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TelePost LP-100, Manual

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TelePost LP-100 Manual Download Page 23

23

Operation cont’d

Fast/Slow

This button toggles between a fast responding numerical display, a peak-hold display and starting with firmware version 1.1.47, a tune
mode. In all cases, the bar graphs remain in fast mode. The character after the numerical power readout indicates which mode you are
in. A “W” indicates peak mode, a “w” indicates fast mode and a “T” indicates tune mode. Fast mode is best for taking accurate
measurements with steady state signals, or for tuning an antenna tuner. Slow (peak) is best for CW or SSB operating. Note: The Peak
Mode is VERY fast, and can respond to a lip smack, mic button click, etc. Don’t be alarmed by this… it is normal, and allows the LP-100
to provide an accurate indication of peak power. Unless a lot of compression is used, the peak reading will be somewhat higher than
the indication with a carrier… as much as 30% depending on the ALC attack time in your rig, and power supply regulation of rig or
amplifier. Tune mode is similar to Slow mode, except that the peak hold time constant is set to 0.25 sec. The Fast and Tune modes use
the preset bargraph range in the setup section, while the Slow mode shows a fixed 13 dB range. The Tune mode locks the bargraph in
high power range.

Setup

NOTE: The screens and ordering of the screens vary slightly from version to version of the firmware. These  descriptions
are based on firmware version 1.1.47b or newer.

The calibration modes can be accessed through this menu. To enter Setup mode, press Mode and Alarm in quick succession with a
little overlap. This sounds tricky, but it’s easy to master. . 

NOTE: Starting with firmware version 1.1.44, entering (or exiting) Setup is

accomplished by holding the Mode button for about a second until the screen changes. 

Once in Setup mode, the Mode button is used

to cycle through the calibration modes. There are 8 setup screens…

Reference.

 This screen display the reference voltage from the gain/phase detector, the RSSI output from the counter AGC amplifier

and temperature in degrees F & C. It is only mainly for diagnostics. Pressing the Alarm button in this mode resets the PIC, quite useful
when flash programming the PIC. Pressing the Fast/Slow button toggles the Temp display between degrees C and F.

Dummy Load Z.

 This allows you to enter the actual Z of your dummy load before calibrating. Most dummy loads are not exactly 50.0

ohms, and this will improve the accuracy of  your calibration by providing the correct reference.

Gain/Phase Zero.

 This screen allows band-by-band calibration of the balance of the gain and phase detectors. The process simply

requires a short transmission on each band into a dummy load, and the pressing of the Alarm/Dn button (which acts as a Save button
on this screen). The Fast/Slow/Up button becomes a Reset button in this mode, clearing the currently set corrections for the indicated
band. The LP-100 automatically gathers the correction factor and saves it indexed to frequency. The built-in frequency counter
automatically determines the frequency.

Phase Slope.

 Allows calibrating the phase detector. This requires a delay line of known value. In its simplest form, this can be done by

calculating the electrical length of an existing piece of coax in the 3-10’ range, and matching the readout to the calculated length at the
frequency used for the calculation. More on this in the Calibration section. I am also working on a calibrator kit to simplify this.

Gain Slope.

 Allows setting the slope of the magnitude for proper Z at a value removed from 50 ohms. This can be done with any

reasonable known load in the 25 or 75-100 ohm range. I am also working on a calibrator kit to simplify this.

Offset.

 Provides for calibrating the low level ADC converter accuracy. The screen shows the output voltage of the detector, and the

Trim level is set by adjusting for zero voltage with no RF power applied.

Hi/Lo.

 This screen allows the matching of the direct and divided inputs to the ADC to account for any slight variations in the precision

divider. 

NOTE: This menu moved up to this position starting with version 1.1.47.

Master.

 Adjusts the overall gain for power readout for all frequencies.

Fine.

 Adjusts gain by band for power readout, indexed by frequency. Frequency is determined automatically by a built-in frequency

counter.

AL Thresh/Pwr Mode.

 Allows selection of a power threshold for the SWR alarm. The normal setting is zero, meaning that the alarm will

work at any power level. Values of 0, 0.1, 1.0, 10.0, 100.0W. This is useful for multi-transmitter contest setups where significant energy
from a nearby antenna might be present on the output of the LP-100 coupler. If the energy is from another band, the LP-100 will display
SWR, which will be high. By setting a power threshold for the alarm, it will keep the alarm from tripping on induced power. The Pwr
Mode allows selection of Net or Fwd power. Net is Fwd-Ref… or delivered power. Fwd is the total incident power (including Ref) as
displayed on typical wattmeters like a Bird 43.

Summary of Contents for LP-100

Page 1: ...1 LP 100 Digital Vector HF Wattmeter Operating Assembly Manual April 2007 TelePost Incorporated Rev C20 ...

Page 2: ... laboratory Industry Canada Compliance Statement Canada Digital Apparatus EMI Standard This Class B digital apparatus meets all the requirements of the Canadian Interference Causing Equipment Regulations Cet appareil numerique de la classe B respecte toutes les exigences du Reglement sur le material brouilleur du Canada Copyright and Trademark Disclosures LP 100 is a trademark of TelePost Inc Wind...

Page 3: ...oduction 4 Parts List 5 Assembly Instructions 8 Initial Checkout 16 Setup Calibration 18 Operation 22 Circuit Description 26 Schematic 28 Troubleshooting 30 Software 32 Specifications and CAL Table 34 Warranty 35 Appendix A 36 ...

Page 4: ...sembly to familiarize yourself with the project It is highly recommended that you thoroughly read through the Assembly section before even unpacking the LP 100 kit RoHS Statement The EU adopted a set of standards for the Reduction of Hazardous Substances in July 2006 There is considerable confusion over which devices and companies are affected by the new rules It is our opinion that home built kit...

Page 5: ...ed 105 2 C23 24 0 001 marked 102 2 C25 26 0 002 marked 202 1 C36 330pF 50V marked 331 1 D2 Rt Ang LED Red 1 D3 Rt Ang LED Green 1 D4 1N4001 1 D5 1N4148 1 RC1 ribbon cable assembly 2 J1 P1 16 pin DIL header for display 2 J2 7 BNC jack rt angle 1 J3 Power jack 2 5mm 1 J4 DB9 PCB mount 1 J6 Dual RCA PCB mount 2 JP1 2 2 pin SIL header 2 Shorting jumper 4 L1 2 3 7 470 uH 100 mA molded choke large brown...

Page 6: ...sure top bottom 1 PCB Main PCB w pre installed SMT parts 1 Heatsink Heatsink for 7805 regulator 2 IC Socket 8 pin sockets 2 IC Socket 16 pin sockets Socket not used for the relay 1 IC Socket 28 pin socket 4 Rubber Feet Square Parts to be installed coupler QTY Part No Description 1 Enclosure Coupler 1 PCB Coupler 2 T1 2 Toroid cores FT140 61 2 UHF Connector SO 239 2 BNC Connector UG1094 U 2 BNC cab...

Page 7: ...g screws black for main enclosure 1 4 x 3 8 9 53mm self tapping screw black for RCA connector 1 4 Solder Lug 2 on serial s after 200 You should check all parts before starting to allow you to start the process of obtaining replacement parts as soon as possible It is also a good idea to sort the parts in advance egg cartons are handy for this passive parts only Michael s crafts stores also have nic...

Page 8: ...venience SMT parts are supplied wherever necessary for performance or availability reasons CAUTION Be very careful handling this board to avoid damage to the installed parts Anti static measures are highly recommended such as use of an anti static mat grounded soldering iron and wrist band You may wish to clean the flux from the board after assembly although it is not necessary with most modern so...

Page 9: ... my LP 200 or the Elecraft DL 1 Alternatively you can use a pair of 50 ohm dummy loads with coax adapters to allow them to be paralleled to provide 25 ohms This calibration can be done with as little as 5W of power This adjustment is not imperative as the default value is quite acceptable SWR calibration requires setting offset and slope adjustments for the AD8302 gain detector Calibration of the ...

Page 10: ...oard flat as you go to avoid gaps q Install resistors To avoid messiness when trimming leads I would do about 6 at a time If you are unsure of the colors used by some of the manufacturers for the color code measure the value with a DMM q Install all 01 uF caps marked 103 in groups of about 6 q Install all 1 uF caps marked 104 This should be done in at least two batches On some runs these parts hav...

Page 11: ...at the enamel is removed from the leads before soldering to ensure good contact q Install L4 and L6 The remaining chokes will be installed as part of the initial checkout of the board in order to enable powering up of circuits individually These may be brown or green but are smaller than the other chokes NOTE If you check the chokes with a meter like the AADE the readings may be low This is becaus...

Page 12: ... when the first step of the screen saver timer is reached A finer adjustment can be made after the screen saver starts The correct voltage for the PLED at the junction of R8 and R15 is 3 0V at full brightness while displaying the main screen It will drop to 2 4 2 5V in the screen saver mode 35 mA q Step 3 Install L1 L3 U5 and U8 82 mA Temporarily enter the Setup mode by briefly pressing the Mode S...

Page 13: ...of the coupler The top picture is courtesy of Dario N5QVF and the lower right one is courtesy of Stan W5EWA The sequence of pictures below is from Jack K8ZOA Jack developed a clever way to ensure proper winding of the cores both for spacing and coverage of the windings Details of Jack s winding methodology is found below ...

Page 14: ...so that you will have at least two to use after printing The reduced size screen capture to the right shows what the screen should look like before printing Print the screen cut to the rules out and tape to the cores Use a white laundry marker or grease pencil to mark the lines on the toroids Jack recommends the use of a tight fitting cork to hold the windings in place as you proceed and to help f...

Page 15: ...tails on the xfmrs except for the lead that exits from the back of the voltage xfmr lower right lead in the lower right picture below which should be 3 7 62cm long shown exiting the frame in the picture Scrape the enamel off the ends of the short leads A razor knife or sandpaper is good for this Note It is best to scrape the enamel off as the supplied wire may or may not be heat strippable Wind th...

Page 16: ... a little q The xfmr should be oriented level with the windings facing up before soldering Solder the coax on the shield end into the SO 239 connector and the shield wire to the solder lug on the XMTR connector Cut the wire from the outside left of the transformer secondary to length and solder it to the lug on the XMTR connector The other end of the coax will be soldered along with the long wire ...

Page 17: ... Using the Alarm Set button set the Alarm for 1 5 Remove the dummy load and transmit into the coupler at low power The Red Alarm LED should light on the front panel and the relay should click If you have JP1 in place the Piezo transducer should also sound Note the transducer will sound pretty loud since it s not inside a case at this point Reconnecting the dummy load will cancel the alarm after a ...

Page 18: ...t is used to calibrate the slope of the gain detector It is accomplished by transmitting into a 25 ohm load and setting the Trim for a reading of 25 0 or whatever the actual load resistance is if it s not exactly 25 0 Allows adjustment of the accuracy of the op amp detector and ADC to provide correct conversion values at low power levels The screen shows the output voltage of the detector and the ...

Page 19: ...librator design which would use inexpensive 1 thick film resistors or 5 metal oxide resistors to provide switchable 50 25 ohm impedance with a 10W rating It would include a diode peak detector for measuring power with a calibrated table of voltage vs power I am also testing a method of using a 6 long length of RG 59U which when terminated with a 50 ohm dummy load produces a known complex impedance...

Page 20: ...m load after this test The expected trim value should be in the range 0004 to 0004 and will usually be even closer than that Leaving this adjustment at 0 0000 will result in a maximum error of a few tenths of an ohm Power Calibration Before starting calibration it should be pointed out that calibration is not absolutely necessary In calibrating hundreds of the assembled versions of the LP 100 it w...

Page 21: ... simply transmit on the band of interest and adjust the Dn Up buttons for the correct power readings Move through all bands in sequence until they have all been adjusted You will notice that when you transmit now the band indicator shows the band you are transmitting on and the Trim value changes automatically based on the band The Mstr Trim setting will typically be within 2 and the variation of ...

Page 22: ...play 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 measureme...

Page 23: ...of your calibration by providing the correct reference Gain Phase Zero This screen allows band by band calibration of the balance of the gain and phase detectors The process simply requires a short transmission on each band into a dummy load and the pressing of the Alarm Dn button which acts as a Save button on this screen The Fast Slow Up button becomes a Reset button in this mode clearing the cu...

Page 24: ... 0 25 to 5 seconds The shortest time can be used for amplifier tuning especially with a pulser The default setting is 2 seconds for normal SSB or CW operation Alarm User Setting Allows setting an alarm threshold other than the preset choices Any setting from 1 0 to 5 0 is permissible After entering the Setup mode these various screens can be accessed by cycling through them using the Mode button I...

Page 25: ...y if it goes down then the reactance is capacitive sign is A suitable distance is QSY is about 100 kHz or more The LP Plot program has the ability to determine sign automatically since it can control your transmitter s frequency When it plots a range of frequencies it uses the slope of the reactance curve to determine sign and plots the results accordingly It is important to remember that the impe...

Page 26: ...r a 50dB range of input power This signal feeds the frequency counter in the PIC to allow automatic frequency detection at all power levels This allows for automatic band by band calibration of the power readout of the LP 100 The AGC amp also provides a DC Received Signal Strength Indicator which is used for a number of level detection tasks within the PIC The A D converter also receives temperatu...

Page 27: ...flashed into the PIC s memory A program entitled MicroCode Loader MCLoader from Mecanique is provided to do this A Windows charting program is also available to allow graphing of any of the LP 100s parameters including Z R X SWR and phase angle vs frequency Future plans for the charting program include the possibility of a Smith Chart display and I plan to add a translation function to both progra...

Page 28: ...28 Schematic Page 1 ...

Page 29: ...29 Schematic Page 2 Coupler Schematic ...

Page 30: ... added ICs Incorrect operation of buttons Check for good ground lead connection on three tactile switches Incorrect values for RSSI or Temp Check U5 U8 for proper orientation Check output voltage of U5 at pin 6 It should be very close to 2 500 V Check for proper orientation of U7 for Temp Check soldering around U9 for RSSI Excessive current at Initial Checkout Step 4 Check the added jumper between...

Page 31: ...hich uses the well supported FTDI chipset for about 18 These adapters are both much cheaper than the ones typically sold at computer stores and should work well I have been asked about a USB port for the LP 100 and it would be easy to do but since all ham software has native RS 232 com support and older machines don t have USB ports I think a RS 232 port with an inexpensive USB adapter where neede...

Page 32: ... to flash new firmware make sure the connection between the LP 100 and PC is solid You can do this by running the VCP program MicroCode Loader works with the MCLoader bootstrap loader program installed on your PIC It allows the user to easily update the firmware in the LP 100 The correct settings for MicroCode Loader found under the Options pulldown are as shown NOTE Make sure you settings match t...

Page 33: ...33 LP 100 Plot Plot version 0 99 is available for download on the LP 100 Current Software page An html help file is also available there with instructions for installation and use ...

Page 34: ...sitivity 0 5 accuracy Power handling 1500W continuous duty 2500W peak Bargraph response 90 Hz Direct Inputs 15 to 33 dBm 50 ohms 0 1 to 650 MHz 0 1 5 dB 2W max DC Power 11 15 VDC 160 ma Operating temp range 0 to 50 degrees C Clock 40 mHz Program memory 64kB Size Controller 6 0 x 6 0 x 2 75 5 08cm x 5 08cm x 6 99cm Coupler 2 25 x 2 40 x 5 00 5 72cm x 6 1cm x 12 7cm Weight 3 pounds 1 36 kg CAL Table...

Page 35: ...arge and returned to you at our shipping expense Repaired or replaced items are warranted for the remainder of the original warranty period You will be charged for repair or replacement of the LP 100 made after the expiration of the warranty period or where in our reasonable opinion the damage is due to improper assembly of the kit TelePost Inc shall have no liability or responsibility to customer...

Page 36: ...36 Appendix A ...

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