I do apologize for all of the questions I am asking today. I do have another, though. I ran a continuity check on each of the legs of the trifiliar transformer and they all test good. However, I get continuity between all of the legs. In other words, there is continuity all the way around the transformer. Is that normal?

Thanks,
Wayne

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Wayne,

I have a different radio set up with Windows 10, but I know that the OS sound settings can be very squirrelly.? Look for "Sound" app.? When you plug in your QDX you should be able to see the sound card appear and disappear when you plug in and unplug the QDX.? I would not use any external sound card since the QDX has a built-in sound card. To open the Sound app is slightly obscure.? Search "Control Panel" in the search box.? Go to "Hardware and Sound", then click on "Sound".? This should then have a list of sound devices on the computer. You should see the sound card appear in both "Playback" and "Recording".? The "Recording" side shows your receive audio and there is a bar graph on the right of the app that shows the level.? For my FDM-DUO, this level shows at about 50% to get a good level on WSJTX.? Transmit is shown under the "Playback" tab.? Under "Properties" in the lower right it opens a new pane that has "levels" if you need to adjust output.? When the radio is transmitting, you should see the bar graph under Playback and the appropriate device showing a level.?? I make my radio device "Default" for Playback and Recording, and I generally disable the other stuff, such as built-in mics and speakers, for testing purposes.? Windows is very finicky with sound configuration in my experience.?? Seeing the level on "Playback" doesn't necessarily mean the radio is putting anything out.? It just means Windows is creating a sound to send to the radio.? Personally, I would go to the Windows level setting mentioned above, and see if you can get the radio to come to life by slowly adjust the slider from nil upward.? There's no harm in leaving the radio in transmit if it's not putting anything out.

Computer audio systems were (in my humble opinion) easier to deal with on Windows XP or even Windows 3.11.? Since Windows 7, things have become much more obscure.? Not that other OS settings make it easy either.

73

Charles - NK8O

In order to make room for L508, D508 is installed with the body on the left side, with the stripe facing down, which is different than any of the other diodes.

There is a blurb in the text that discusses D508 and D511, but it doesn't mention this--you sort of have to infer it from the photograph of the board.

Hope that helps,
Jonathan KN6LFB

I had a similar (maybe lightning) problem with a QCX+5W.? ?In that case I replaced the Si 5351 A-B-G? several times as well as the QCX demodulator chip (you don't have)? without getting it going.? ?

I wondered if the first 2 5351A B GT 's? were miss sold pre-programmed ones so tried one from another source.? I used my spare CPU chip too the third time of praying and it all worked again.? I've not swapped the CPU back yet but suppose I ought to get round to it.??

?

The chip that definitely did work was?

On 24/08/2023 17:41, Wayne Greene wrote:

I ran RF filter sweeps on all of the bands to see if maybe something was wrong with my LPFs (assuming that's what this tests).

Wayne.

It tests the BPFs. Unless your LPFs are very bad they will make no noticeable difference.

73 Alan G4ZFQ

Looking at the photo on page 24 of QMX manual h, I think maybe diode D508 may be pictured in the wrong orientation.

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My main ham system is a Pi-400. Works great and no funny issues like Windows.

Thanks. I'm sure there is one, as well. I'd say this is causing me to pull my hair out, but I'm already bald...HIHI. I may try running this on a pi to see if I get better results.

Wayne

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I've been following the thread on your audio issue. Very strange as obviously the sound card is working and Windows sees it. I'm not a Windows guy, just have a test setup with Win10. Anyway I'm waiting to see what the solution is. I'm sure there is one.

Awesome. Thanks for the response. I ran RF filter sweeps on all of the bands to see if maybe something was wrong with my LPFs (assuming that's what this tests). All part of my still troubleshooting my audio problem.

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Yes, it's actually quite good for 80M. Better than mine.

Ronan,
I was the guy that posted the limiter circuit back when. Here is a link to it:
No, it does not distort until levels get quite loud. This is essentially the same as what the telephones utilized for nearly a century so nothing new.
I did publish a simple RF AGC circuit in January 2021 page 33 (since improved) but is not applicable here. Hans will eventually implement AGC in the QMX as a superior firmware feature. This is a true Software Defined Radio and the audio processing is entirely digital, making Automatic Gain Control just a software code entry. Values beyond a selected level are simply re-mapped to provide low distortion compression. Just like Flex and the other "Big Boys" do.
In the meantime, you might try an external jack (if you don't want to use a speaker) with the resistor and limiting diodes. It's cheap and effective. Try it yourself and see if it works. There will always be naysayers and detractors but I always advocate trying something just to be sure. Especially something so simple and cheap. Pennies really.
It's a hobby. Have fun!
72, Don

This is the band sweep of 80M on my QDX. I'm wondering if this is normal:

What do the RF Plots look like?

-mike/w1mt

On Thu, Aug 24, 2023 at 02:19 PM, N1EDC wrote:

I posted a couple days ago....

I saw that. Similar things were tried with the QCX and do work up to a point but they're not a proper solution. I'd rather not have to bodge the hardware when the problem can be sorted out gracefully in firmware.

I'm sure Hans will get round to it during his daily spare 12 seconds.... ?

Joking aside, this really should be a priority as there is very real potential to cause hearing damage with these sudden violent jumps in volume. Similar to KE0WVA, my day job is in music and sound production so I kinda need what's left of my hearing to stay undamaged.

Cheers,
Ronan?

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OK, thanks! I'll add that to my things to try! :-)

Couldn't imagine that those delays should be normal, but it's odd that so much else seems to work!

Paul

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On QMX, it's been suggested to put a 47v zener from drain to ground on each side of the output transformer, to protect against high SWR over voltage.

Wouldn't that also obviate the need for that commutating diode?

Paul