New V5 build results and calibration issues. #ubitx #ubitx-help #calibration #nextion

derek (G4VWI)
 

The following observations may be of interest to others having just got round to completing my V5 build.

1) For safety I made use of the SMT reverse polarity protection circuit by KC9ON to simplify the power supply fuse circuitry which worked very well. Two separate fuses used.

2) I  used the Kit-Projects version of the ND6T gain control. Out of three versions used this one is by far the easier to fit and is recommended as it has a 5v regulator working from the 12v line. I have used a tiny mil. spec. rotary switch instead of the DP3T switch provided. Adjust for a little more gain to allow for compensation when switching in a narrow CW filter.
 3) I have used Murata T filters with .01 caps to ground in the power lines. I was getting noise from a small brushless fan. If anyone has used a SMALL temperature switch circuit let me know. If not where have others wired their fans to? I am not keen to solder directly onto the IC.
Initial tests:
1) Out of the box the VFO was out by 1.2Khz! Others mention this but as yet no explanation has been given. To calibrate make sure you have a dummy load connected. Go into "settings" >"calibrate". Connect the PTT orange wire to ground and a carrier should be visible on your analyser, SDR or second radio display. Mine was set to under 1K bandwidth centered on 10Mhz. and no trace was visible! Widening the bandwidth still no trace until the relay was activated for the third time. Possibly a sticky relay I hope? First attempt I ended up with the tuning high. Second attempt zooming in it was near enough. The BFO calibration agreed with other published settings and was straight foward.
2) Checking the CW output on a spectrum scope  showed the resistor values were not ideal and the keying will need adjusting when CEC firmware is installed. IAMBIC B produced better results. Suggestions?
On 20Mtrs. a burst of RF appeared after the keying had completed. I am not sure if this was due to the exposed circuitry on the bench or if this is a known issue with a solution? Let me know.
3)
Checking the power output the meter (not calibrated) showed an average between 5-8 watts depending on band.
4) This V5 example appears to be much more sensitive than my V4.
5) The LM386 audio amp gives adequate output into a small Visaton FRWS-5 4 Ohm speaker.
NB: The PA's get quite warm to the touch with key down even with a larger heat sink so a small fan is advised.

I intend to add a Nextion 3.2e display. Will the saved parameters and calibration be read when updating the firmware? Has anyone added a RTC to the display yet?

Please let me know how you have got on with your V5 build and comment on any points raised.

Best wishes. Derek G4VWI.

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