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

    I have two of these radios and they've both been recapped in the power supply and regulator boards. outside of that nothing else has been touched. they both drift identically. one of them was repaired by a friend who repaired a problem on the IF board. He noted that the frequency display actually drifted as well as the radio.
    I use these radios on 75 meters for rag chew. I constantly have to re-adjust a slight amount so that people will stop complaining that I'm drifting. I would say that it drifts about a 200hz or so. Never stablizing. I have left it on for days before.
    I haven't particularly paid attention to see if it continues to drift if you're not using it. but what I noticed is that when you talk on it it will drift because of the Heat or something like that you'll adjust it and then listen and it will drift again and it's this constant back-and-forth deal. my ft 101 B doesn't do this at all maybe for the first half-hour it will do it if it was just turned on but this radio continues to do this the entire time you use it both of the radios do the same thing. I really like the Ft 901 radios but I can't find an external vfo within reason and I'm so tired of this thing drifting that there must be either a solution or problem... or this is just a characteristic of this radio?
     
    Last edited: Oct 2, 2018
  2. KO6WB

    KO6WB Premium Subscriber QRZ Page

  3. KG7HVR

    KG7HVR Ham Member QRZ Page

    Still sold out.. I had looked at it months back.
    Read about temp comp caps in vfo. Earlier today. I'll have to do more research on that.
     
  4. VK4GAP

    VK4GAP Ham Member QRZ Page

    If i recall correctly , get out a digital multi-meter and keep a eye out on the voltages supplying and around the VFO , form cold/turn on to warmer/longer , check for Voltage drift .

    Paul .
     
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    Did you look in the manual ?

    It sounds like it may meet specification.
     
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    The way they word it, It could drift 200Hz in one hour. (Two 30 minute periods.)

    upload_2018-10-2_12-22-25.png

    How are you making your measurements ?

    Good Luck. Operators that say you are 100 cycles off are nit picking.
     
  7. K8ERV

    K8ERV Ham Member QRZ Page

    I've always wondered what people do with all of those nits?

    TOM K8ERV Montrose Colo
     
    KG7HVR likes this.
  8. KO6WB

    KO6WB Premium Subscriber QRZ Page

    I have one , new in it's package. Never opened. Got it for an old BC-342 receiver upgrade and I never did it.
    Contact me via PM and we'll get things going.

    Hope this helps
    73
    Gary
     
    KG7HVR likes this.
  9. HAMHOCK75

    HAMHOCK75 QRZ Member

    KG7HVR likes this.
  10. K6AFS

    K6AFS Ham Member QRZ Page

    Looking at the thread in the link above, there is a great description by Roger G3YRO on the FT-101 vfo split stator trimmer (TC2) for adjusting temperature drift. What an excellent circuit! I notice Yaesu stopped using it on the FT901.
     
    KG7HVR likes this.

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