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QMX+ Receive sensitivity and birdies

 

Hello everyone,
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I own a factory built QMX+ and was using it yesterday on 30M and suddenly in the middle of transmitting, it seemed like I wasn't hearing receive in between sent elements. Upon further investigation, it seems like overall receive sensitivity decided to just greatly decrease. In addition, I now hear multiple birdies across multiple bands, some quite strong, together with the reduction in receive sensitivity. They are rather pure tones, and there are a lot of them across the bands.
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I reset the firmware, and the problem persists. Whatever is going on, it was something that happened suddenly. SWR was/is fine, and power out is normal. But receive is severely compromised on sensitivity an spurious tones.
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I'm bummed... any suggestions where to start??
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Joel W9JFK?
 

Joel,
I have yet to notice a drop in rx sensitivity. The birdies are present. I hope that Hans has eliminated them in the next firmware release.?
Gene KD4Y?
 

I would like to retract my previous statement of problems...
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Something is going on, but upon further experimentation, it appears to be somewhere in my external connections and not internal to the QMX+. My suspicion is that me first noticing the birdies was just a function of the receive audio being externally attenuated, whereas the internal birdies stayed the same.
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I don't think anything is wrong with the QMX+... at least nothing changed inside of it. Something changed outside of it. I shall figure it out.
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My apologies, everyone, for the false start. 5 Watt penalty, repeat first QSO.
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73,
Joel
 

A 5w penalty on a QRP rig is quite a handicap!!!
I had some odd receive issues the other day and it turned out to be a bad BNC connector.. so small hidden things can really mess with your audio.
 

Funny you should mention that ..

Had intermittent noise, glitches, sensitivity dropouts and such when testing and using my QMXs and QDXs.

Tracked that down to crap Chinese BNC tees, barrels, and couplers. Popped for only Amphenol brand. Huge improvement.?

AND ...? Have replaced the power-in jacks and plugs with 2.5mm, panel mounted screw-barrels. Bit of a kluge internally,? but rock solid on the busy operating bench. Just have to remember to take off the jack mounting nut before removing the applicable end panel.?

GREG KI4NVX?


On Tue, Mar 18, 2025 at 9:17 AM, Mike KK7MMN via groups.io
<treefrogmt@...> wrote:
A 5w penalty on a QRP rig is quite a handicap!!!
I had some odd receive issues the other day and it turned out to be a bad BNC connector.. so small hidden things can really mess with your audio.
 

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I second the Amphenol only recommendation but it’s still possible for an Amphenol connector to be bad. ?A recent book by a former owner of a major antenna manufacturing company fixed (in the early hours of the morning down in the Caribbean islands the morning before a major contest) a serious antenna issue by checking and replacing an Amphenol connector that was new in the plastic bag when installed the previous day with another one. ?Rescued the day. ?His recommendation is to test everything at home before taking it all on an island excursion. ?Being new in the plastic bag is not always ?a guarantee of quality.?

The only issue I have with the Amphenol products is that many times at various swaps the Amphenol ones are all sold by the time I get there.?

Dave K8WPE


On Mar 18, 2025, at 9:26?AM, Greg McCain via groups.io <gamccain50@...> wrote:

?Funny you should mention that ..

Had intermittent noise, glitches, sensitivity dropouts and such when testing and using my QMXs and QDXs.

Tracked that down to crap Chinese BNC tees, barrels, and couplers. Popped for only Amphenol brand. Huge improvement.?

AND ...? Have replaced the power-in jacks and plugs with 2.5mm, panel mounted screw-barrels. Bit of a kluge internally,? but rock solid on the busy operating bench. Just have to remember to take off the jack mounting nut before removing the applicable end panel.?

GREG KI4NVX?


On Tue, Mar 18, 2025 at 9:17 AM, Mike KK7MMN via groups.io
<treefrogmt@...> wrote:
A 5w penalty on a QRP rig is quite a handicap!!!
I had some odd receive issues the other day and it turned out to be a bad BNC connector.. so small hidden things can really mess with your audio.
 

Check your AGC settings?
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M
 

What should the AGC settings be?
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73
Karl
KI4ZUQ
 

Interesting thought.
Karl wrote:
What should the AGC settings be?
First just turn agc off and see if the nature of the issue changes.
If you have the first parameter turned low, like S4 or so, it could be cranking your gain up so you hear the tones much stronger than they are.? This would happen in CW mode.

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