ATU-100 EXT Display blacks out when tuning with higher power as frequencies get higher and SWR is initially larger

Dfinitski / N7DDC-ATU-100-mini-and-extended-boards

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ATU-100 EXT Display blacks out when tuning with higher power as frequencies get higher and SWR is initially larger #93

Closed kostecky closed 2 years ago

kostecky commented 2 years ago

Hi there,

I have an atu-100 that works great, except when you start trying to tune at higher powers 20-100Watts when frequencies @ upper end of 14 Mhz -> 50 Mhz, the LCD display cuts out, but the tuner still works.

If I cycle the power, the LCD comes back on and the tuned values are there.

Is this a known phenomenon? I assume it's because of some sort of voltage spike or drop. Can I solve this with a well-placed cap somewhere?

Thanks!

kostecky commented 2 years ago

The key points are that it tends to happen:

at higher powers (20-100W)
with higher frequencies where SWR is larger and more time spent switching caps/inductors to find a match
and ONLY after a match is found and the last relay clicks

As soon as it finds the tune, the display cuts out until I power cycle, but the tuner continues to function and it does it's job.

kostecky commented 2 years ago

Nevermind, I fixed it. I put a 100nF cap between the VCC and GND pin on the display and it's stable as a rock. I imagined that it was voltage fluctuations more than the board can handle.

Thanks!

Dfinitski commented 2 years ago

Thanks. That is RF interference to the display controller. Also use shortest straight path for displays wires .