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Dynamic signals on test points


Gerard
 

Hello,
Is there a document with a copy of the signals seen on the scope of the test points?
I did find a documentation of Ufi Auttorri but this only gives the continuous tensions on the legs of transistors.(All is good)
I don’t understand, I’ve checked everything.
I am perfect at the frequencies on clock 0,1,2. Clock 2 follows well with the reception frequency. I calibrated everything with an average frequency of 15 MHZ. (Middle 0/30Mhz). BFO is on 11996650.
The tricoils are well cabled and the phases respected.
Everything was checked with oscilloscope and frequency meter.
I also tested the frequency curve of the 45MHZ (max at 45007680) and 12MHZ filter (Max at 11998370) . I tested the amplifier and even deactivated the CAG.It works because the beat test is very strong.
SIMPLE QUESTION: WHEN YOU DISCONNECT THE ANTENNA IS YOUR BOTTOM BEAM STRONG OR NOT? (Put the audio to the max).
Mine is weak!
The inlet filter has also been tested, and even shunted for testing.
Tests also by changing the transistors of the reception part, same finding.

cdt



Evan Hand
 

Gerard,
I do not know of a document with the TP signal pictures.  Not sure if it makes much sense unless it were under specific test conditions, as mostly you will just see noise on the majority of them.

When I disconnect the antenna, the audio is ver quite.  A very slight hiss, that goes up by just touching the antenna input.

I found the attached PDF file, maybe this will help.

73
Evan
AC9TU


Gerard
 

Evan,

This is what I wanted to know with the antenna disconnected. In this case, the problem can only be at the level of the mixer with the clock2.
I’ll double-check the enteric transformer.
For the documentation, that’s the one I was talking about and that I used for tension control.
Thank's for your help
cdt


iz oos
 

Thank you for the PDF!!!


Il mar 22 set 2020 01:35 PM Gerard <kabupos@...> ha scritto:
Evan,

This is what I wanted to know with the antenna disconnected. In this case, the problem can only be at the level of the mixer with the clock2.
I’ll double-check the enteric transformer.
For the documentation, that’s the one I was talking about and that I used for tension control.
Thank's for your help
cdt


Evan Hand
 

Gerard,
You may have done this already, if you have a 50MHz signal generator, you could try injecting a low-level signal into TP13.  Depending on BFO setting, this should result in a tone.  If not, then try adjusting the signal generator up or dow to see if a tone does appear.  If so, then you are most likely correct with the first mixer potentially being the issue.

73
Evan
AC9TU


Gerard
 

Evan,

This afternoon i have all controled with a generator.
The two stages of amplifiers (Each 3 transistors). the filter 45MHZ. The scale filter 12 MHZ.etc
I  have also tested with generator on test point 13. The tone also Appear.
For me all is OK
One last test was to put the generator at 20 meters of the µBitx  with only a 20 cm thin wire 
i am picking the signal on low frquencies (1.5/ 3MHZ) without the anntenna and Stronger when connecting the antenna
I think it proves that the mixer clock 2 works and also the µBitx.
I just think the antenna is rotten!
I may have been stubborn about a fake pb.
I ordered a new antenna and maybe I’ll make myself a loop antenna.
I’m shutting down the tests for now
Thank's for your help
cdt


Evan Hand
 

The antenna makes all the difference regardless of the rig.  I have both a uBITX and a commercial Icom IC-7300.  Both have about the same sensitivity when switching the same antenna between the rigs.

I have a real challenge at my QTH as I am not allowed to put up antennas outside of the house.  All are in the attic, so very much dependant on the weather and still not very good.

Let us know how the loop antenna works out.  I have been looking at them for almost 2 years now.  From what I have read, there is an optimum size of the loop depending on the band.  The voltage rating and value of the capacitor factor into the total cost and performance.  The most expensive part is the variable capacitor if you want to run higher power than the uBITX.

Good luck and happy DX
73
Evan
AC9TU


Gerard
 

Evan,

Look this video
I have the same type of attic at home. I had thought about doing the same type of antenna. You can’t see anything from the street.
Careful for the moment, I’m just doing the reception.
https://www.youtube.com/watch?v=PYO1EnBbRHk

Look also at this video of Jeri Ellsworth. (I think it is well known in the US.) All this to say that an antenna can make sparks, so danger in the attic.
https://www.youtube.com/watch?v=adJp1zO9qfo

There are plenty of examples about youtube for loop antenna
https://www.youtube.com/watch?v=jd43_BVAsqE
https://www.youtube.com/watch?v=B-tYtbTts0s
etc
Here for example a calculator
https://on6wg.pagesperso-orange.fr/Loop%20Antennas%20and%20Calculator.htm
http://ialms.net/calculator-details.php?calculator=1

cdt


Evan Hand
 

Gerard,
Thank you for the information.  I have an MFJ-2010 Off Center Fed Dipole (OCFD) that covers 40 through 10 meters, with a small section of 6 meters that I can tune with my 7300.

When I was talking about loop antennas I was really referring to Magnetic Loop antennas.  The calculator that I have been using for cost and performance approximations is:
http://www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx

There is also a project by W8TEE and AC8GY that uses 4 loops arranged as 2 parallel in series with another pair.  Again, the capacitor is the main bottleneck, as well as the construction.  Jack has a description on his QRZ web page:
https://www.qrz.com/db/W8TEE
The details are in the project book that has just been released by the ARRL.
http://www.arrl.org/shop/Microcontroller-Projects-for-Amateur-Radio/


There is a smoke alarm in the attic, so at least we should get a warning if something lights up.

73
Evan
AC9TU


Gerard
 

Evan,

Ok. I watched these 2 videos
https://www.youtube.com/watch?v=ftEraV0RKdA
https://www.youtube.com/watch?v=oKYD8vQkpb4

Here one of the largest in the world
https://www.youtube.com/watch?v=j-cN-ebsxbE

The antenna loop of Jack is beautiful. The hardest is to make perfect circles. I wondered if it should not be put like a metal paint to protect the tubes from corrosion.
Have a good day


Evan Hand
 

Thank you for the videos.  I wish that I could get my antenna as high as any of the three shown.  

As to coating the copper pipe, I do not believe that would be necessary.   At the worst, the copper will turn green, however, copper oxide still does conduct.  As long as you are OK with how it looks, there should not be a problem with the operation.

73
Evan
AC9TU