Yaesu 101 zd Processor problem.

Discussion in 'Radio Circuits, Repair & Performance' started by LW1DSM, Apr 20, 2021.

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  1. LW1DSM

    LW1DSM Ham Member QRZ Page

    Good evening, I have a curious problem on my 101 ZD Mark II and it is the following: The ALC and the processor are perfect on all bands except 40 meters.
    The power output is perfect but the processor does not work by lowering the power when it is activated. The ALC barely marks.
    Thanks in advance.
     
  2. KL7SG

    KL7SG Platinum Subscriber Platinum Subscriber QRZ Page

    Can you get the ALC to increase by increasing the drive?
     
  3. G3YRO

    G3YRO Ham Member QRZ Page

    Everything is the same as far as the Speech Processor is concerned on 40m as every other band . . . so the fault can't be in the Speech Processor.

    I've only ever worked on a few of the FT101Z rigs (as I hate them compared to the original FT101 series) . . . but they always seem very short of Mic Gain and also RF Drive !

    Maybe you just need to re-align the 40m RF circuits . . . then you may find it's OK on 40m too.

    Roger G3YRO
     
    LW1DSM, KL7SG and N8YX like this.
  4. N8YX

    N8YX Ham Member QRZ Page

    I'd go with Roger's suggestion, being familiar with the architecture used in the 101ZD/90x series rigs.
     
    LW1DSM likes this.
  5. KL7SG

    KL7SG Platinum Subscriber Platinum Subscriber QRZ Page

    I also agree with Roger. Advancing the drive, if possible, might indicate that an alignment on 40 meters is the issue
     
    LW1DSM likes this.
  6. LW1DSM

    LW1DSM Ham Member QRZ Page

    I understand, but if the premix and the rest were misaligned, when the processor is deactivated, wouldn't there also be a low signal?
    Thanks !
     
  7. G3YRO

    G3YRO Ham Member QRZ Page

    Yes . . . but that's the whole point . . . the fault is NOT in the Speech Processor, but in the RF Circuit alignment on 40m.

    Roger G3YRO
     
  8. LW1DSM

    LW1DSM Ham Member QRZ Page

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    Here I upload images of the oscilloscope. They are from the 80, 40 and 20 meter bands. Clearly in 40 meters there is a volt less than in the others. Curiously, the power output is identical in all three. This is the tune position. In LSB the amplitude is almost the same. However, putting the processor in 40 meters lowers it to 1.5 volts while in the other 2 it holds just over 2.2 volts. My theory is that having less carrier voltage generates less ALC voltage that barely moves the needle. What I still don't understand is that without the processor It transmits perfectly. Except if I put the meter in the ALC position there is almost no reading despite emitting about 130 watts.
     
  9. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, but if the Het Osc, Mixer and Driver circuits were out of alignment on 40m, that is what you would expect !

    Have you actually peaked those Circuits on 40m yet?

    Roger G3YRO
     

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