Low sensitivity and other problems

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a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Low sensitivity and other problems

Post by a1973 »

The receiver has low sensitivity or low gain. On the Tecsan PL-330 I can hear 10 times more stations and much louder. The sound from the speaker is almost inaudible. I can hear through headphones, but still weak. Reminds me of a detector receiver :) The impression is that some amplifier is not working or an assembly error. How can this be checked and corrected?

SWR meter shows strange values on 50 ohm resistive load: values depend on the band and go up to 9.99. On high frequency bands SWR is less.

I also built the receiver using the schematic from the website, and then looked at the paper schematic. The number of turns on the 3 coils differs by one turn. Do the coils need to be rewound? Can it affect the sensitivity?

Also I measured coil L15 - it has 80 µH and the schematic says 200 µH, although the number of turns is correct.
a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Re: Low sensitivity and other problems

Post by a1973 »

Soldered the board again, the receiver seemed to work better. But the other problems remain. The speaker is still quiet. SWR is 9.99 everywhere. Efficiency 95% at 3.5 MHz and 10% at 28 MHz. What does efficiency even mean?
a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Re: Low sensitivity and other problems

Post by a1973 »

Ok, I'll do a YouTube review: (tr)uSDX has a lot of problems. There is no support, the community doesn't help. I don't recommend it!
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: Low sensitivity and other problems

Post by dl6sez »

I think you have a lot of problems: no good solder technique and can't look at assembly instructions although they are accessible as videos....
so what :mrgreen:

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Re: Low sensitivity and other problems

Post by a1973 »

I know how to solder and watched the videos. The problems are not related to soldering, I just heard different numbers of stations on the band at different times of the day. But an inexpensive Chinese radio works much better. The speaker is very quiet, I will do a power tweak, but I don't think it will improve the volume much. SSB quality is poor. I tried FT8 and made only one QSO in an hour.
I'll try to adjust the filters some more, but the overall impression is bad.
The transceiver is really problematic.
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: Low sensitivity and other problems

Post by dl6sez »

The only thing is you problematecally don't know how to do things right and blame others here!
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Re: Low sensitivity and other problems

Post by a1973 »

Strange that my radio engineering degree, your videos and years of soldering experience didn't help me. :mrgreen:
vk2tty
 

Posts: 26
Joined: 26 Nov 2023, 06:35
Location: QF57UC, Australia
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Re: Low sensitivity and other problems

Post by vk2tty »

I agree it is strange that your radio engineering degree and years of soldering experience did not help you.

Checking and fixing some of your soldering helped with reception. I'm glad you gave it a shot. I reckon you should give it a shot again.

You seem upset that you're not getting enough community support. I felt like I wanted more replies, too. Eventually I figured I was mostly upset because I couldn't get my radio working by my deadline. I let go of my deadline, slowed down a little… and immediately found the information I missed reading while upset and in a hurry. Oops. I can now ask better questions that are easier to answer in a hurry.

Thank goodness I didn't take out my sore feelings on the community, acting in an antagonistic fashion guaranteed to reduce anyone's willingness to help.

If you want specific actionable help on your remaining technical problems, my advice is:
  • start a topic for each one,
  • give it a clear descriptive title
  • describe the problem, your troubleshooting steps so far, measurements etc
  • ask what your next steps are
  • come back in a week or two
If you give up, at least send me your radio. I've got an A/B testing technique I'd love to try.
a1973
 

Posts: 6
Joined: 10 Dec 2023, 22:01

Re: Low sensitivity and other problems

Post by a1973 »

vk2tty wrote: 16 Dec 2023, 11:49 Checking and fixing some of your soldering helped with reception.
I thought this was the case, but I was wrong. I soldered the board well 2 times and looked at the soldering carefully under a microscope, but it didn't change anything.

There are too many problems with this transceiver that won't get solved. For example, I've read the forum and watched YouTube videos about poor SSB quality, but nothing helped.

This transceiver has 2 pluses: it's cheap and compact. But there are too many disadvantages. But it works, we'll try to do something with it.

And thank you for helping me.
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: Low sensitivity and other problems

Post by dl6sez »

I had so many Co students at University of Ulm when i did my Masters degree in electronics that didn't really know on which side to hold the soldering iron. So a degree in engineering means nothing to soldering and known practice in finding/clearing errors in a circuit!
Don't blame a circuit you don't really have analyzed and repaired to get it working,
but this is what you champion did. You didn't manage it and blamed it therefore....

73 de Chris
Will close this topic now.
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
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