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#ubitx-help #ubitx-help

R S
 

Opinions of help needed badly here.  About the 5th or 6th time I have turn it on, I was listening to Tom E3TH (I know the call is wrong.  All I could get) the entire 40 meter band has these sounds.  Even if volume all the way down.  I have attached an audio file.  Hope it works.  I did not try any other bands.  I can touch the finals and reduce the loudness dramatically, but still audible.  Can touch anywhere and reduce it.  Antenna and final PA are the most affecting.  The heat sink I put on the Raduino board is warm with only receiving.  I have also attached a few pictures internal.  I have a 1.5 swr on 7.277 MHz using my MFJ269C Pro.
Using a Turner +2 now amplified.  Nothing done from day one without antenna connected.

Thanks,
Ron  KJ4FFG

Mike Woods
 

Nice build Ron!

I suspect you have noise from the display getting into your audio.  This may be an earth loop issue, or it may be leaking directly in to your speaker as it is shown in the photo located alongside the display. Those of us with BITx40s will recognise that sound!  It is not normally a problem on the uBITx.

Caps (0.1uF and perhaps a 45uF) each side of  the Raduino regulator may help ... it works on the BITx40 for many.  Others may have better ideas about potential solutions. At my place the noise from the antenna is more than enough to drown out this racket, so never was an issue until the antenna was unplugged.   If it was me I would pull those curled up unused wires on your audio and Raduino jacks as these can also generate hash.  Push on the little window on the reverse side of the jack with a flat-bladed screwdriver to release the pin.   They can easily be reinserted later if you store them in the junk box, when you need them to do something.

73 Mike ZL1AXG



On 19/03/18 12:16 PM, R S via Groups.Io wrote:
Opinions of help needed badly here.  About the 5th or 6th time I have turn it on, I was listening to Tom E3TH (I know the call is wrong.  All I could get) the entire 40 meter band has these sounds.  Even if volume all the way down.  I have attached an audio file.  Hope it works.  I did not try any other bands.  I can touch the finals and reduce the loudness dramatically, but still audible.  Can touch anywhere and reduce it.  Antenna and final PA are the most affecting.  The heat sink I put on the Raduino board is warm with only receiving.  I have also attached a few pictures internal.  I have a 1.5 swr on 7.277 MHz using my MFJ269C Pro.
Using a Turner +2 now amplified.  Nothing done from day one without antenna connected.

Thanks,
Ron  KJ4FFG


--
Mike Woods
mhwoods@...

Tom VE3THR
 

Nice job on the layout Ron. Like Mike said, try some 0.1uF caps on the 5V raduino regulator. I didn't see the 4.7K pull up resistor on pins 2&3 of the raduino either. Try another spkr direct to board - no jacks and no grd on the black wire. Same noise with mic disc'd? keep power and signal/audio wires separate - not bundled. Move spkr away from display? Try running off a 12 v battery - pure DC. I had to add a 1000uF electrolytic cap across the DC power on my BITX40 to null the "clicks". Volume control wired correctly?
Good luck and let us know how you make out. Thanks for the audio clip!
73 Tom VE3THR

Brian L. Davis
 

I see that you have enclosed wiring in a tubing, did you twist the wires before sliding into the tubing.
It seems that if you don't twist the wires or replace with shielded wiring there is a lot of digital interference that can be picked up by the circuitry.
I twisted the wiring tightly and then wire tied the lines in place, I get a little tick on tuning but with any signal it is not a problem.

Tim Gorman
 

Ron,

Unsolder your speaker leads, twist them tightly together and resolder
them to the speaker. See if that helps.

Try a .01pf capacitor between the solder lugs on the speaker. See if
that helps.

As someone else suggested, unsolder your speaker leads, pull them out
from under the display, and then connect them to a speaker outside the
case and see if that helps.

tim ab0wr

On Sun, 18 Mar 2018 16:16:28 -0700
"R S via Groups.Io" <rons8=yahoo.com@groups.io> wrote:

Opinions of help needed badly here.  About the 5th or 6th time I have
turn it on, I was listening to Tom E3TH (I know the call is wrong.
All I could get) the entire 40 meter band has these sounds.  Even if
volume all the way down.  I have attached an audio file.  Hope it
works.  I did not try any other bands.  I can touch the finals and
reduce the loudness dramatically, but still audible.  Can touch
anywhere and reduce it.  Antenna and final PA are the most
affecting.  The heat sink I put on the Raduino board is warm with
only receiving.  I have also attached a few pictures internal.  I
have a 1.5 swr on 7.277 MHz using my MFJ269C Pro. Using a Turner +2
now amplified.  Nothing done from day one without antenna connected.

Thanks,
Ron  KJ4FFG

David S
 

Ron

I agree with all the previous comments about your wiring, it does need sorting.

Looking at your photographs I think your speaker impedance is 4 ohm, the one I have looks the same type but is unbranded.  A 4 ohm is too low for the TDA2822 on 12v, on audio peaks it's going to exceed the output capability of the chip.   I've changed C77 to 22uF and fitted a 47R load, using that point as an audio feed for both a digital interface and one of the cheap TDA2030 modules from China that are on Ebay.  That completely changed the audio on my 1st batch board with an FCI TAD2822.

Although I don't think that's the cause, in your recording it's sounds like "motorboating", that's a type of low frequency oscillating usually due to instability in the power to the audio amplifier.  When the received audio starts, it suddenly pops up and is very clear despite the oscillation.  If that's your normal background noise level I think your quick lucky, mines terrible, comes with living in a built up area.

Regards

David  G8DJM