the high 5 mhz range (dont care about the 5mhz).

Sound clip -- lots of static cause its faint into my PC recording, may need to turn it up, and it will get louder partially in.
https://drive.google.com/file/d/1ie7Dxx6_ecvsOrBjYVQ1iFXLDf3om7DH/view?usp=sharing

thanks for the help, everything else works great on this, other than the steady constant tone/"beep"

Chris
N7CCX