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CW keying by PC serial port problem.

 

Hi all,
?
In my uBitx v6, I am trying to do CW keying from a PC through serial port. For this I used DTR line from PC and used optocoupler to couple the CW port in radio like below:
?
?
Problem is it works for first few word sent, then TX latches up to ON continuously. I disconnected the input line from PC, then also TX remain in ON. Then I connected the O/P line only to radio and kept the I/P line disconnected, power cycle the radio and set the CW mode to enable from radio. After 30 sec or so, the TX again comes to ON automatically. This indicates problem is in the O/P circuit that connects to radio. There is noise somewhere that puts the photo-transistor in conduction mode automatically without any input. But how this is happening ?
?
Thanks
 

¿ªÔÆÌåÓý

Its picking up RF and locking.

Try adding 0.1 or 0.01 uf across the DB9 wires and also the 914s and see

Raj

On 17/11/2024 11:42 AM, VU3KFK via groups.io wrote:

Hi all,
?
In my uBitx v6, I am trying to do CW keying from a PC through serial port. For this I used DTR line from PC and used optocoupler to couple the CW port in radio like below:
?
?
Problem is it works for first few word sent, then TX latches up to ON continuously. I disconnected the input line from PC, then also TX remain in ON. Then I connected the O/P line only to radio and kept the I/P line disconnected, power cycle the radio and set the CW mode to enable from radio. After 30 sec or so, the TX again comes to ON automatically. This indicates problem is in the O/P circuit that connects to radio. There is noise somewhere that puts the photo-transistor in conduction mode automatically without any input. But how this is happening ?
?
Thanks
 

VU2ZAP has given a nice reply. Similar problems cropped up in case of a friend's FT8 interface. 0.01ufd and 0.001ufd MLCC capacitors cleared the mess.
73 de VU2UT


On Sun, Nov 17, 2024 at 12:34?PM Raj vu2zap via <rajendrakumargg=[email protected]> wrote:

Its picking up RF and locking.

Try adding 0.1 or 0.01 uf across the DB9 wires and also the 914s and see

Raj

On 17/11/2024 11:42 AM, VU3KFK via wrote:
Hi all,
?
In my uBitx v6, I am trying to do CW keying from a PC through serial port. For this I used DTR line from PC and used optocoupler to couple the CW port in radio like below:
?
?
Problem is it works for first few word sent, then TX latches up to ON continuously. I disconnected the input line from PC, then also TX remain in ON. Then I connected the O/P line only to radio and kept the I/P line disconnected, power cycle the radio and set the CW mode to enable from radio. After 30 sec or so, the TX again comes to ON automatically. This indicates problem is in the O/P circuit that connects to radio. There is noise somewhere that puts the photo-transistor in conduction mode automatically without any input. But how this is happening ?
?
Thanks



--
One of those ... ...
 

Thank you everyone for for your support. I will try the remedy and update here for outcome.
?
Regards
Ashok
 

Seems there are quite a lot of VUs using BITX! Even today evening I worked one of them on 40m SSB. Enjoying the discussion and learning a lot about BITX architecture in the process. Maybe someday?I will be able to assemble one.

73

Jon, VU2JO

On Sun, Nov 17, 2024 at 1:26?PM Sudipta Ghose VU2UT via <oneghose=[email protected]> wrote:
VU2ZAP has given a nice reply. Similar problems cropped up in case of a friend's FT8 interface. 0.01ufd and 0.001ufd MLCC capacitors cleared the mess.
73 de VU2UT

On Sun, Nov 17, 2024 at 12:34?PM Raj vu2zap via <rajendrakumargg=[email protected]> wrote:

Its picking up RF and locking.

Try adding 0.1 or 0.01 uf across the DB9 wires and also the 914s and see

Raj

On 17/11/2024 11:42 AM, VU3KFK via wrote:
Hi all,
?
In my uBitx v6, I am trying to do CW keying from a PC through serial port. For this I used DTR line from PC and used optocoupler to couple the CW port in radio like below:
?
?
Problem is it works for first few word sent, then TX latches up to ON continuously. I disconnected the input line from PC, then also TX remain in ON. Then I connected the O/P line only to radio and kept the I/P line disconnected, power cycle the radio and set the CW mode to enable from radio. After 30 sec or so, the TX again comes to ON automatically. This indicates problem is in the O/P circuit that connects to radio. There is noise somewhere that puts the photo-transistor in conduction mode automatically without any input. But how this is happening ?
?
Thanks



--
One of those ... ...
 

Two things that attracts me to ubitx. First Farhan's excellent openness with this radio, which is unmatched. If you want to learn how a communication receiver works internally then ubitx has its inside out for you to analyze, modify, hack. I know that if something goes wrong with this radio, i will be able to fix it myself, with help from community. Second, its easy accessibility means it easy to obtain, easy to build, easy to operate, easy on pocket as well. A multi-band radio so cheap and so functional is no other. I have commercial radio, but that is like a black box. You only operate the buttons, don't know what is going on inside and if it gives smoke, you are at the mercy of the manufacturer.?
?
Now coming on the issue I faced. I assembled the circuit on a breadboard with the caps as VU2ZAP mentioned and great. All works fine. Also I am doubting my PCB construction, so I will discard the PCB and make a Manhattan style board. I will update finally once all running good.
?
Thanks
Ashok VU3KFK
 

yea, the bitx is easy to repair, its low on current draw and easy to mod for USB ,Digital display if wanted and adding CW. Too bad, we need simpler kits like the bitx to occupy the low income hams who want to get on the air.
?
Some have changed the structure of the bitx and made them into dual band transceivers. Hope inkits Starts putting out new kits for them
?
73
David
ac9xh
 

i will stick with the ubitx. low cost proven, and easy to repair.Also the bitx40. As for microphones, i just open both ends, grab some paper, ohm both ends out. if the radio requires an electret mic element, i remove the dynamic element, install the other and go for broke.Most newer CB mics , even with the up/down can be wired to the radios
?
Ashhar created a miracle with the ubitx. I hope he would investigate a 6 meter all mode transceiver.Or maybe produce a matching RF Power Amplifier to directly match to the ubitx and bitx
?
?
73
David
ac9xh
 

Heard that VU2EVQ linear amplifier was? made specifically for BITX working on 40m. There are several hams in my region using it along with BITX, with good signals on 40m. Unfortunately, it is no longer in production, though VU3GEX located near?my place has homebrewed one of that design for himself and is giving a very strong and clean signal on the air.

73

Jon, VU2JO

On Mon, Nov 18, 2024 at 8:35?PM david todd via <ac9xh=[email protected]> wrote:
i will stick with the ubitx. low cost proven, and easy to repair.Also the bitx40. As for microphones, i just open both ends, grab some paper, ohm both ends out. if the radio requires an electret mic element, i remove the dynamic element, install the other and go for broke.Most newer CB mics , even with the up/down can be wired to the radios
?
Ashhar created a miracle with the ubitx. I hope he would investigate a 6 meter all mode transceiver.Or maybe produce a matching RF Power Amplifier to directly match to the ubitx and bitx
?
?
73
David
ac9xh

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