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UBitx v6 - no transmit power

 

Nick,

I am glad that we could help.? Have fun with the uBitx!

73
Evan
AC9TU
 

Congrats Nick!

On 11/05/2024 2:54 PM, nickredmayne via groups.io wrote:
It lives!

Reflowed, rather than replaced, R60. Restored R1 (though your comments noted). Checked resistance - now in order.
At the same time, reflowed mic cable both ends, and removed redundant speaker from mic.

Turned on, pressed PTT, red led illuminated, and needle flickered up to 7 or 8 Watts with a loud 'Yes!'

However, attaching an antenna and tuning around 40m I couldn't hear any activity... strange... and then the aurora alerts started to ping in on my phone.

Gave a shout on 20m and made QSOs up to German/Danish border.

Thanks very much for your patience and that of Raj and others, guiding me through the diagnosis. I think the resolution wasn't entirely logical- my unreasoned methodology - but the result is very satisfying.

(Now to fit an AGC circuit...)

Best,
N
 

 

It lives!

Reflowed, rather than replaced, R60. Restored R1 (though your comments noted). Checked resistance - now in order.
At the same time, reflowed mic cable both ends, and removed redundant speaker from mic.

Turned on, pressed PTT, red led illuminated, and needle flickered up to 7 or 8 Watts with a loud 'Yes!'

However, attaching an antenna and tuning around 40m I couldn't hear any activity... strange... and then the aurora alerts started to ping in on my phone.

Gave a shout on 20m and made QSOs up to German/Danish border.?

Thanks very much for your patience and that of Raj and others, guiding me through the diagnosis. I think the resolution wasn't entirely logical- my unreasoned methodology - but the result is very satisfying.?

(Now to fit an AGC circuit...)

Best,
N
 

Nick,

No problem.? Remember that R1 is not needed for normal operation; only if you want to install a battery for portable operation.

73
Evan
AC9TU
 

Thanks Evan,

I'll have a ratch in my of stuff, and failing a revelatory discovery, order new resistors.

Sorry this is such a long tale of woe.

Best,
N
 

Nick,
R1 is 10 ohms.? R60 is 4.7k ohms.

73
Evan
AC9TU
 

Was is 4.7k of 47k?
 

Also, just noticed on the board, whatever R1 was, it has disappeared...
 

Looks like it is - no reading of resistance or continuity...
 

Nick,

R60 may be open. Please check.

Raj

On 09/05/2024 5:12 PM, nickredmayne via groups.io wrote:
Thanks Raj. I've checked, and can't detect an obvious short, plugged in or out.
 

Curious about led not illuminating...
 

Thanks Raj. I've checked, and can't detect an obvious short, plugged in or out.
 

¿ªÔÆÌåÓý

Nick,

There may be a short between mic and ground. If it cheks OK unplugged then short

may be happening when it is plugged in. Check.

Raj

On 09/05/2024 4:28 PM, nickredmayne via groups.io wrote:

Q6 voltages on LSB with no modulation, 12v supply:

C- 9.27
E - 1.24
B - 1.89

I can't detect voltage on mic cartridge... and red led is not illuminating.

Best,
N
_._
 

Q6 voltages on LSB with no modulation, 12v supply:

C- 9.27
E - 1.24
B - 1.89

I can't detect voltage on mic cartridge... and red led is not illuminating.

Best,
N
 

Thanks. Will do...
 

Hi Nick,

Check the voltage on Q6.? With no modulation, it should be close to:
Collector - 10.1
Base - 2.03
Emitter - 1.4

Also, verify that there is voltage on the mic cartridge.

You do need to select one of the SSB modes for the above tests.

73
Evan
AC9TU
 

Hi Evan,
Some, lateral, progress.
I measured RF voltages from TP2 to 8, and didn't register much at all? just 0.02v on the last two with PTT pressed on CWU.
For want of anything better to do, save listening to the clicking of an impotent relay, I thought I'd stick a straight key in the key socket.?
Guess what? 10w into dummy load...
Armed with this revelation I examined the mic plug wiring, and examined it again. Then took apart the mic housing. All seems correct, but still no power on SSB when whistling, shouting into the mic.

I'm wondering whether the electret capsule is faulty - have ordered a replacement, or indeed part of the microswitch is worn out - will test fully when I have a moment.?

Apart from the above, is there anything else I should immediately examine?

I'm not there yet, but feel heartened that I at least have not made things worse.

Best,?
N
 

Hi David,

I'm heading down that avenue now. Thanks for the prompt.

Best,
N
 

Hello,

Since ur both having a NO SSB power output, have u checked the mic circuit? and make sure the ubitx is actually in the correct settings? Might check the signal flow from mic thru mic amp circuit too. might have a bad connection preventing the microphone from conveying the audio to the amp ,hence no SSB.

if you look at the v6 schematic q6 is the mic preamp. its a 2n3904. check ur mic connections and the signal flow thru q6 onward.Im betting if some of you can get the cw but not SSB, its something probably simple. if any of you wired up a different mic, check the wiring. For no trnamit at all, I Know this sounds stupid but i did it. I connected a key into the mic jack and the mic into the headphones jack, This was during a 3 am attempt ot get my new (at the time) v6 running so i could try some DX.

Needless to say ,after waking up it solved its own problem. Also might try checking ur raduino.Just a suggestion.

And if any of you are having this after changing firmware on the raduino, might check ur settings and alignment

hope this helps.

73
David
ac9xh

On Sunday, May 5, 2024 at 09:09:23 PM EDT, Divakar Rao <vu2ffw@...> wrote:


yes i understand, CW and SSB path's are different so in? effect we have SSB issue in common.

From: [email protected] <[email protected]> on behalf of nickredmayne via groups.io <nickredmayne@...>
Sent: Sunday, May 5, 2024 9:36 PM
To: [email protected] <[email protected]>
Subject: Re: [BITX20] UBitx v6 - no transmit power
?
Sorry to hear that. In fact it's not the same problem. I have no TX power in any mode.

Best, N

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