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Pricing and specifications subject to change without notice.

LP-500 / LP-700 Digital Station Monitor
Digital Power /SWR Meter, Waveform Monitor Scope and Modulation Spectrum Display all in one.

Above picture shows the relative sizes of the LP-500 and LP-700 in comparison with other familiar pieces of equipment at N8LP.

What is LP-500?

LP-500 is a digital station monitor which displays detailed information about the transmitted signal of a station. It displays the sampled signals in numerous formats including Power/SWR, various oscilloscope type displays and a spectrum display. The sampled signals are obtained by demodulating the RF,  like in a traditional wattmeter, and should therefore work on any frequency for which there is a suitable directional coupler with the appropriate voltage scaling and time constants. It should be noted that demodulated samples are audio frequency based and not the same as RF samples. With some types of modulation, the demodulated audio is not a linear representation of the modulation signals, therefore the spectrum display works quite differently than a true spectrum analyzer. This doesn't pose a problem for AM signals, where the demodulated audio is faithful to the modulation signal, but is a challenge for SSB and other signals without a carrier. For this reason, we have developed special test signals which allow for some traditional SSB tests to be performed, although the tests cannot be directly compared to measurements from a true spectrum analyzer. In many cases, though, similar information can be gleaned for the tests, and they can be used for comparative tests to see the effect of changes to the transmitting equipment.

Both meters are in stock and shipping to customers based on seniority on the waiting list. We have shipped hundreds of meters to date, and are improving our production rate as we go.

here to get on the LP-500/700 waiting list. Please include your call sign in the subject line to make automated sorting easier, along with your preference for LP-500 or LP-700. * The current wait time for a new listing is 6 months +, but as mentioned above, we are working on improving production rates.

Open this file in Acrobat Reader to search the waiting list for your current position as we progress through the list. The file was last updated Sept. 9, 2017. Note: Call signs on the list are hidden, but you can still search for your position by entering your call sign in the "Find" menu in Acrobat Reader.

Click here for LP-500/700 User Guide in English.

Click here for the LP-500/700 User Guide in German. Translation provided by our dealer in Germany, Difona Communication (

Click here to join the LP-500/700 User Group.

 Visit Product Review page for LP-500/700

Click here for a gallery of LP-500/700 installation pictures.

Click here for Encoder Mod for very early units.
Free plug in daughtercard for early LP-500 / 700 to improve optical encoder response. Affects LP-500 with serial number below 00030, or LP-700 with serial number below 00018. Models later than these come with the mod installed. Email Larry if you would like one of these.

* The list is used to determine seniority for regular retail sales of new production units. Excludes beta units, demo units,  units used for development / testing and a small allotment of dealer orders.

September 9, 2017 - We are out of stock on LP-500 enclosures, but expect a new batch on Monday, September 12. We have stock on all other LP-500 / 700 related items.

We continue to contact list members in small groups and offer them the option of ordering one of the meters, or passing at this time.

If you were near the top of the original list and haven't heard from me, make sure I have a current email address. Here's my email. We haven't had many bounces to our email notices, but we have had some guys who didn't see the notice that was sent.

Current releases are v2.45 firmware and 1.075 VM software. To run VM v1.075, you must also install firmware v2.42 or newer. The VM now includes the WFM split screens. The firmware changes were done to support the new VM capabilities. The v2.45 firmware includes some improvements to the low power accuracy of the meter.

Firmware and software are posted in the downloads section of this page, along with firmware history, for those wishing to flash update their firmware. This is a fast and easy process once you have learned it. Instructions are in the User Guide on page 11. You can download the Bootloader program and the firmware by clicking here.

Larry N8LP

Pricing -  LP-500 pricing for the time being will stay at the original target of $650USD plus couplers (at least one required). The final cost of the LP-700 has been set at $720USD plus couplers, and will remain so. We currently offer the LPC-501 3KW PEP & LPC502 5KW PEP  HF/6m couplers, and LPC503 10KW PEP HF coupler. Others to follow over the next weeks and months. The LPC501 costs $150 ea, the LPC502 & LPC503 cost $200 ea. N connectors on any coupler cost an additional $25 per coupler. Standard connecting cables (CAT6a) are 7' (2 meters) long. Other lengths are available up to 20' (6 meters). Of course, users are free to provide their own cables of almost any length.

Watch LP-500 / LP-700 Video...

First video of LP-700, sitting side by side with the LP-500 and the LP-100A for size comparison. Due to the limitations of the HD camera, this is not a good comparison of the resolution of the displays, which is actually the same, but still a good comparison of size. This video shows the latest firmware and provides examples of some common operating and testing scenarios.

Note: The video starts in Standard Definition, but if you click on the far right icon in the toolbar at the bottom of the video window, it will zoom to full screen High Definition. With a broadband connection, the video should be smooth and glitch free, even in HD.



* Bright 5" Color TFT Display w/ 800 x 480 Resolution
 * LP-700 has a larger enclosure and a 7" Display, otherwise the two
   meters are the same.

* 32-bit Main Processor
* Touchscreen controls of all functions, plus physical
   switches for the six main function keys
* Graphics and Audio coprocessors
* (8) 16-bit / 200 ksps ADCs with Adjustable Oversampling
* Low Distortion Proprietary Custom Digital Test Signals
   to Aid in Rig & Amplifier Adjustments using
WFM and
   Spectrum Displays.
* Distinctive Aural/Visual Alarms for Each Channel for both
   Power and SWR.
* Native USB Interface - No Drivers Needed

  (not needed for normal operation)

* Flash Upgradeable
* Includes Windows based "VM" (Virtual Meter) software
   which allows computer control and monitoring of
   the LP-500 locally, or remotely using RDP or a USB Device Server.

* Fast Screen Refresh

* 12VDC Operation / 800 mA maximum.

* Interface to Rig is Through Remotable RF Couplers using
   CAT5/6 cable of any practical length.
* Provides Extensive Information About the Quality of
  Your Transmissions
* Size: LP-500: 8.0" W x 4.5" H x 6.0" D

              LP-700: 9.85" W x 5.5" H x 6.0" D

Watt / SWR Meter

* Couplers for HF, VHF, UHF...   Power up to  10KW
   (VHF / UHF available soon)

* Up to 4 Couplers with Simultaneous Sampling & Auto-Ranging

* NIST Traceable Calibration
* Large Numerals for Power and SWR at a Glance

* Simultaneous Bargraphs for Instantaneous
  Peak Pwr, Average Pwr & SWR

* "Sticky" bar displays highest peaks in all modes

* Flexible Multi-Channel SWR & Power Alarms
   w/ Adjustable Set Points
* SWR Protection Relay Jacks for 2 Amplifiers

Waveform Monitor Scope

* Full screen Waveform, Trapezoid & Scope Displays
  (Trapezoid requires two couplers)

* Adjustable Sweep and Trigger with Memory.

* 5 Presets for SSB, CW, PSK & 3 User Selections

* 5 Vertical Scales per Channel with Memory

* Multiple "Split-Screen" Displays with Combinations of
  Waveform, Power/SWR, Trapezoid and AM Modulation
  (w/ Bargraphs/Readouts for Positive & Negative Peaks).
* Touch Screen Cursors for Measuring Time Intervals & Levels
* Adjustable Peak Markers to Prevent Exceeding Preset Limits
* Freeze Button to Facilitate Touch Screen Measurements

Spectrum Display

* Displays Modulation Spectrum of Transmitted Signal,
   as sampled by the coupler *

* Adjustable Span & Averaging
* Linear and Log Frequency Scales
* Adjustable Vertical Reference with +65, +55 & +45 dBm
   Full Scale
* 18 bits Effective Resolution
* Up to 80 dB Measurement Range
* Touch Screen Cursors for Measuring Frequencies & Levels
* Adjustable Peak Level Marker

*  The Spectrum display does not sample RF directly, so results cannot be compared directly to
an RF spectrum analyzer. Useful comparative measurements can be made, however. Because
the couplers employ diode envelope detectors, signals without a carrier would normally be
distorted during demodulation. To account for this, we provide special test signals for these
modes which add subcarriers to simulate the existence of a carrier. See usage guidelines in the
User Guide for more details.

While the LP-100A couplers look similar to the LP-500 couplers, they are completely different
and therefore not compatible.

Important notice for LP-100A owners: LP-500 will not replace the LP-100A. The LP-100A
will continue with some important features not provided in the LP-500.

Preliminary Specifications…
(with LPC-501 coupler)


Power Range…                          0.1W to 3KW PEP / 1500W Average
Absolute Power Accuracy…       Better than 3% at 14 MHz, NIST traceable.
                                               (Reduced accuracy below 5W)
Flatness…                                Better than +/- 0.1 dB from 1.8 to 54 MHz
Directivity...                                >30 dB, 1.8 to 54 MHz
Return Loss...                            >40 dB, 1.8 to 54 MHz
SWR Range…                           1.00 to 9.99
SWR Accuracy…                       5%
Bar Graph Resolution...              600 steps for each range, Manual or Auto-Ranging
Number of Channels…                8 simultaneous (FWD & REF power for 4 couplers)
Channel Balance...                     +/- 0.1%
Memories...                               Range & Alarm settings are saved per channel
                                                Channel settings are saved per mode
A/D Converter                           16-bit / 200ksps, plus oversampling (2X to 16X).
DAC Resolution…                     18-bit, 96 dB SNR
Screen Refresh…                      5 Hz to 70 Hz, depending on mode, sweep/span setting.
Sampling Rate…                       2.5k to 80 ksps, depending on mode, sweep/span setting.
Display Resolution                    800 x 480 pixels (WVGA)
Display Type                            TFT with White LED Backlight
Display Size                             LP-500: 5" Diagonal, LP700:  7" Diagonal
Test Tone Output…                  250 ohms, 350-500mVpp, unbalanced, 0.01% THD into 10K load
Power Requirements…             12-16VDC @ 800 mA maximum
Size…                                     LP-500: 8.0"W x 6.0"D x 4.5"H (20.3cm x 15.2cm x 11.4cm)

                                               LP-700: 9.85"W x 6.0"D x 5.75"H (25.0cm x 15.2cm x 14.6cm)
Sweep Rate …                         1.0 to 20.0 ms/division in 0.1 ms steps
                                               5 Factory Presets and 3 User Adjustable Presets
Display Modes …                     6, including 3 split screens
Trigger Modes …                      Normal, Plus, Minus, Plus/Minus, Free Running.
AM Modulation % …                 0 to 150, positive. 0 to 100 negative.
Cursors …                               2, measuring peak voltage and time (ms)
Markers...                                1 or 2, adjustable to show preset power limits

Frequency Spans...                 2.5, 5.0 & 10.0 kHz, w/linear or log scaling
Span Multiplier...                     5X (500 & 1000 Hz, linear)  
RBW…                                   1 to 20 Hz, depending on span
Averaging…                             2X to 16X
Full Scale Reference…             +45, +55, +65 dBm
ADC Dynamic Range…            > 90 dB
Coupler Dynamic Range...        Up to 80 dB, depending on modulation type
Cursors …                               2, measuring peak power (dBm) and frequency (Hz)
Markers...                                1, adjustable to show preset power limit

Additional Couplers

Range...                                   5KW PEP / 2500W average
Flatness...                                Better than +/- 0.1 dB from 1.8 to 54 MHz
Directivity...                               >30 dB for 1.8 to 54 MHz
Return Loss...                            >40 dB from 1.8 to 54 MHz

Range...                                 10KW PEP / 5KW Average
Flatness...                               Better than +/- 0.1 dB from 1.8 to 30 MHz
Directivity...                             >30dB from 1.8 to 30 MHz
Return Loss...                          >40dB from 1.8 to 30 MHz

Additional Couplers will be available for VHF/UHF, etc.


Main Power/SWR screen showing Peak Hold power value. Also shown in the bargraphs and small numbers are continuously updating peak and average power.

Waveform screen showing keying envelope with + / - edge triggering at 30 wpm. This allows display of both edges of the envelope at the same time. You can also see a slight drop in power putput over the duration of the keying element in this case. Also displayed are adjustable cursors, which in this case show risetime of the cw envelope (1.6 ms). The cursors work in all WFM modes and measure various parameters. The freeze button makes measurements easier.

Two-tone SSB waveform using built in two-tone generator. Also shown are the peak power markers, currently set to 400W.

1/2 Trapezoid display showing amplifier overloading using built in two-tone generator. This view gives twice the resolution of a the standard trapezoid display.

Waveform / trapezoid split-screen

AM Modulation screen.

Waveform, Power/SWR split screen. We are planning to add a 2nd power bargraph to show both exciter and amplifier output at the same time.

Two-tone IMD test

Frequency spectrum of transmitted audio with white noise signal

Setup screen. The first three entries can be set differently for each of the four channels.


LP-500/700 Firmware v2.45   (Version 2.42 or newer is required if you run VM v1.073 or newer).

LP-500/700 Firmware Version History:
Note: Legacy versions can be downloaded from
Release Date
Improves accuracy of the meter at very low power levels.
Improves behavior of AM Mod bargraphs.
Adds support for VM v1.073
Adds enhanced support for LPC-502 and LPC-503 couplers in Wfm mode.
Adds volume settings in Setup for confirmation beeps. Options include Off, Low, Med, High. Made improvements to the alarm system.
Fixes Avg Pwr display in WFM modes, fixes SWR problem with VM.
Fixes alarm reset bug.
Change alarm indicators to make them more visible. See comments near the top of this page.
Adds Tune mode (like LP-100A) and supports the latest VM software release.
Fixes bug in v2.30 which caused the small blue peak number to the right of the peak bargraph to display the wrong value for time varying signals.
Added wattmeter "Peak Response" oversampling adjustment to SETUP. Choices are 50, 100, 200, 500 usec. This allows the user to decide how short of spikes he wants to allow the meter to capture.
Fixed bug with the 60 minute sleep timer choice.
Fixed bug associated with SWR Resting choice of "LAST" (wasn't displaying properly in WFM/PWR split screen).
Added more timeout options to screensaver and sleep timers, including a sleep option of "Never Sleep".
Bug fixes - WFM Range button recall value in 1/2 Trap display. CH2 Sweep recall value.
Expanded amplifier gain options to include 10dB & 11dB for amps with lower gain
Added 3W choice to AL Threshold Options and changed SWR numeric display averaging window. These changes produce more stable SWR indication while talking.
Changed SWR Rest Fmt to eliminate a choice and fix the "LAST" choice.
Fixed bug in v2.21 which didn't properly recall previous amplifier gain setting.
Adds a gain selector to the trapezoid modes to allow the user to tailor the trap width to match the gain of his amplifier. It was determined that this was needed to accommodate the latest tetrode and LDMOS amplifiers which have considerably more gain than the FCC rules have previously allowed. The range is 12 to 26dB and is adjustable in the touch screen just above the trapezoid mode buttons.
Changes the SWR display update algorithm in Peak Hold mode to narrow the range of displayable SWR variation during speech.
Simplifies alarm system. Expands call sign window to 12 characters.
Fixes alarm bug
Adds peak power readout to WFM and Spectrum screens, changes AM carrier sense window.
Fixes AM Mod bug & changes Cursor behavior in Spectrum mode.
Original release version


Required to flash new firmware into LP-500/700. See User Guide for details.

LP-500 VM v1.0.75  VM now includes the WFM split screens, and the problem with the WFM / TRAP has been addressed. Note: There are still some unfinished items to do in the VM, and there is some flicker that needs to be fixed. Requires firmware v2.42 or newer.

LP-500 VM (Virtual Meter) Version History: Note:VM is a work in progess. Many functions work, but split screens and setup are not implemented yet.
Release Date
Fixes bug in dBm value on spectrum display
Fixes Trapezoid Split Screen functionality
Adds WFM split screens.
Added support for ranges above 3KW, changes some controls to be more universal across Windows versions.
Updated installer because some users were missing a critical system file on their computers.
Changes botton colors to match meter screeen. Fixes installer problem. Note: Uninstall older version before installing this one.
Now supports all meter functions except AM & Pwr/SWR split screens, cursors and Setup
Developmental version (work in progress). Split screens and Seup page not implemented yet.