Re: KPA 1500 ATU Issue


Roger N1RJ <n1rj@...>
 

An "L" network will not match 50 Ohms to 50 Ohms. Assuming starting at an
arbitrary point, the tuner will stop when it gets within the programmed
SWR window and switch itself out of circuit. To check at various power levels,
you must have a load Z that is not 50 Ohms resistive.

73, Roger

On 7/4/2020 11:43 AM, Bob McGraw - K4TAX wrote:
A systematic approach is to start at 100 watts using the amplifier and ATU.
Allow the ATU to resolve a match and note the SWR value. Then start increasing
the drive from the transceiver in increments such as to attain 200 watts, 300
watts, 400 watts, and etc. At some point, it would seem from prior
descriptions, something in the antenna system is failing thus causing the SWR to
increase. Always question; connectors, jumpers, feed-line, balun, antenna
traps.

Further, using a known good 50-ohm dummy load, allow the ATU to resolve a match
into the load. Do this on each band. This is necessary to prove the ATU
integrity. Do the same power increment tests again. If nothing fails, then it
is most likely in the components of the antenna system. If it should fail
using the dummy load, then one can suspect a component breakdown in the ATU.

73
Bob, K4TAX

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