Adjustment and Configuration Manual

db4ple edited this page Apr 10, 2018 · 71 revisions

Essential Calibration and Setup Steps

Once you finished the assembly and loading the firmware, you should run through a number of important setup steps and calibrations. There are plenty more things to configure, but the ones listed here should be done initially. And in most cases, you will not have to touch these again unless you modify the hardware or the firmware improves and you are asked to re-calibrate.

  1. Input Test
  2. Touchscreen Setup
  3. SWR Meter Reverse/Forward Orientation
  4. TX PA Calibration
  5. TX/RX IQ Balance Calibration
  6. SWR/Power Meter Calibration
  7. Voltmeter Calibration
  8. Frequency Calibration

Input Test

You should as first action test if all buttons and encoders are working as expected. Holding down any button during startup will bring you into the "INPUT TEST SCREEN". If this screen comes up each time you power on, you have a badly wired button or another hardware issue (solder bridge, defective gpio pin). The "Keys Initial" value represents the press keys at startup time. If you don't press a button but still "Keys Current" and "Keys Initial" show the same value, you have "stuck" keys. "Keys Current" must be "00000000" if no key is pressed.

Press each of the buttons and see if the display reacts to this. At least the "Keys Current" value must change if you press a key. In most case you should also see the function name of the button shown on the display (in some configurations some buttons don't have a function, then you don't see the function name). Turning the encoders should give you the correct direction of your turning action and the number of the encoder.

Last but not least you can test if the screen responds to touch actions. Even without calibration you should see some coordinates display if you press on the touchscreen. If you see "Touch (no cntlr)" but no coordinates, then the firmware cannot speak to the touchscreen controller via SPI. This is in general a wiring / hardware issue you should fix.

Touchscreen Setup

If you added touchscreen connections, check if the touchscreen is working correctly using the following procedure

Skip this if you don't have the touchscreen connections fitted.

  1. Touch screen at any point while simultaneously pressing the boot button to start the machine
  2. Keep touch screen pressed until screen with calibration information appears
  3. Follow the instructions on the following screens (which involves calibration by touching several points on the touch screen with your touch pen or fingers)
  4. After the calibration procedure, enjoy the touchscreen functions!

SWR/Power Meter Reverse/Forward Orientation

If you finished the PA and you can measure HF output coming out of the mcHF in Tune mode, but SWR meter does not show a proper SWR and no power is shown on the meters of the mcHF, you most likely will have to switch the orientation of the SWR meter in software. Go to the "Configuration" menu and set "SWR/PWR Meter FWD/REV Swap" to "ON".

PA Power Calibration

What you will need:

  1. Operational PTT switch connected to the microphone/ptt connector or CW paddles connected to the CW keyer port
  2. An ampere meter OR a power supply with sufficiently accurate current measurement (minium resolution 10mA)
  3. A dummy load capable of handling at least 10W or more (20W or more recommended). If dummy load is not available, an alternative is an antenna (then calibration should be done only in the antenna bands and with an SWR meter to verify low SWR)
  4. [Optional] HF Power Meter
  5. [Optional] Oscilloscope

Basic BIAS Adjustment for mcHF RF Board (upto version 0.6)

  1. [Optional] Connect dummy load or antenna. Since no actual RF is being produced if everything goes right, the mcHF doesn't have to be connected to a dummy load or antenna. But to play safe, it doesn't hurt and is required for the next calibration steps anyway.
  2. Connect a microphone or cw paddles to your mchf.
  3. Put an amperemeter in the positive power supply line (range 2A) and switch on mcHF
  4. Choose mode LSB or USB, the band is not important.
  5. Make sure nothing is connected to the extern line in port of the TRX.
  6. If you use a microphone wit PTT switch, choose TX audio input to be coming from one of the "Line In" sources by long pressing M3 (multiple times). The TX audio source should show L>R (line in right channel) or L>L (line in left channel). If no microphone is connected, MIC (microphone) TX audio source will work too.
  7. Enter "PA Configuration Menu", "PA Bias".
  8. Setting must be "0" (if not - correct it after pressing PTT briefly).
  9. Press PTT or CW paddle. It is important that no RF is being produced.
  10. The measured current at this point is the "start mark", write it down. Be sure to have the PA Bias set to the lowest possible value.
  11. Now adjust bias so that measure current is 500mA higher than this "start mark". E.g. you measure 460mA in the previous step, so the target current is around 960mA (460+500).

FAQ PA Bias

Q: I am not able to reach the 500mA increase even at PA Bias value 115. What can I do?

A: Be sure to use none-defective, genuine RD16HHF. If one of the 2 PA mosfet is defective, for obvious reason, it is difficult to achieve the 500mA current increase.

Q: I checked, both MOSFETs are okay. What can I do now?

Some RD16HHF required a higher bias voltage to achieve the desired bias current. A modification to the bias voltage regulator U18 can help here. A resistor of 3k3 between pin 1 and 4 increases the bias voltage range by 0.8V. If this is still not sufficient use 2k2, which provides an increase of 1.2V. If these modification still not get you into the 500mA, check the PA transistors again and consider replacing them.

TX: RF Power Adjustment

Before this step the PA Bias must be set using the previous steps.
It is mandatory to connect a dummy load or properly tuned antenna. You will need a way to measure the generated RF power. Best is to use an oscilloscope or proper RF power meter. The power meter of the UHSDR TRX can be used. But since it is not calibrated initially, it is only a rough estimation tool.

The standard mcHF supports 160m to 10m operation, although 160m transmit into an antenna without additional LPF between PA and antenna is not recommended. It is recommended to calibrate all bands from 160m to 10m.

5W Power Adjustments

The mcHF is able to produce more than 5W on most bands. However, best signal quality is achieved with 5W or less. All power levels below 5W are derived from the 5W settings, thus it is important to calibrate the 5W setting properly.

  1. Choose mode LSB or USB.
  2. Set "PA Configuration Menu", "Tune Tone" to "Single".
  3. Set "PA Configuration Menu", "Tune Power Level" to either "5W" or to "as TX PWR" and change TX power to "5W"
  4. Enter "PA Configuration Menu", "xxm 5W PWR Adjust" (replace xx with your bands 10, 12, ... ,160m). You will be able to change the value for a band only if the band is selected!
  5. Press F5 - "Tune".
  6. Make sure you see "5W" as power indication in the blue "TX power" box. If not, see step 3.
  7. Set gain to achieve 5W of output power.
  8. Press F5 - "Tune" again.

TX: Adjustment For Maximum RF Power

Procedure to setup RF power in Full Power menu for each frequency band you intend to use, the standard mcHF supports 160m to 10m operation, although 160m transmit without additional LPF between PA and antenna is not recommended.

  1. Choose mode LSB or USB.
  2. Set "PA Configuration Menu", "Tune Tone" to "Single".
  3. Set "PA Configuration Menu", "Tune Power Level" to either "Full" or to "as TX PWR" and change TX power to "Full"
  4. Enter "PA Configuration Menu", "xxm Full PWR Adjust" (replace xx with your bands10, 12, ... ,160m). You will be able to change the value for a band only if the band is selected!
  5. Press F5 - "Tune".
  6. Make sure you see "Full" as power indication in the blue "TX power" box. If not, see step 3.
  7. Set the gain up to the point, where RF power stays at maximum and only DC current increases
  8. Reduce the gain back to get approximately 1dB less RF power (down-to 79%). To avoid possible instability of the PA a setting power back -1.5dB (down to 70%) is recommended.

Using the integrated two tone signal generator, you can also adjust for nice looking two tone signal with an oscilloscope instead of using the above procedure. You will have lower maximum output power settings when using this method, since it will keep you in the (more) linear range of the PA.

TX: Adjustment RF Power Meter

The RF Power Meter should be calibrated to show proper values. Calibration needs to be done for some but not all bands, the software calculates the values for other bands.

  1. Choose mode LSB or USB.
  2. Choose 5W power
  3. Set "PA Configuration Menu", "Tune Tone" to "Single".
  4. Enter "PA Configuration Menu", "xxm Coupling Adj." (replace xx with 15, 20, 40, 80 ,160). You will be able to change the value for a band only if the band is selected!
  5. Press F5 - "Tune".
  6. Set the coupling up to the point, where RF power meter shows roughly 5W.

TX: FM And Digital Modes

Please, keep in mind that transmitting FM or digital modes means there is a continuous carrier of a chosen power present at the RF output. It is highly advisable to have an adequate cooling of PA stage.

IQ Calibration

In the real world certain hardware-related influences affect the analog IQ signal in the mcHF. It is not perfectly symmetrical and the phase may not be exactly 90 degrees and/or the amplitudes may not be exactly equal. In the software domain we can use calibration to reduce/correct this problem. This requires careful adjustment of IQ phase and gain balance both for the RX and TX signal path. The mcHF from version 1.5.7 provides 3 groups of adjustments. 2 groups are for receive and transmission in a given translation mode. The third group is for adjustments in case of CW transmission (and all other untranslated transmission, which is not recommended). First of all make the adjustments in USB and translate mode. When complete, continue through the adjustments for CW mode. The CW mode adjustments do not use frequency translate, these are different software parameters to USB translate mode, so follow the adjustments through to the end. For receive only, there is now [Valid from 1.5.8] the ability for an automatically adjusted IQ phase and amplitude imbalance correction (see point RX IQ adjustments).

TX IQ Adjustments [Valid from 1.5.2]

You will need a SSB receiver for 80m and 10m, or an spectrum analyzer for this frequency range. The instructions are given for a frequency translation of -12khz. If you want to use a different translation frequency, it is recommended to run the procedure in the desired translation mode. While the overall approach is the same, frequencies will change, so if in doubt, we recommend to stick to -12kHz translation.

Preparation
  1. Set the frequency translation to -12khz
  2. Set power to 0.5W
  3. Connect dummy load or attenuator, if nothing else is available, use an antenna.
  4. The mcHF is always used to transmit the signal in USB mode!
  5. The second receiver is always used to receive the signal in LSB mode!
TX 80m calibration (translated mode)
  1. Switch mcHF to 80m band.
  2. Switch to USB mode. To switch to USB from LSB use a long press on the Mode button.
  3. Set the mcHF frequency to 3.624.000 Hz.
  4. Start "Tune". You should now be able to listen to the generated signal on a second receiver (LSB: Dial Frequency of second receiver 3.625.500, USB: 3.624.000). It should have a good strength (around S9).
  5. Tune second receiver to 3.600.000 Hz, LSB (!!).
  6. You should be able to hear a much weaker tone. Maybe you have to change the frequency of second receiver +/- 500 Hz for getting the tone in reasonable frequency. A spectrum analyzer or IQ receiver will show the weak signal around 3.599.250 Hz.
  7. Enter the "Configuration Menu", go to the "TX IQ Phase (80m)" setting.
  8. Now change the value so that the tone can no longer be heard or is minimal. The direction to change values depends on your mcHF, e.g. you may need to set a positive or a negative value.
  9. Once you found the minimum using the "TX IQ Phase (80m)", and you still hear something, use the "TX IQ Balance (80m)" setting to further reduce the tone.
  10. You may vary both settings alternatively slightly to find the best setting.
TX 10m calibration (translated mode)

You simply repeat all steps for the 80m band. Only this time in the 10m band and using the TX IQ Balance/Phase 10m settings. The initial USB frequency should be 28.124.000 Mhz (Receive for monitoring original TX signal is LSB: 28.125.500, USB: 28.124.000). The second receiver's LSB (!!) frequency for calibration purposes is 28.100.000 khz. A spectrum analyzer or IQ receiver will show the weak signal around 28.099.250 Hz.

CW TX 10m/80m calibration [from version 1.5.7]
  1. Set USB mode on mcHF. (Yes!)
  2. Set Frequency Translation to OFF
  3. Set LSB mode on second receiver.
  4. Set mcHF and second receiver to 80m: dial frequency 3624.00 kHz. Now minimize received signal using CW TX IQ/Phase settings for 80m.
  5. Repeat the last step for dial frequency 28.124.00 kHz and minimize with CW TX IQ/Phase settings for 10m..
  6. Restore original frequency translation mode.

Do NOT use CW for setting this because of the settings for frequency of second receiver would differ. Why make it complicate if it can be done simply?

RX IQ Adjustments [Valid from 1.5.2]

There are two ways to adjust for IQ phase and amplitude imbalances in RX:

  1. Automatic IQ correction [Valid from 1.5.8]: Just go into the Configuration Menu and switch "RX IQ AUTO CORRECTION" to ON. Ready to go! No more adjustments required. This can achieve up to 65dB of mirror rejection! Thanks to Yves HB9EWY for doing a real and reliable measurement! If you believe you can do it better than 65dB with your hands on your mcHF, you will have to do the manual IQ phase and amplitude imbalance adjustment:

  2. Manual IQ correction: You will need a signal generator for 80m and 10m. If you use a normal transmitter with a tune signal, use USB mode on that transmitter. Make sure you receive the strong main signal on the original RX frequency before searching the weak signal on the secondary frequency!

Preparation RX Manual IQ correction
  1. Get the frequency translation to -12khz (after calibration you may set any value you want)
  2. Connect signal generator to mcHF (maybe via attenuator regarding output of signal generator) or make sure you can receive your transmitter with sufficient but not too high signal level.
  3. The mcHF is used to receive the original signal in USB mode, the secondary signal in LSB mode !
  4. The signal generator is always used to transmit the signal carrier at the given frequency!
RX Manual IQ correction: 80m calibration
  1. Set the signal generator to 3.601.000 Hz in the 80m band (If using a second TRX: 3.600.000 Hz in USB mode, activate Tune mode).
  2. Switch mcHF to 80m band at 3.600.000 Hz.
  3. Switch to USB mode. To switch use a long press on the Mode button.
  4. You should be able to receive the generated signal with the mcHF.
  5. Tune mcHF to 3.624.000 Hz.
  6. Switch to LSB mode (!!) by a long press on the Mode button. If necessary, adjust +/- 500Hz for getting tone in reasonable frequency, if not right on spot.
  7. You should be able to hear a much weaker tone.
  8. Enter the "Configuration Menu", go to the "RX IQ Phase (80m)" setting.
  9. Now change the value so that the tone can no longer be heard or is minimal. The direction to change values depends on your mcHF, e.g. you may need to set a positive or a negative value.
  10. Once you found the minimum using the "RX IQ Phase (80m)", and you may still hear something, use the "RX IQ Balance (80m)" setting to further reduce the tone.
  11. You may vary both settings alternatively slightly to find the best setting.
RX Manual IQ correction: 10m calibration

You simply repeat all steps for the 80m band. Only this time in the 10m band and using the RX IQ Balance/Phase 10m settings. The initial RX frequency should be 28.100.000 Mhz, USB, signal generator set to 28.101.000 Hz (TRX: 28.100.000, USB, Tune Mode). The secondary RX frequency for the mcHF is then 28.124.000 khz LSB (!!).

SWR/Power Meter Calibration

In order to have the SWR/Power meter to be more accurate, you may want to run the calibrations below. Default values are often good enough to start with but the mcHF can be fairly accurate if calibrated properly.

Calibrate Zero Power Offset

Preparation: You have to make the resistor-change modification to the SWR hardware circuitry. If you haven't done so, the mcHF will show a message in the boot screen.

  1. You should have done at least the PA BIAS calibration.
  2. Connect dummy load. Better safe than sorry.
  3. In Configuration Menu set "Pwr. Display mW" to "ON"
  4. Set Input to DIG, with no USB cable connected
  5. Set mode to USB or LSB
  6. Key the transmitter by pressing PTT
  7. Adjust in Configuration menu the setting "Pwr. Det. Null" so that the displayed mW power values are flickering between 0 and 2 max. Do not go lower than necessary to achieve that.
  8. In Configuration menu disable "Pwr. Display mW". It will be disabled on next boot in any case.

Calibrate Power Coupling

You will need a good power meter or oscilloscope in order to measure the true power emitted by the mcHF.

  1. You should have done at least the PA BIAS calibration.
  2. Connect dummy load which can handle at least 5W.
  3. Set TX power to 5W.
  4. In Configuration menu enable "Pwr. Display mW".
  5. Set mode to USB or LSB
  6. Select lowest band you want to transmit in (80m).
  7. Go to the PA Calibration menu to the "80m Coupling Adj." setting.
  8. Press Tune. Align as closely as possible the displayed mW value for forward power and measured power by changing the setting.
  9. Repeat this for 40m (60m), 20m (30m), 15m (10m, 12m, 17m). Bands in parentheses are using the same coupling factor.

Frequency Calibration

The Si570 is fairly well calibrated, yet even 10ppm accuracy mean 100 Hz @ 10Mhz and almost 300Hz at 28Mhz. The mcHF firmware permits to fine tune the calibration. Equipment needed:

  • Either an as exact and as high as possible reference frequency signal (single carrier, no modulated signal OR a strong broadcast station) (RX calibration approach)
  • OR a precise frequency counter (TX calibration approach).

Preparation: Bring the mcHF upto the normal operating temperature of the TCXO (can take up to 15 minutes).

Frequency calibration can be done either in TX or in RX mode and has only to be done in one of the modes, not both! The calibration -once done and saved- is then valid for both: RX AND TX.

TX calibration approach [from firmware 1.5.8]

  1. Set a "FM" mode (FM-N or FM-W)
  2. Set input to DIG, do not connect USB cable. Alternatively you may also use any other input mode, be sure to have no input signal.
  3. Connect frequency counter to mcHF Antenna port (via attenuator)
  4. Start "Tune"
  5. Go into the configuration, item "Frequency Calib.". Now change the PPM value so that frequency counter displays frequency shown on mcHF display.
  6. Save configuration by long press on "MENU" or "EXIT" button (F1)

RX calibration approach [from firmware 1.5.8]

  1. Set demodulation mode to "SAM"
  2. Tune into China Radio International on the 16m or 19m band (do this at daytime). You can take any other broadcast station, but China Radio International/Radio Romania Intl are well known for being exactly on the accurate frequency. Many broadcast stations are NOT on the accurate frequency, e.g. Voice of Turkey, Voice of Iran, most (if not all) Brazilian radio stations etc. Alternatively use a well-calibrated signal generator with a frequency as high as possible (28MHz).
  3. Wait until the SAM demodulator has captured the carrier and the carrier frequency is displayed in the small frequency display and the small frequency display is stable
  4. Go into Configuration menu to "Frequency Calib." Adjust the PPM value until the small frequency display shows exactly xxxxxx.000 Hz
  5. Save configuration by long press on "MENU" or "EXIT" button (F1)
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