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Assembled qcx-mini 20m

 

Bring this up again, just got this assembled qcx-mini last week? but been having problems receiving and transmitting , had a fellow ham who has built a few and had a power meter to test this unit , found the troubling issues
?
1. very very low power while transmitting, would not show up on his power meter ,but signal could be seen on another radio?
?
2. transmitting on 14.062.5? his radio saw the signal on 14.064.5, the same as my test on my g90? 2 kiohz off
?
3. very low receiving , ft8 on 14.074? is not heard ,or very very low? let alone another cw station?
?
we compared all setting on his? radio to mine and all were the same?
?
so any ideas, remember this was a assembled unit??
?
Don?
KJ7SQD
?
 

Hi Don. If it¡¯s deaf and mute both you need to first check the low pass filter. Do a continuity test from the center pin of the BNC ?connector to the C29 end of L3. If that has no continuity check the toroid soldering. Let us know how that goes and we can go from there to next steps.?
73¡­¸é´Ç²Ô

On Thu, Sep 12, 2024 at 18:42 Donald - KJ7SQD via <skissler=[email protected]> wrote:
Bring this up again, just got this assembled qcx-mini last week? but been having problems receiving and transmitting , had a fellow ham who has built a few and had a power meter to test this unit , found the troubling issues
?
1. very very low power while transmitting, would not show up on his power meter ,but signal could be seen on another radio?
?
2. transmitting on 14.062.5? his radio saw the signal on 14.064.5, the same as my test on my g90? 2 kiohz off
?
3. very low receiving , ft8 on 14.074? is not heard ,or very very low? let alone another cw station?
?
we compared all setting on his? radio to mine and all were the same?
?
so any ideas, remember this was a assembled unit??
?
Don?
KJ7SQD
?
 

Under stand Ron? , will try and do that? ,? here,s my problem , i paid for a Assembled working radio and that`s not what a have ,? not very happy with QRP LAPS
sorry just venting?
?
so i`m not very good with taking stuff apart anymore, and using a multimeter ,will try though? , thanks for the advise?
?
Don
KJ7SQD
?
?
?
?
 

Don. I see you¡¯re in Chandler. I¡¯m in Peoria. I¡¯d be happy to look at it for you if you like. If you¡¯re not coming out this way for some reason you could mail it to me. My address is good on QRZ.com.? Contact me off list if you¡¯d like to discuss this.?

73¡­ Ron

On Thu, Sep 12, 2024 at 19:50 Donald - KJ7SQD via <skissler=[email protected]> wrote:
Under stand Ron? , will try and do that? ,? here,s my problem , i paid for a Assembled working radio and that`s not what a have ,? not very happy with QRP LAPS
sorry just venting?
?
so i`m not very good with taking stuff apart anymore, and using a multimeter ,will try though? , thanks for the advise?
?
Don
KJ7SQD
?
?
?
?
 

Thanks Ron , you were spot on ! I had no continuity thru L2 , tried to resolder leg of L2 and it was loose, which told me it was broken ,,? ?so i took it apart and and you could see that L2 was detached from the board on one leg...damaged in shipping i think?
?
But it`s up and working?
?
Thanks you very much
?
Don
KJ7SQD
 

Sounds good Don. Glad you got it going. 73¡­¸é´Ç²Ô

On Fri, Sep 13, 2024 at 17:26 Donald - KJ7SQD via <skissler=[email protected]> wrote:
Thanks Ron , you were spot on ! I had no continuity thru L2 , tried to resolder leg of L2 and it was loose, which told me it was broken ,,? ?so i took it apart and and you could see that L2 was detached from the board on one leg...damaged in shipping i think?
?
But it`s up and working?
?
Thanks you very much
?
Don
KJ7SQD
 

Sure happy to hear you got this going Don!!? Didn't sound too good at lunch today...
?
73
-Mike
 

For your item #2, you can adjust the displayed frequency using several methods including those in the thread below. Reverse beacon spots have perfectly matched my display since I adjusted my 20m mini.
?
Scott
 

That`s Scott,? was going to try your advise,? but after testing for power output which was 4.9
after repairs to L2 , I found that when turning on the QCX Mini I was getting a signal on my IC-7300 scope and it changed as I was turning the VFO on the QCX Mini accordingly. When listening to the signal on the IC-7300 it was high pitched and constant. turn QCX off and signal goes away. No key plugged in No speaker ,only power
?
anybody ??
?
Don?
KJ7SQD
?
?
 

¿ªÔÆÌåÓý

There might be several possibilities...

  • The QMX uses a 12kHz IF (and there's no RF amp to isolate the mixer) so you could be hearing the local oscillator... (if this were the case, there would be one peak roughly 12kHz from the receive frequency.)
  • You could also be hearing a harmonic from the internal switching supplies (I believe there would be peaks every 150kHz or so...)

From your description below, I'd suspect that you're seeing the QMX local oscillator.

I don't think you're the first to see something like this, though I couldn't tell you how to search for it!

Good Luck,
Paul -- AI7JR

On 9/14/24 16:23, Donald - KJ7SQD via groups.io wrote:
That`s Scott,? was going to try your advise,? but after testing for power output which was 4.9
after repairs to L2 , I found that when turning on the QCX Mini I was getting a signal on my IC-7300 scope and it changed as I was turning the VFO on the QCX Mini accordingly. When listening to the signal on the IC-7300 it was high pitched and constant. turn QCX off and signal goes away. No key plugged in No speaker ,only power
?
anybody ??
?
Don?
KJ7SQD
?
?
-- 
Paul -- AI7JR
 

Paul,
?
I agree with you it looks like its the LO leaking thru ?BUT...
?
1) He bought this NEW ASSEMBLED.
2) one of the LPF toroids was completely disconnected because of a broken wire solder joint and the toroid was standing up (mostly) --> that would take a lot of vibration to do that I think
3) the tx output is not on the right frequency - its ~2 kHz off (high i think )
4) i suspect it was *never* even tested or calibrated
?
So.. what Im thinking is Hans should jump in here and offer a new unit or at least have him send it in and get all "factory tested and calibrated" like it should have been. ?He has spent over a week pulling his hair out on what is going on with a NEW unit.
?
My $0.02
?
?
 

Don, the QCX mini has a local oscillator for the receiver that¡¯s 700 Hz away from the transmit frequency. It is strong enough to hear on local receivers but not strong enough to travel any distance away from your QTH. That is not an issue. It¡¯s a normal thing with direct conversion receivers.?

The 2 KHz off frequency you mentioned is probably a calibration error. It¡¯s not really possible to send one of these back to Turkey without post office issues. I¡¯d be very happy to look at this for you and bring it up to spec. You can contact me off the group at my call sign at gmail dot com to discuss if interested.?

Best 73¡­. Ron WA7GIL



On Sat, Sep 14, 2024 at 18:53 Mark - N2IU via <mark.ennamorato=[email protected]> wrote:
Paul,
?
I agree with you it looks like its the LO leaking thru ?BUT...
?
1) He bought this NEW ASSEMBLED.
2) one of the LPF toroids was completely disconnected because of a broken wire solder joint and the toroid was standing up (mostly) --> that would take a lot of vibration to do that I think
3) the tx output is not on the right frequency - its ~2 kHz off (high i think )
4) i suspect it was *never* even tested or calibrated
?
So.. what Im thinking is Hans should jump in here and offer a new unit or at least have him send it in and get all "factory tested and calibrated" like it should have been.? He has spent over a week pulling his hair out on what is going on with a NEW unit.
?
My $0.02
?
?

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