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Hey guys, I have a ATU QRP-40 ATU. It is pretty much the same as the ATU-100 but it maxes out at 40 watts. Here is my setup:
Rig: uBITX
ATU: ATU QRP-40
Ant: Endfed random wire 35' with 9:1 UNUN

When I hook up a key for CW and send something to kick the uBITX into transmit the screen on the ATU appears as:
PWR: 14W
SWR:9.99
ANT: 4.7W
EFF: 33%?

This tells me that I could use a better antenna, however I don't know if the ATU is actually doing any tuning. I really don't want to be transmitting with an SWR of 9.99 hitting my rig. Not so good things could happen.

hi Aaron,
what shows the ATU if you send to a dummy??
It happens that tuning fails if the SWR is too high and no match is possible with the existent components. For testing use some yards coax to a resistor other than 50 ohms ( i.e. 33 ohms). It will try to tune the cable at the ?false“ impedance if the ATU is ok. It may be useful to try different frequencies depending on the length of the used cable to get a useful result. If it finds at least one perfect SWR , the ATU is ok and you should take a closer look to your LW and UNUN.
73, Immo

With a 50 ohm dummy load it is showing the exact same thing. I really don't understand what you want me to do with the coax.?

hi Aaron,
the use of a piece of coax of Z=50ohms to a resistor of 33ohms will result in SWR greater than 1.3 and should initiate a tuning to SWR better than 1.3. This a functional test for the ATU. Dependent to frequency you will get different constellations of used C and L.
If you use your SWR-meter in series you also would be ?able to see the result… ok?
73

Aaron,

Are you sure the ATU is in automatic mode?? If in one of the other modes, it may not tune regardless of the mismatch.

73
Evan
AC9TU

Hey Evan, are you following me lol
I'm not sure what mode it is in

Hi Aaron,

I am not stalking you intentionally.? You are asking questions on the groups that I read almost daily.? I am retired, so I have a lot of time available and a lot of interest in radio.

The ATU will go through 3 stages on pressing the tune button.? Be sure that the SWR=TUNE is lit when you need to tune the antenna.? It does not seem to tune as some other ATUs do automatically.

73
Evan
AC9TU

Evan is awesome, he has saved my shack more times than I can count.?

I believe that I have it in TUNE mode. Now it says:

PWR:9.9W
SWR:5.3
ATN: 4.5W
EFF: 84%
I can hear a relay kicking in when I provide power.?
When I'm not providing power it says:
PWR=0.0W
SWR=0.00
L=1.50uH
C=22pF

When I hook up the dummy load and apply power it says:
PWR=8.4W
SWR=2.78
ANT: 2.3W
EFF=50%

I'm not liking this the way that I thought I would.?

Aaron,

Try pressing the Tune button until you get the SWR=Tune for the dummy load, then apply RF.? I believe the logic assumes you have the same antenna connected for a given frequency, so it does not tune the dummy load.? Even so, I have found the need to add the "bypass" switch as the auto mode has difficulty finding a match with a 1:1 dummy load.? Look for how to add the bypass switch in the group messages.

73
Evan
AC9TU