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Don,
Aside from this small RFI blip I think it's safe to say we're all so pleased with the performance of your AGC design that it was even more compelling to squash this small bug. A big THANK YOU for a wonderful contribution to our hobby!

John
KC9OJV

Terry, i will try to boot up to Mint and try it, I'll? let you know.

Joel
N6ALT

thanks Jeff, appreciate ?it.
Kn4ud ?
--
Allen ?Merrell

I spent most of the last two days experimenting. My oscillation when using that bypass capacitor was due to attaching the ground return from the pot to the audio input of the AGC board. With the bypass capacitor in place (10 nF on my test, 470 pF on Kees' board) the resistance of that return wire afforded enough of a voltage drop to create a feedback path.
If I were to encounter RFI or audio feedback I would heartily recommend a 10 nF capacitor across the audio input of the AGC. If you encounter a squeal, then open the ground return from the volume control pot right near the board and do all that is possible to make a low resistance ground for the 5 volt power return (as well as the RF).
My sincere thanks for all of the work that you folks invested and please accept my apologies for failing to anticipate the problem. 73, Don

Allen,

Nice work, looks great. I'll continue to experiment and let you know if I find anything out of the ordinary.

Jeff KC5UFS

--

I had the same problem? (kit board) - and the cap across the audio input (bevore C1) was the solution for me too.

Just to give some feedback and thank everybody for the investigation of this problem. I used a 10nF film capacitator .
AGC also seems to be working...

Sascha, DL5SMB

Len Steel,
Is your enclosure metal or plastic?
Just one more possible cause.

I ordered mine towards the end of April, there was stock showing at the time of order but this soon changed. I had several email exchanges with Sunil, over the course of my wait, with a final notification of shipping about 3 weeks ago. I chose to use IndiaPost as DHL charge extra on delivery to the UK. Shipping took 10 days. I have found the case and supplied components to be great considering what you are getting for the money. No it's not a Yaesu or Icom but if that's what you want go and spend half a grand or more. This thing is $60 delivered anywhere in the world. The power switch is a little intermittent but I can live with that until it fails and needs replacing.
Considering the popularity of these cases (overwhelming Sunil I'm sure) I'm surprised I wasn't waiting longer, remember this is cottage industry in the North of India.? ??

I just uploaded 4 files for the Nextion 3.2 display. They are for the basic and enhanced to work with Dr Ian Lee's CEC 1.094 firmware. I am starting to work on the 3.5 display next.
I would appreciate input on these files if you choose to use them. They are not an enlarged version of the 2.4 they are done on an actual 3.2 size scale.

kn4ud
--
Allen ?Merrell

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: ubitx_32E_F_0_2e.tft

Uploaded By: Allen Merrell

Description:
32B is for basic and 32E is for enhanced

You can access this file at the URL:
/g/BITX20/files/3.2%20Nextion/ubitx_32E_F_0_2e.tft

Cheers,
The Groups.io Team

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: ubitx_32E_F_0_2e.HMI

Uploaded By: Allen Merrell

Description:
32B is for basic and 32E is for enhanced

You can access this file at the URL:
/g/BITX20/files/3.2%20Nextion/ubitx_32E_F_0_2e.HMI

Cheers,
The Groups.io Team

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: ubitx_32B_F_0_2e.tft

Uploaded By: Allen Merrell

Description:
32B is for basic and 32E is for enhanced

You can access this file at the URL:
/g/BITX20/files/3.2%20Nextion/ubitx_32B_F_0_2e.tft

Cheers,
The Groups.io Team

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: ubitx_32B_F_0_2e.HMI

Uploaded By: Allen Merrell

Description:
32B is for basic and 32E is for enhanced

You can access this file at the URL:
/g/BITX20/files/3.2%20Nextion/ubitx_32B_F_0_2e.HMI

Cheers,
The Groups.io Team

I did it exactly as Mark did and I'm using Kees' PCB.

John
KC9OJV

Ian :?

I did as you suggested within the uBITX Manager :?

FWIW, I soldered the cap across the audio input pins on the underside of the board. I didn't have an SMD so it's just a plain old leaded part...I'm not even sure what technology it is (it's blue), it's what I had in my junque boxe. I listened around last night on 40M and it sounds OK, there's plenty of audio. Nothing weird on xmit, either, that I could hear.

As always, YMMV. :)

I have some 43 mix beads laying around so if have a chance I'll remove the cap and try them and see what happens.

Now I'm looking into the S meter connection but that's for another thread.

Mark AA7TA

Forgot to ask. Did you connect the capacitor across the connector end to ground of C1 or the 2N3904 Base end of C1 to ground ?

73 Kees K5BCQ

Howdy,

I am seeking someone close to Atlanta, GA that has a working Bitx-40
"Kit" the one that you just do the final wiring and put the "kit" in a enclosure.

My "kit" receives great but does not transmit.

Thanks in advance.

Hugo