Calibration of the transmitter power in the 2M band

[SQ7ECZ]

Yes.
I tested the power on the original software.
Power meter indication:
Low - 1.4W;
Low Mid- 8w,
MID - 22W
High - 35 W

[G4EML]

That is strange, the new firmware should be using the same calibration values as the original firmware, so the top three power levels should be the same or at least very similar. Low powers will not be accurate because there is no calibration data for them. The radios I have tested seem to behave correctly but for some reason yours does not. There are calibration points for several frequencies across the whole working range of the radio. And the firmware interpolates between these to get the power settings. I am wondering if your radio has some strange value outside the 2M amateur band, or maybe it was never fully calibrated, and that is causing problems with the interpolation. We don’t have a simple way of viewing or changing the calibration yet, so the only way to see that would be to reload the original firmware and display the calibration screen in the original CPS by pressing <control> T .

Colin.

[SQ7ECZ]

Colin probably is as you write.
I am a 3 user of this device.
It came to me as "brick".
I'm not sure if there are correct calibration data.
I came back to the factory software to check calibration. I do not have a reference point.
Did any of my colleagues use a calibration table
From your MD9600 in version V2?
For comparison.

[G4EML]

If you post the calibration file from your radio I will have a look at it and see if I can see anything unusual.

To save the calibration file you need to do...

Load the factory firmware.
Connect the radio and run the factory CPS.
Press <Control> T to bring up the calibration screen.
Save the calibration file.

Colin.

[SQ7ECZ]

This is my calibration file packed ZIP

Kalibracja_MD9600 -07022022.zip

(590 Bytes) Downloaded 129 times

[ON6XX]

Hello, Just for info with my version 2. I have tried to map my power with the +W- user power settings. I arrive at the following results.


VHF 145Mhz

100mw : Between 800 & 900
250mw : Between 800 & 900
500mw : Between 800 & 900
750mw : Between 800 & 900
1W : Between 800 & 900
5W : Between 900 & 1000
10W : 1000
25W : 1100
40W : 1400



UHF 435Mhz

100mw : Between 400 & 500
250mw : Between 500 & 600
500mw : 600
750mw : Between 600 & 700
1W : Between 600 & 700
5W : Between 800 & 900
10W : 1100
25W : 1400
40W : 2500

[I1KDO]

Hi everyone
as promised I made the power measurements on all frequencies in order to better understand how it behaves in the general spectro.

Supply 14,5 Volt, Dummy load 50 ohm FM mode

Power 100--250--500--750--1--5--10--25--40

430 Mhz 100--500--1,2-- 2,5-- 4--5--9--15--20
435 Mhz 100--400--1--2,2--3,5--5,5--10--16--25
440Mhz 150--700--800--2,8-- 5--6,5--12--17-- 22
450Mhz 250--800--1,6--3--4--7--12--18--30
460Mhz 800--1,5--2,8--1--6-- 8--14--20--32
470Mhz 2--4--6--9--12--15--18--21--28


140Mhz ,,--50m--100--150--250--450--3--15--31
145Mhz ,,--,,--20m--50m--100--150--2,5--18--40
150Mhz ,,--,,--,,--20m--50m--100--2,6--20--40
155Mhz ,,--50m--70m--100--250--400--3--21--36
160Mhz 200--260--550--800--1,2--1,6--5--20--30
165Mhz 10m--20m--50m--70--100--250--1,5--10--40
170Mhz ,,--,,--,,--,,--,,--100--150--3--45
175Mhz ,,--,,--,,--,,--,,--20m--50m--800--30

,, = Low not measure
MD9600 G Ver 2.1 S/N 1809E00XYZ



73
I1KDO Lorenzo

[G4EML]

I think those figure just show that the power calibration is a difficult subject. The gain of the PA stages varies significantly across the frequency range.
The hardware does not have any way of measuring the output power, so the control is by an open loop with no feedback. It will never be very good.
I will have another look at the calibration code to make sure it is doing what was intended. There may be a bug still hiding in there somewhere.

ON6XX... You can get finer control of the User power setting by holding the SK2 button on a GD77 or the P1 button on the MD9600. That will then allow adjustment in steps of 10.

SQ7ECZ... I have copied your calibration file and will have a look at it.

Colin G4EML

[ON6XX]

Hi Colin, Thanks for the info. here with the new results. Everything approximate. testing analog on 145 and 430 with the apparently not the best accuracy CN901.

VHF 145Mhz

100mw : 830
250mw : 850
500mw : 860
750mw : 870
1W : 880
5W : 930
10W : 980
25W : 1100
40W : 1500


UHF 435Mhz

100mw : 480
250mw : 540
500mw : 590
750mw : 620
1W : 640
5W : 820
10W : 1020
25W : 1500
40W : 2500

[G4EML]

Thanks, that is a useful set of figures.

As you can see, at the low power end the adjustment is very critical, especially on 2M. That is why it will most likely never be very accurate. I think you will find that is also changes with power supply voltage and temperature, so if you measure again in the future it may be different.


Colin.