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On a roll with getting T507 actually connected to the radio, getting fw .017 loaded into radio and all by myself getting into PuttY repeatedly and seeing positive results!?

Then I see here someone putting in "the dreaded diode mod" and wondering what mod!?

There on QRPLabs.com site are TWO mods! The diode mod MAY SOLVE LOW POWER OUT PROBLEMS! Fancy that! "Birdies" on receive, unwanted oscillations...you mean those tones up and down the band like someone tuning up on CW and left his tool box sitting on the key ?? I got em! And I don't hear them on the IC-7300 nor the RS-918 mcHF clone.

Will report the results...
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73
Karl
KI4ZUQ

Hello Karl,

The purpose of the diode mod is solely to protect the IC402 (MUX chip) from some unwanted parasitic ringing which may occur on some bands while transmitting (QMX in TX mode). While in RX mode, the diode has no effect, being reverse-biased. As far as I can tell, It won't eliminate any birdies, nor will it alleviate any low-power output issues.

The tones that you describe, that go up and down the band, I can hear them as well, on both the QMX and IC7300 - they're not caused by the kit. However, the fixed, very narrow birdies may be caused by the SMPS modules. Hans knows about them and will fix that in some future firmware update.

Regards,
YO3GFH
op. Adrian

On 20/03/2024 16:22, Karl via groups.io wrote:

"Birdies" on receive,

Someday this will be fixed in firmware..

These "birdies" were with or without antenna and I see that the diode fix has nothing to do with birdies! Unwanted oscillations destroying stuff seemed pretty important since the text directed the mod before powering up! Heck, this one was powered up last year!

I had heard the term birdies before but actually had no idea what they were. I always blew it off as someone tuning up! Now I know a teensy bit more. The receive on this QMX seems quite good just to the ear. I have three other SDR based receivers to compare and the all seem about the same and equal to the QMX.

At any rate, that diode is going in tonight/ tomorrow! Thanks all!
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73
Karl
KI4ZUQ

Here is my diode^
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73
Karl
KI4ZUQ

Should have left well enough alone. It is not the diode because I removed it. I suspect I "cooked" that Q whatever underneath the add-on. Now, receive not anywhere what ir was and there is a screech (bigger than a birdie) just below 14.300 mhz...

Any suggestions?

Same to you, fella! Suggestions on how to fix! Har, har!?
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73
Karl
KI4ZUQ

Panic before thinking. Q508 fine or receiver would not work and it does. Birds or birdies? on digital USB, not detected on CW.

Ordered lifetime supply of SMD SOG323 1N4148 diodes from Amazon. I will send a cut of 4 or 5 to any one of you who wants/needs one.

Hans gonna write code to get rid of the birdies? Soon, I hope because I just sent my note affirming him as crative genius to somebody at ARRL. I raved about the QMX kit and the design. He drags his feet and I will take back what I said! Har, har!
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73
Karl
KI4ZUQ