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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

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?

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?

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

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)