f1mqj

Mike (and others), the 7805 output is (only) 4.79V, with input at 12.55V (see picture) (Pb battery), I assume the low voltage is due to high current/power drain (0.23A = not far 2W), I don't think the low voltage could be the origin of the high consumption (the Atmega328 is given for 1.8-5.5V, downgrading clock with low voltage, but 4.79V is normal to +-5%)
I've also found Atmega328 temp is climbing very Hot (not as the 7805 but too hot for this kind of circuit), that might be the original problem, is it a defective nano board ? (despite this it start to work fine)
73 - Remi

Michael Hagen

Remi,

What do you read on the input pin of the 7805?

Still sounds "fishy"  ??  7805 does .23A OK?  Should be no problems if not hot?

Yes climbing temp is a problem?

Mike

On 6/23/2018 6:28 PM, f1mqj wrote:
Mike (and others), the 7805 output is (only) 4.79V, with input at 12.55V (see picture) (Pb battery), I assume the low voltage is due to high current/power drain (0.23A = not far 2W), I don't think the low voltage could be the origin of the high consumption (the Atmega328 is given for 1.8-5.5V, downgrading clock with low voltage, but 4.79V is normal to +-5%)
I've also found Atmega328 temp is climbing very Hot (not as the 7805 but too hot for this kind of circuit), that might be the original problem, is it a defective nano board ? (despite this it start to work fine)
73 - Remi

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10917 Bryant Street
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f1mqj

7805 Input is direct battery=12.55V (if it’s going  hot, IT me and IT HAS power to dissipate due to current x deltaV)
0,23A is a problem when :
- it’s going to heat too  Much  the 7805
- at least 2 om measured the third on their board
- it’s going to sink battery
- the processor is also heating too much
73

Jerry Gaffke

Sounds like a defective Nano.  But could still be a shorted Nano IO pin.
Might check all of those IO pins with an ohmmeter to ground, +3.3v, and +5.5v with power off,
and look again (I know you already did) for a possible short somewhere.

Maybe a bit of solder or a metal filing fell into the works?
Wash it all with alcohol (which dries fast), see if that helps?

But I think you are on the right track.
The Nano is only \$3, but difficult to remove.
If you do wind up removing it, consider installing a socket when putting the new Nano in place.
This worked well:  https://groups.io/g/BITX20/message/49986

Here's a datasheet for the CH340:  https://cdn.sparkfun.com/datasheets/Dev/Arduino/Other/CH340DS1.PDF
And a schematic for the Nano:
Jerry, KE7ER

On Sat, Jun 23, 2018 at 06:28 pm, f1mqj wrote:
I've also found Atmega328 temp is climbing very Hot (not as the 7805 but too hot for this kind of circuit), that might be the original problem, is it a defective nano board ?

Re: I need a V3 or V4 uBitx board.

Jerry Gaffke

Cool!
It does pay to just dive in and try.  Sometimes.

I am curious though, what was wrong with the receiver?
Perhaps trouble around C50?

Jerry

On Sat, Jun 23, 2018 at 05:12 pm, Joel Caulkins wrote:
I want to thank you all who held my hand through this, I am now back up and running. The low power was because I had my power supply in current limiting mode, I now have full power out and worked a field day station a 1000 miles away. I will install a fuse in the primary radio path now that I've learned a important lesson. Some people just need to learn the hard way:-)

Re: I need a V3 or V4 uBitx board.

The receiver would not work until I changed the relay. I was wondering about that myself, why would the absence of TX voltage cause the receiver not to work unless a RX voltage was missing also. I checked all that I saw on the schematic and they were all there. Don’t know.

Joel
N6ALT

Re: I need a V3 or V4 uBitx board.

Joel,

If the TX track is burnt there it is likely that a plated through hole (PTH) has also burnt.
Check along the burnt line from top to bottom connections.

Check the RX/TX supply voltages everywhere.. you could have welded the relay contacts !!

Raj

At 24/06/2018, you wrote:
Oh, one more thing Jerry, The mods I had done was the cutting of the traces per the instructions on Don ND6T's site. I bridged them back to factory and checked with a MM to make sure the path was back. There is no visible damage to the top side of the PCB as looked at with my USB Microscope, (a good one).

Joel
N6ALT

Re: I need a V3 or V4 uBitx board.

Check the PTH as I mentioned..

At 24/06/2018, you wrote:
Well after testing some voltages on the board, the RX rail is present everywhere it's supposed to be but the TX rail is missing everywhere. I'm thinking I may have toasted K1 but still checking.

Joel
N6ALT

Re: I need a V3 or V4 uBitx board.

Jerry Gaffke

If K1 welded up inside such that there was no path from pin 12 to pin 14 when the coil was not energized,
then the receiver would not get RF from the antenna and be deaf.

K3 does most of the antenna T/R switching, during receive it passes signals from the antenna over to K1.
During receive, K1 is not energized and pins 12 and 14 are connected, sending RF up into the 30mhz LPF at L1,2,3,4

During transmit, there will be some capacitve coupling between K3 pin 12 and K3 pin 14 even though those contacts are open.
So during transmit, K1 shorts pin 12 to ground to avoid feedback from antenna back into Q90 creating an oscillator.

Jerry

On Sat, Jun 23, 2018 at 07:48 pm, Joel Caulkins wrote:
The receiver would not work until I changed the relay. I was wondering about that myself, why would the absence of TX voltage cause the receiver not to work unless a RX voltage was missing also. I checked all that I saw on the schematic and they were all there. Don’t know.

Re: I need a V3 or V4 uBitx board.

MVS Sarma

It could also be possible that the transistor might be short, permanently operating the said relay.

Regards
MVS Sarma

On Sun, Jun 24, 2018 at 10:14 AM, Jerry Gaffke via Groups.Io wrote:
If K1 welded up inside such that there was no path from pin 12 to pin 14 when the coil was not energized,
then the receiver would not get RF from the antenna and be deaf.

K3 does most of the antenna T/R switching, during receive it passes signals from the antenna over to K1.
During receive, K1 is not energized and pins 12 and 14 are connected, sending RF up into the 30mhz LPF at L1,2,3,4

During transmit, there will be some capacitve coupling between K3 pin 12 and K3 pin 14 even though those contacts are open.
So during transmit, K1 shorts pin 12 to ground to avoid feedback from antenna back into Q90 creating an oscillator.

Jerry

On Sat, Jun 23, 2018 at 07:48 pm, Joel Caulkins wrote:
The receiver would not work until I changed the relay. I was wondering about that myself, why would the absence of TX voltage cause the receiver not to work unless a RX voltage was missing also. I checked all that I saw on the schematic and they were all there. Don’t know.

Re: Bitx AGC circuit

Willy,
Long time. Guess who I just Worked! W1LY 2A RI on 20m cw as K8GC my clubs call. Nice to hear ya on the band's.
73
Enjoy FD
David
N8DAH
From: BITX20@groups.io <BITX20@groups.io> on behalf of Willy <W1LY@...>
Sent: Tuesday, November 7, 2017 7:03:28 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Bitx AGC circuit

I am using this circuit without the 10K between the diode and the 2N7000 which was not in Farhan's original schematic.
It works fairly well for me.
I have seen a number versions which have not worked. One has the 10 K at "audio in" replaced with a 100K and the 100 R at the anode of the 1N4148 shown as 100K
73 Willy  W1LY

On Tue, Nov 7, 2017 at 2:31 PM, Philip Thompson wrote:
Thanks guys...all understood..

It's just that I built one for my Bitx and it doesn't seem to work.
The voltage on the gate of the fet is going up and down in response to the audio level
but there seems to be little or no attenuation to the stronger signals....
Double checked and I made no mistakes..
Phil  G4JVF

--
David

N8DAH
Kit-Projects.com

Re: I need a V3 or V4 uBitx board.

Glenn

I had similar problem some time ago. No Tx.  I could hear K1 pulling in but in actual fact it wasn't making contact. I replaced it with a different brand of relay and no problems since. But it does make me suspicious of the other relays in the uBITX. If they don't work then  a LPF may not be actually switching either.
glenn

On Sat,

Jun 23, 2018 at 04:55 pm, Joel Caulkins wrote:

Yay! K1 was indeed bad, I now have a working receiver and transmitter, however the output power is only 500mw compared to the 12 watts before. Do we think the IRF510's are shot? What would be the best way to check them or should I just replace them, I have plenty in stock.

Joel
N6ALT

Re: I need a V3 or V4 uBitx board.

Glen,

The filter relays come in and out when PTT is pressed. Saves a bit of current if you are using on battery.
I just cut a track and wired the filter relays to operate during rx and stay there.

If anyone is interested I post this mod.

Raj

At 24/06/2018, you wrote:
I had similar problem some time ago. No Tx.  I could hear K1 pulling in but in actual fact it wasn't making contact. I replaced it with a different brand of relay and no problems since. But it does make me suspicious of the other relays in the uBITX. If they don't work then  a LPF may not be actually switching either.
glenn

On Sat,

Jun 23, 2018 at 04:55 pm, Joel Caulkins wrote:
Yay! K1 was indeed bad, I now have a working receiver and transmitter, however the output power is only 500mw compared to the 12 watts before. Do we think the IRF510's are shot? What would be the best way to check them or should I just replace them, I have plenty in stock.

Joel
N6ALT

f1mqj

Thanks for advice and links (i already looked at this ch340 datasheet but it's very short and incomplete -no data about 3v3 output voltage interval)
I've got something : only 36ohms between gnd and 5V, more than 1Kohm on a spare nano, no output data shorted to gnd or 5V
BUT only 6ohms between REF and gnd (about 3K on my spare nano) And REF pin is shown unlinked on Raduino board ->
- bad nano PCB with no space between gnd and ref
- short circuit on capacitor on the REF pin
but all that hard to check and correct without unsolder :-(
first easy thing that i can do easily is cut pcb between Atmega pin 21 and REF output of the board (but i will need later to replace the capa on the other side to enforce noise reduction on analog read)
second thing is to cut and remove this unused pin between nano and raduino (in case the short circuit is on the raduino solder part)
i will keep you informed
73 - Remi

Re: #bitx40

Hi,

Any suggestions or ready code to make bit 40 VFO to encoder please ...

On Mon, Jun 18, 2018, 12:41 AM <victor.rodrigo.jimenez@...> wrote:
Hello. How are you?
Mr. I need the program of the mini arduino of my bitx40. since the one that I had was burned and I had to change it. your help is appreciated

Re: #bitx40

MVS Sarma

Try to see the link below and related previous history on that subject. you would get what you needed.

Regards
MVS Sarma

On Sun, Jun 24, 2018 at 2:42 PM, Pradeep Kumar wrote:
Hi,

Any suggestions or ready code to make bit 40 VFO to encoder please ...

On Mon, Jun 18, 2018, 12:41 AM <victor.rodrigo.jimenez@gmail.com> wrote:
Hello. How are you?
Mr. I need the program of the mini arduino of my bitx40. since the one that I had was burned and I had to change it. your help is appreciated

FS- Unbuilt uBITX & Case

W8RMV

I have a late uBITX V3 (socketed) that I received 4 weeks ago & a Sunil Case for sale.  \$150 for the pair shipped.
The uBITX comes with the Click & AGC Kees kit.  Both are brand new & unmolested.
Any questions/interest, please email me off group at W8RMV@....

Re: Heat sink

VE7CWS WRSeiler <waltrseiler@...>

Thanks fellows!

I have performed the subject install and everything seems to work just fine.

Cheers and 73

Walt VE7CWS

Ubitx schematic

Art Olson

Has anyone marked up the schematic showing rec and transmit paths via color. I recall seeing a bitx one last year

73
art N2AJO

Re: I need a V3 or V4 uBitx board.

Raj,

When the trace burned it also burned only the TX side contacts on K1 which didn’t alow RF to get to the receiver. Replacing K1 solved all problems, everything is working good now. Fortunately I keep a stock of those relays for my homebrew Transceivers.

Joel
N6ALT