Re: Something to look out for: possible cause of PA failure (QDX etc).
I have yet to start my builds (I bought one of everything), but I've been reading the posts here for a while and slowly getting prepared.? I have even bought a pack of BS170s in anticipation of possibly needing them - hopefully I don't!? I've also grabbed various inexpensive heat sinks made for rasp pi, etc, considering a possible modification to the bolt on steel washer design.
Tisha and Paul, if you have any links or pics of implementation of M2.5 copper screws/nuts, copper crush gaskets, or other heat dissipation ideas, I'd appreciate it.? A cool radio is a happy radio!
Peace,
Todd K4MSW
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Hans,
Best wishes on getting well soon. ?Glad you have the support of your XYL. ?It¡¯s amazing you¡¯re able to accomplish all you do, and still have time for self and family.
Take care!
Todd K4MSW
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Roy,
I strongly advise you try to figure out root cause before you replace the bad transistor.
?At a minimum, disable the power source to the PA by lifting a leg of L502, or removing it completely.?
Now you can measure gate drive voltages while not risking another transistor failure. Make certain IC503 has not failed.
JZ
On Thu, Apr 4, 2024, 11:01?AM Roy - KI0ER < ki0er@...> wrote: On my "hot" BS-170, the Drain and Gate show a direct internal short.
So the question is, if I just replace that one, am I good, or more likely, I need to find the root cause of why it went bad ... unless it's just that I over tightened the heat sink assembly?
Thank you so much John and Ludwig for jumping in to help this novice EE (I'm a retired software engineer actually)!
--
73
de Roy - KI0ER
Littleton, Colorado USA
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After months of operating as a WSPR beacon my QDX failed.
Q7, the reverse polarity protection, has gone open. The assembly
manual tells me that it has been been replaced by a more robust
component starting at Rev 4. What are my replacement options for a Rev 3.2
board?
Ron VE8RT
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Ron VE8RT <ve8rt@...>
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On my "hot" BS-170, the Drain and Gate show a direct internal short.
So the question is, if I just replace that one, am I good, or more likely, I need to find the root cause of why it went bad ... unless it's just that I over tightened the heat sink assembly?
Thank you so much John and Ludwig for jumping in to help this novice EE (I'm a retired software engineer actually)!
--
73
de Roy - KI0ER
Littleton, Colorado USA
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On Thu, Apr 4, 2024 at 08:21 AM, John Z wrote:
Is IC503 warming? during RX as well?
Hi John. No, IC503 remains cold after power up (and RX only). ? -- 73 de Roy - KI0ER Littleton, Colorado USA
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Re: [QMX] Keying CW via CAT
Get yourself a MORTTY
https://hamprojects.info/mortty/
--
73 Jim K1IR
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Roy, Is IC503 warming? during RX as well?
JZ
Ludwig,
A good step towards figuring this out is to observe or measure the gate signals at each bank of BS170s. If it is not what is expected, we can begin to peel down the possibilities at that point.
JZ
On Thu, Apr 4, 2024, 10:02?AM < DH8WN@...> wrote: John,
ok, If the current is flowing from 5 V trough the PA transistor, the current on 5 V could be around 200 mA and the heat power 1 W or so. This is much more than 60 mW and will clearly heat up the PA. It would be good to know the Duty cycle for 5 V (Terminal Diagnostics).
If the fault current is flowing via the 5 V some of the outputs of IC503 have to be ON. So IC503 could be faulty in this case. But I guess, not the whole IC503 is faulty because the PA is working partially.
An other possibility would be if the signal "TX" to IC503 is not LOW and so one pair of BS170 is ON the whole time. It depends also on the signal "CLK2" to IC501 and IC502. Are there pulses in RX mode?
Not so easy to predict the faulty part.
73, Ludwig
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Re: [QMX] Keying CW via CAT
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Ludwig,
A good step towards figuring this out is to observe or measure the gate signals at each bank of BS170s. If it is not what is expected, we can begin to peel down the possibilities at that point.
JZ
On Thu, Apr 4, 2024, 10:02?AM < DH8WN@...> wrote: John,
ok, If the current is flowing from 5 V trough the PA transistor, the current on 5 V could be around 200 mA and the heat power 1 W or so. This is much more than 60 mW and will clearly heat up the PA. It would be good to know the Duty cycle for 5 V (Terminal Diagnostics).
If the fault current is flowing via the 5 V some of the outputs of IC503 have to be ON. So IC503 could be faulty in this case. But I guess, not the whole IC503 is faulty because the PA is working partially.
An other possibility would be if the signal "TX" to IC503 is not LOW and so one pair of BS170 is ON the whole time. It depends also on the signal "CLK2" to IC501 and IC502. Are there pulses in RX mode?
Not so easy to predict the faulty part.
73, Ludwig
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With display removed, I powered up my QMX and watched the PA transistors with an infrared camera. One of them lit up in the camera within seconds of power up. It was the top-left PA transistor that began warming up. I'll remove it to see if it's bad, shorted internally or something.
I'll do other tests later this morning.
--
73
de Roy - KI0ER
Littleton, Colorado USA
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Re: [QMX] Keying CW via CAT
Hi Gary,?
Did you ever try CWTerm with a QCX??
If it's not using CAT commands then I don't understand how it is working.?
73, Mike KK7ER?
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Re: Rather not a successful build - QMX is deaf and mute
#HighBand
#qmx
This feels to me like the same issue I had with my December V2 PCB kit, where IC402 had become damaged during my testing, as I did not yet have the diode protection fix installed - but I would have figured a V3 would have that installed.? Still, I think the troubleshooting steps involving IC402 may be relevant - that you may have a receiver side problem.
73? JRJ? W9IYN
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John,
ok, If the current is flowing from 5 V trough the PA transistor, the current on 5 V could be around 200 mA and the heat power 1 W or so. This is much more than 60 mW and will clearly heat up the PA. It would be good to know the Duty cycle for 5 V (Terminal Diagnostics).
If the fault current is flowing via the 5 V some of the outputs of IC503 have to be ON. So IC503 could be faulty in this case. But I guess, not the whole IC503 is faulty because the PA is working partially.
An other possibility would be if the signal "TX" to IC503 is not LOW and so one pair of BS170 is ON the whole time. It depends also on the signal "CLK2" to IC501 and IC502. Are there pulses in RX mode?
Not so easy to predict the faulty part.
73, Ludwig
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Re: [QMX] Keying CW via CAT
Mike,
There is no CAT command in any radio for sending CW, dit by dash. You can use the RTS/DTR to do that over the serial link on many radios. There is only one CAT command for sending text (26 char max) to the radio where the radio generates the Morse.
Gary
W9TD
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Re: [QMX] Keying CW via CAT
Check out the k3ng winkeyer. You can make one with an arduino of any kind or even a STM32. Works very well here. You can buy a mini winkeyer that is only a small, featureless box with usb in, key in, paddle in and key out.
Gary
W9TD
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Hans, give top priority to taking care of yourself, family and staff.
Best wishes from Texas.
Charles K5KXJ?
On Thursday, April 4, 2024 at 08:31:55 AM CDT, Hans Summers <hans.summers@...> wrote:
Hi all
Again - please bear with me patiently...
We're just getting out of what has been a very severe 'flu experience or maybe Cv19 variant, who knows. Even after making 3 babies, none of which arrived without "complications", I've never seen my XYL bedbound for a whole week. And I've never felt as ill myself,as during the last week, either. Weakened the mental powers as much as the body. Nasty virus, very!?
XYL appears to have mostly recovered. She got home yesterday evening with the kids, finding me laid out on the sofa in exactly the same position she'd left me 5 hours earlier, and not having made it at all to the office all day even for a moment. She told me they'd been at my son's best friend's house. And that his Father had had it too. She said he's a workaholic just like you (he runs a law firm in Mu?la city) and even HE spent 5 days in bed. (I disputed the offensive "workaholic" nomenclature). But anyway, she said, he went for some medication dispensed by IV drip and now he feels a lot better. And then she said, "tomorrow I'll take YOU for an IV drip!". I said "whoooooaaaaaa! I'm actually planning on feeling a lot better tomorrow already!"
Hence here I am today, feeling a lot better... But please bear with me as 2 weeks' email and helpdesk ticket backlog is non-trivial to catch up on...
73 Hans G0UPL
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Re: Jeff Moore QMX repair--5stars!!!
#qmx
Jeff is the star quality "Elmer" that goes beyond the old-timey Elmer who just steered you in the right direction. He actually hand's on DOES what it takes! All we shaky, vision-challenged old guys have a problem actually seeing SMD parts besides actually soldering them back on the board!
Hats off to Jeff!
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73
Karl
KI4ZUQ
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Speedy recovery and good health Hans to you and family.?
---------------------------------
73 de Marek SP9TKW
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Chris / W2BPL
cube1us
Gary W9TD
Karl
Marek SP9TKW