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Operation
Operation of the LP-100 is straightforward, and designed to require a minimum of input once set up and calibrated. There are only three
buttons which are used in combination to access all the menus on the LP-100. There are five main modes for the LP-100, which are
accessed by momentarily pressing the “Mode” button. Pressing the button in mode 4 returns you to mode 1. The mode status is saved
in non-volatile memory, and the LP-100 will return to the saved mode upon powering up. There is also an automatic two-step screen
saver mode which dims the screen after approx. 30 sec of inactivity, and marches your call sign across the screen after approx. 2 min.
of inactivity. This is done to extend the life of the PLED display.
Mode
There are five selectable modes… Normal, Vector, dBm, Field Strength and Compression. A sixth mode which display relative power
and phase between phased array elements or stacked beams is in the works as well.
Normal
mode is designed to display all the information you normally need on one screen. It displays power in three auto-ranging scales,
and SWR, plus bar graphs for both.
Vector
mode displays Z, Phase angle of Z, X and R. These values are relative to the “LOAD” connector, not the antenna. Antenna Z
can be calculated by knowing the feedline length and using a program like TLW, or a Smith Chart. Note: The LP-100 cannot determine
the sign of X automatically.
dBm
mode uses professional dBm and RL (Return Loss) instead of watts and SWR to indicate power and load quality. The resolution
is 0.1 dB for both. The range is +15 dBm to +64 dBm, and RL from 0 to 49.9 dB.
Direct/Field Strength
mode is similar to dBm mode except that it is calibrated to display power from –15 dBm to +33 dBm. There is no
return loss in this mode because it does not utilize the coupler. Power is supplied directly to one of the inputs on the back of the LP-100.
This mode can be used for accurate low power bench measurements, as in checking the output to a transverter or the level of a local
oscillator of mixer. It is also very useful for doing antenna field strength measurements, as in checking a beam pattern. This requires
feeding a small pickup antenna to one of the inputs. The LP-100 could be set up in a field, connected to a laptop computer with wi-fi,
and the results can be read over the wireless LAN back in the shack. This eliminates any wiring that could distort the pattern.
NOTE:
The maximum power for the direct inputs is 1W continuous.
Comp
is a recent feature still under development. It displays peak and average power, and a dB ratio of peak/average. This can be
useful for determining “talk power” and can be helpful in setting a compressor/clipper, or comparing such circuits. I am working on a
better algorithm for the average reading that will be more stable. This feature will be operational in a future release of the firmware. All
firmware and software upgrades for the LP-100 will be available for download from my website. The firmware upgrades can be easily
flash programmed through the serial port with the supplied software.
Alarm
The Alarm button is used to set the SWR alarm set point. There are 6 choices… OFF, 1.5, 2.0, 2.5, 3.0 & User. The User setting is
adjusted in Setup/CAL mode. Holding the Alarm button will advance the choices every half second or so. Tapping the button will put the
Alarm in “snooze” mode for a minute. Tapping again during tuning will extend the function another minute. This allows adjusting an
antenna tuner without the alarm going off, but it returns to normal after tuning to protect the amplifier as intended.
Summary of Contents for LP-100
Page 28: ...28 Schematic Page 1 ...
Page 29: ...29 Schematic Page 2 Coupler Schematic ...
Page 36: ...36 Appendix A ...
