Should yaesu ft901dm drift constantly?

Discussion in '"Boat Anchor" & Classic Equipment' started by KG7HVR, Oct 2, 2018.

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  1. KG7HVR

    KG7HVR Ham Member QRZ Page

    Only the my two 901s continue to move around. I really wonder if the problem is somewhere else in the radio
     
  2. KG7HVR

    KG7HVR Ham Member QRZ Page

    If I use the 901 to just check into a net or something it's usually not too bad but if there's any kind of back-and-forth conversation it it moves back n forth
     
  3. N8YX

    N8YX Ham Member QRZ Page

    This is likely heat related...though a poorly regulated VFO DC supply line may cause the condition. Can you monitor the regulated +6V line under extended use conditions and see if it fluctuates...and if so, when?
     
  4. KG7HVR

    KG7HVR Ham Member QRZ Page

    Yes.
     
  5. KG7HVR

    KG7HVR Ham Member QRZ Page

    I recalled testing the voltage and and monitoring it for 10 or 20 minutes and it didn't fluctuate.
    I'll try to get on the radio later today and test it several times over a period of an hour or two
     
  6. KG7HVR

    KG7HVR Ham Member QRZ Page

    I set the radio to 3.7575 about 3pm yesterday its now 10:30am so 14.5 hrs.
    It is at 3.7562 its still moving. For a while at first i think it drifted higher before migrating to this direction
    This one is im the house the temperature inside here is between 65 and 70 degrees consistent. This thing just never stops anyway I didn't plan this I just turned it on and left it on I need to put a meter on the 6 volt Supply
     
  7. N8YX

    N8YX Ham Member QRZ Page

    Tune the radio to one of the Marker frequencies (say, 3.775ish) and turn the Marker on. Listen to the tone over a period of time. Does it change as the frequency display does?
     
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    Why would a marker be at 3.775 ?

    Is that normal for that radio ?
     
  9. N8YX

    N8YX Ham Member QRZ Page

    Every 25 (or 100) KHz; switch-selectable. S601 on the Vox-Marker Unit controls this.
     
    KA9JLM likes this.
  10. KG7HVR

    KG7HVR Ham Member QRZ Page

    Oh yeah i can hear it change pitch with the drift on the displays.
    With the external vfo I turned it on and in less than one minute it drifted 500 Hertz and it was very obvious.
    The internal vfo has been on for a couple of minutes that it is very slowly drifting so far 100 Hertz and you can hear the tone changes.
    The vfo in the radio is a lot better than the external I've seen the external vfl from cold drift as much as three or four kilohertz
     

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