Radio now does not demodulate --

[KL7KN]

The rig was working normally. Example, WWV was strong and clear, good voice audio, on 20M, heard W1AW/4 very clearly.
***
Took radio portable on a trip. On testing, the antenna showed 1.2:1 via the display.
Tried calling on SSB, no luck. Tried to send a CQ with CW and before I could complete the call, the rig malfed. Screen black. A power reset gave me a working rig.

Tried again. Malfed again. Now, when trying to RX WWV using AM mode, all I get a solid tone - I presume this to be the carrier. NO voice, no clicks etc. Using SSB mode (both U and L) still nothing but a tome. No SSB signals on 20M and no CW signals heard at all.
--Also, Zero power out, I suspect I've smoked the BS-170s. I have some on order.
***

Radio still receives, in as much as I can hear a tone from WWV. The tone will rise and fall as I tune across the WWV carrier. So - I'm calling rig as on frequency.
--Reflashed the firmware per the DL2MAN 'load your callsign' instruction.
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Callsign displayed, so I am assuming a good load. Still 'receives' (as above) but no voice, just the tone - again, I assume from the carrier at WWV, thus my 'will not demodulate'
***

Any suggestions on where to go from here would be appreciated.

//Don

[KL7KN]

With some time to do additional troubleshooting....
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While using a dummy load and the USB port for power, I get a loud signal in an external receiver when keying the rig. The frequency of the signal matches the displayed freq. So - I'm assuming the driver/MOPA part of the TX chain is fine and working. The new BS 170 will fix the rest.
****

The 'tone' heard on 10 and 15 MHZ - seems to be an internal 'birdie' for lack of another term.
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Putting my (harmonic rich) signal source to work, I still believe the rig to be "on frequency" and the external source produces the same 'tone' product as noted above. However - this is the source feeding directly into the (tr)uSDX ant input. IOW - quite deaf apparently for antenna fed signals.
Caveat - when the external antenna (a dipole cut for 40M) is connected, the background noise does increase markedly. I take this as signals - and noise - making into the RX chain.
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I have studied the 'new' drawings for the rig. The MCU has an output labeled as "PB1 audio" and the earphone jack is fed by a line with the same label. From this, I am ass-uming the MCU is operational as I have robust audio out.
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The Tayloe Detector is feeding into the MCU via the PC0_ADC0/PC1_ADC1 lines. I don't see a link to damage the devices here via either high SWR, RF feedback (common mode) or a voltage drop on the +5 VDC line - without several other devices also being damaged and that damage being noted as no display, no audio, etc.
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The 3Vdc line feeds the 5351 (clock) chip which, in turn, feeds the Tayloe Detector.
It looks like I need to tear into the rig and check the 3VDC voltage line. I doubt this is an issue as the varying tone would seem to indicate the Tayloe Detector is working at some level.

So - what says the hive mind on checking the 3VDC source - and seeing if the Tayloe Detector or the 5351 being hosed?

73
Don

[dl6sez]

Hello OM,

i would replace Q1 RX mute Transistor, maybe it has a problem to work with conducting only partly at RX,
wouldn't be easy to measure because it could also be a capacitive coupling to any connection in it.
If this doesn't help check the LT6231 look with an oscilloscope what it is doing...
Good luck and hope you find it fast

73 de Chris

[KL7KN]

Thanks for the reply, Chris.

All I need is an O'scope to do just that.

I'm limited to a DMM and a separate RX, dummy load etc. My days of having real test equipment are long gone. Hence my idea of checking voltages....
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I have spent quite some time pondering the (in)famous Q1. I doubt that Q1 is the base issue as the rig with transition normally TX/RX under USB power into a dummy load. Muting is as before this trouble started. I hear background noise from the antenna....so, while the rig may be deaf in some ways, it isn't totally gone.
****

I'm scratching my head over the tone found at 10 and 15 MHz with no antenna attached. It shows up on just these frequencies..... Given the nature of the quadrature detector, I'm puzzled over these very strong 'birdies.
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Having reloaded the software with no effect, I will likely try loading the newest Beta version and see what develops. At this stage, my lack of 'real' test equipment has me in a bind...
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Once again, Chris - thanks for reading and making a comment.

[dl6sez]

Hello Don,

but i don't believe something is wrong at LT6231 because you can hear birdies and it changes if connected to an antenna. So just try to change Q1 it could be half alive, simplest thing to change and cheap. You see the simple circuit, it is txing right, so the path of RF must be okay with all components (T1 T2 LPF....).
Birdies are normal we have two oscillators working in (tr)uSDX, okay they are higher in qrg but i also have many many birdies at lower frequencies than the oscillators have.
Maybe you can borrow a simple oscilloscope from another Ham?

73 de Chris

[KL7KN]

Once again - my thanks.

Living where there are zero electronics parts stores (Alaska) means buying via mail order and a week to a month delay. "Simple and cheap' are location-based terms, eh?
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As an aside -
I uploaded the Beta software with no problem (Thanks to DL2MAN!) and to my surprise, on 20M heard a K6 calling CQ.
The obnoxiously loud birdies are still there and WWV on 10 & 15 Mhz is just the same loud tone. The 20M band was also full of loud tones, tho I did hear a warble of one of the digimodes.
Odd, to say the least,
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Now somewhat confused, I reloaded the current stable software (3b) and the same issues are heard - tones etc.

I re-reloaded the Beta software and now nothing but tones. The AVRDUDESS app indicated a good upload, but the rig now seems to have the same problem set...no matter the software load.
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Given the time/effort to obtain the infamous Q1 - would just bypassing the device (jumper) cause any (additional) damage?

Also - when Q1 was working, why were the tones (birdies) not heard before this current adventure? Confusing.
***

I spent many years of my life working on radios, none this software driven to be sure - just the same, so my thought processes may be different.

Thanks again for you r time in this matter!

73
Don

[KL7KN]

After once more loading the (new) Beta software with a modified callsign - and on a dummy load... Load appears to be good.

F/W shows 2.00u

When activating the 'spectrum scope" I see random spikes running across the display, and when tuning a 'birdie, it (the birdie) doesn't show on the scope as a spike (?).

On an antenna: Nothing. I was trying to repeat the other day where I heard couple of SSB/CW signals.

Listening on a 'calibrated' RX, the (tr)uSDX leakage shows the rig to be on frequency, or near enough for me to be satisfied for now.

I guess I'll be ordering a Q1 (2N7002) and see if swapping it helps. This goes against a lifetime of fighting against 'swap to fix' troubleshooting but lacking an O'scope - I'm left little choice.

Thanks for reading.

[KL7KN]

(sigh) If it isn't one thing, it's another.

I looked online for a (tr)uSDX parts breakdown...no luck.

So - what size of 2N7002 device fits the board?

SOT023, SOT 363, SOT 363-6, the list goes on.

Any clue you can throw my way would be greatly appriciated..... Because, at least in this case, size does matter.

Thanks in advance!

[s57l]

https://dl2man.de/wp-content/uploads/20 ... m_1.0.html

[KL7KN]

https://dl2man.de/wp-content/uploads/20 ... m_1.0.html

Many thanks!!!!


73
Don

[KL7MJ]

Living where there are zero electronics parts stores (Alaska) means buying via mail order and a week to a month delay.

What happened to Frigid North? I miss a lot of things about Alaska, but Frigid North is high on the list!

73,
Mike, KL7MJ/4

[LILO]

Hi!

Did you manage to fix it?