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Author Topic: HELP: I am building an Pixie 2  (Read 676 times)

Offline sm5mek

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HELP: I am building an Pixie 2
« on: March 26, 2015, 09:57:01 UTC »
And i have a strange motorboat sound from the receiver,  LF is LM386, anyone having tips to filtering this?  :-\
Best regards, 72 de SM5MEK, Jenny.

Offline PG4I

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Re: HELP. I am building an Pixie 2
« Reply #1 on: April 01, 2015, 06:50:11 UTC »
Hi Jenny,

make sure your power supply decoupling is okay. Where the supply is connected to the LM386 add a 100uF electrolytic capacitor in parallel with 100nF ceramic. Connect them as close to the LM386 as possible. Also, make sure your grounding leads are as short as possible.
Joop - PG4I/QRP

Offline WH7TT

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Re: HELP. I am building an Pixie 2
« Reply #2 on: April 01, 2015, 17:17:06 UTC »
Trying using a battery as well to see if the sound is still there. That will tell you if it is the Power Supply or something else.
Edward
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Offline sm5mek

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Re: HELP. I am building an Pixie 2
« Reply #3 on: April 08, 2015, 07:35:31 UTC »
Trying using a battery as well to see if the sound is still there. That will tell you if it is the Power Supply or something else.
Edward
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Well i shifted the battery and the putt putt was dissapearing. NICE. Before that i also found a tiny tiny shortcut :-) but the motorboat was still rhere, could be that the shortcut was taking so much current so the IC didnt get enough current. Now weak hissing like a lazy cat. More tests in future.
Best regards, 72 de SM5MEK, Jenny.

Offline n7eku

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Re: HELP. I am building an Pixie 2
« Reply #4 on: April 26, 2015, 23:52:25 UTC »
Hi Jenny,

My first post here :-)

Almost every design I see using the lm386 forgets that pin 7 should be bypassed to ground.  Any small value electrolytic should be fine (5-20uF) and helps a lot.

Have fun with your pixie!

73,


Mark/n7eku

Offline sm5mek

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Re: HELP. I am building an Pixie 2
« Reply #5 on: April 28, 2015, 07:36:42 UTC »
I now got the motorboat away and heard my own signals very loud (hi) it was several problems, bad and cold solder as one, putting some component to correct point also good to do.  ??? >:(  so now have a check about the shift between tx and rx, a buisness about values to the capacitor and trimmer at the x-tal. :-\ ^-^
Best regards, 72 de SM5MEK, Jenny.

Offline AK0B

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Re: HELP: I am building an Pixie 2
« Reply #6 on: October 04, 2015, 03:04:01 UTC »
low battery voltage will also make the audio sound like its bubbling
stan ak0b