DM-1801 Frequency Calibration

[k4gps]

I have a 1801 which I loaded GD77 on and it's working pretty well except it's frequncy. Seems to be 200 htz off on UHF when I check it out on my SDR . I have access to a service monitor if need be but I would like to fine tune it, I have googled but can't see anything except turning the CAL FILE on or off. Are there any instructions on how to fine tune this radio ? I am guessing it can be done with manually finessing the CAL file but I don't want to screw it up too bad. Want to see if there is a instruction sheet somewhere first. With the CAL OFF I am way high, with CAL on just 200 htz off and it works on simplex OK but my BER rate on DMR is up at around 4% sometimes higher and unacceptable.

[VK3KYY]

The OpenGD77 has a Calibration screen under the Extras menu.

There are separate calibration settings for "Reference Osc" for VHF and UHF.

In theory the value for VHF and UHF should be the same, but strangely , often with the calibration that is set at the factor they use a slightly different value for VHF and UHF. However this is probably wrong, and the reason they did that, was that the radio warmed up between testing the VHF and UHF frequencies and thier automatic calibration setup adjusted to correct for minor heating of the radio, but didnt go back and check the VHF calibration after it did the UHF

BTW

The DM-1801 uses an identical calibration table to the GD-77 and RD-5R, so I've moved this topic to General Discussions