Hi All,

I purchased some time ago ATU-10 on Aliexpress but haven't used it till now. I have 1.4 firmware which I upgraded from 1.3.

Testing tuning using 50ohm dummy load I get following results
80 SWR 1.09:1
60 SWR 1.18:1
40 SWR 1.25:1
30 SWR 1.92:1
20 SWR 2.10:1
17 SWR 2.65:1
15 SWR 3.25:1
12 SWR 3.95:1
10 SWR 4.75:1

Could you help me to trouble shoot this problem.

Looking inside I can see white silicon like substance placed on top of coils. Any suggestions much appreciated.

73 Marek

开云体育

Relay not working…

I loaded Relay Testing software and by pressing TUNE I can hear relay clicking and going through C values to L values and SW/IN SW/OUT. I don't see C or L values though as it is on ATU-100. Is this expected behaviour??

73 Marek

Marek
When you use the relay test program, you need to verify that the relay that is being tested is actually working. You need to use an ohm meter across the contacts to see if the changeover occurs on the relay being tested.?? What you are hearing is not the full test. You must measure it.

For example, when testing the 'inductor switching' relay, you need to check that the normally open circuit contact goes short when activated. You can use my Sch link on David's N7DDC Github web site. EDIT? My Sch shows the relays in the rest condition.
For the capacitor switching relays, the normally open circuit contact switches in the capacitor. With the ohm meter check that contact.
Cycle thru each of the capacitors and inductors using the test program to verify as above.

If you find a contact does not switch when testing, it might simply be the pin on the relay is not soldered into the hole. As you will have noted, the relay pins are quite short and don't protrude right through the PCB so its easy for the solder not to solder it in correctly.? .

Glenn
vk3pe

On Thu, May 19, 2022 at 12:31 AM, Glenn wrote:

Marek
When you use the relay test program, you need to verify that the relay that is being tested is actually working. You need to use an ohm meter across the contacts to see if the changeover occurs on the relay being tested.?? What you are hearing is not the full test. You must measure it.

For example, when testing the 'inductor switching' relay, you need to check that the normally open circuit contact goes short when activated. You can use my Sch link on David's N7DDC Github web site. EDIT? My Sch shows the relays in the rest condition.
For the capacitor switching relays, the normally open circuit contact switches in the capacitor. With the ohm meter check that contact.
Cycle thru each of the capacitors and inductors using the test program to verify as above.

If you find a contact does not switch when testing, it might simply be the pin on the relay is not soldered into the hole. As you will have noted, the relay pins are quite short and don't protrude right through the PCB so its easy for the solder not to solder it in correctly.? .

Glenn
vk3pe

This is helpful. I just received one today and I was disappointed in the matching. Only a few bands get below 2:1. I'll dig in and test the relays.?

I experienced something similar during the construction of an SDR tcvr. Soldering small relays can be critical.
In the case of the BPF circuit, I found that one of the relays in the 40M band was not switched on at times. I determined and replaced it with an ohm measurement, it's been fine ever since.
I removed the plastic cover of the relay with a fine saw and found that a little deformation could already be an obstacle to good contact. As Glenn writes, you need to find the wrong piece with an Ohm gauge. I had another one, but it might be tensioning in one direction, making the contact not close well. If you have the opportunity to heat all the feet together (hot air) then you can eliminate the soldering stress. But be careful not to overheat, because the legs in the plastic will make the relay easy to trash.
I wish you a successful fix.
--
Gyula HA3HZ

I went through all the bands to document it against my 80M EFHW prior to attempting to repair it.
1850 - 3.71:1
3550 - 1.22:1
5405 - 1.75:1
7050 - 1.93:1
10110 - 1.95:1
14.050 - 2.82:1
18080 - 1.25:1
21050 - 2.25:1
24910 - 2.02:1
28050 - 1.38:1
50090 - 4.70:1

My KX3 will get all of those bands to 1.3:1 or less. Yes, I know this isn't a KX3 tuner! I looked at the soldering using a loupe and some of the toriod soldering work looks suspect. The relays all look okay, but the leads are so short that most of them are merely solder blobs. I'll re-flow the enameled solder joints first in hopes of an easy win. This tuner is slated to go outside with a solar panel to charge it. Fingers crossed...

I am afraid that I still have issues with proper tuning using ATU-10.

I have installed latest FW 1.5b BETA and things marginally improved but still no tune below 1.5:1 from 10MHz upwards.

I uploaded latest testing program and going through the relays I got following values

Pos_______L uH_____C pF
0_________0_______0
1_________1.22_____122
2_________2.65_____267
3_________3.87_____389
4_________5.50_____570
5_________6.92_____712
6_________8.15_____837
7________10.6______1069
8________12.2______1220
9________13.4______1342
10_______14.9______1517
11_______16.1______1639
12_______17.7______1790

Any more suggestions what I can try to fix problem?

Thanks
Marek
? ? ? ? ? ? ?

Hi, Marek
Unfortunately, one wrong RF capacitor or cold soldering of relay's pin is enough to make all the tuner has not worked.

You can check everithing with manual mode FW and VNA but it will take a time.

Thanks David for suggestion. Do you mean that I should use S21 (losses) measure to see how things change? Can you elaborate a bit on VNA checking? Sorry I am a bit rusty in such details.

73 Marek

Marek, using simple multimeter you can check if all the L and C components switch properly.
Using VNA you can check if C increase correctly.?

Finally fixed the problem. Actually three.?

First problem was that I could not get PCB board out of the box. It was stuck. Had to risk it and use brut force (hammer!!!!) to get it out. I think PCB was cut to big for the opening in the box.

Once this was done I could check all contacts and relays working by continuity check. I found two errors. Coil 3 (0.45uH) was permanently on and last caps (2.2nF) bad soldering. Also after measuring coils I found that 5 out of 7 coild were way out of designed inductance and one of the cores should be T50-6 but it was T50-2.

After repairs ATU-10 tunes to less than 1.3:1 on all bands with 50ohm and less than 1.5:1 with 200ohm dummy load.

Attaching LongWire with 9:1 unun I got less than 1.65:1 on all bands from 60 to 10. Antenna is too short for 80m band and my QRP radio doesn't do 6m band.

So very happy with results althout it took some time to fix it. Biggest challange was to take the stuck board out the case without dammaging it.

Thanks all for help and hints what and how to proceed.

73 Marek SP9TKW

I found "Relay_Test.zip" and "Manual_Test.zip" in the Firmware directory, at the bottom of the list.? ?
(Hope this helps another newbie, like me.)



Bob? ?W7DIT