On Sat, Apr 29, 2023 at 6:32?PM Kent Trimble, K9ZTV <k9ztv@...> wrote:
There is a caution to be remembered in this
regard and it has to do with having two ATUs in the
circuit.
A transceiver can be used barefoot through the LA-1K
provided the external ATU (HF-AUTO or whatever) is the active ATU
in order to protect the LA-1K.
There have been instances where hams have puttheir
external ATU (HF-AUTO or whatever) in OFF or BYPASS, believing
they could then use the transceiver's internal ATU to do
the matching.
Paul warned against doing this in a similar discussion a year or
so ago, and the caution is printed in the HF-AUTO manual:
Bypass
modebypasses
the matching network.? Some users have the tuner in Bypass
allowing them to use their radio’s internal antenna tuner.? Caution is needed in this last case if
an amplifier is in the circuit and turned off or in
bypass. The standing waves (SWR)
will potentially have high voltage nodes that can cause damage to the bypass components in
the amplifier.
In
short, when operating a transceiver barefoot through the
bypassed LA-1K, the operative ATU should remain the external
ATU, not the transceiver's internal one (which should be
disabled).