I have an external ATU made by LDG, The Z-100Plus Autotuner, connected to the rig with a short section of 50ohm cable (500mm long). I use this as the internal ATU inside the FT-450D will not tune my end fed dipole on any band.
Following on from a query by a local ham I need to explain I have been experimenting using the internal ATU within the Yaesu FT-450D at the same time as the external ATU and am having good results. I have the Yaesu internal ATU set to be in circuit both on transmit and receive (out of the box as a default the FT-450D is set to be in circuit just on transmit).
It must be stressed that I don't tune both ATU's at the same time.
The way I do it is tune up on the desired band and frequency using low power through the Z-100 Plus. This gets the load presented by the antenna to the rig within range. Then I press and hold the tune button on the rig and let it do its stuff too. A further tune on the Z-100 retains exactly the same settings. In other words the external ATU is still tuned so doesn't go through its tuning cycle again.
When I take the internal ATU out of circuit while receiving a fairly stable signal I do see the S meter drop 1 or two points. I have also switched it into circuit and found that I get a noticeable improvement in reception on very weak signals.
My belief is that both ATU's compliment each other and the only thing in the manual says "Yaesu recommend keeping the ATU in circuit all the time". My view it that the internal ATU just sees a load to match to the power amplifier and doesn't know or care that there is another ATU between it and the antenna.
I am aware that there is debate whether both ATU's should be used and certain manufacturers rig operating manuals say not to do it. I only present the results that I am seeing and that is part of what amateur radio is about - experimentation. I take no responsibility for what you do in your own shack.
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