FT-101E Intermittent Audio level/S-Meter level

Discussion in '"Boat Anchor" & Classic Equipment' started by KB3GWQ, Jun 26, 2018.

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  1. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Yes, I'm probably getting confused. So, to reiterate:
    1) Go to USB. Turn on 100hz calibrator.
    2) Rotate dial so the tune is at 1000hz.
    3) Adjust preselector for S9+25dB.
    4) Rotate tuning dial to lower the tune and STOP at S9.
    5) Adjust USB variable cap to shift the tune lower to 200hz.

    I know the calibrator is spot on. I was able to align it perfectly last night to WWV and it actually only needed a very slight nudge. It was off by maybe like 3hz.
     
    Last edited: Jul 4, 2018
  2. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    And for S-Meter calibration. Get the tone at 1000hz? Sorry for all these questions, but once we resolve all of this I have plans to compile all this data into some sort of FAQ and see if FoxTango will add it somewhere. The manual assumes that I lived in the 1970s and just know how to set this stuff. Some day this information will be lost.

    I really appreciate all your patience Roger. FT-101 is a fb rig and with your help it will be performing at it's best for many years.
     
  3. G3YRO

    G3YRO Ham Member QRZ Page

    To calibrate the S Meter, yes turn the Calibrator to the 100kHz position, tune in the signal so the tone is around 1kHz on 14.200, peak the Calibrator (making sure you have a Dummy Load connected, or else it will read incorrectly) and set the S Meter pre-set so it reads S9 + 25dB.

    And NO, to adjust SSB Crystal you're slightly wrong:

    1) Go to USB. Turn on 100hz calibrator.
    2) Rotate dial so the tone is about 1000hz.
    3) Adjust preselector for S9+ 10dB.
    4) Rotate tuning dial to lower the tone and STOP at S9.
    5) Adjust USB variable cap to shift the tune to 200hz (it may have been higher or lower than this to start with)
    6) Repeat 4 and 5 in the LSB position, and adjust the LSB Trimmer.
    7) Now see if you can get a 800Hz offset on CW !

    Roger G3YRO
     
  4. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Roger. Did it all and the S-Meter was off by about 25db. The USB was off by about 50-100hz. LSB is off about 50hz too high but I can not get it any tighter.

    With all of this if I test sending to myself and the calibrator for CW is set at 800hz then I am zero-beated on RX dead-on @ 14.200 when transmitting CW from the 746Pro. If I transmit back from the 101e it's still off by about 250-300hz. Adjusting the offset will only make it even wider. 250-300hz is as tight as it will get. So we're basically back where we started with a few small nudges.

    That's why I'm wondering if it's accurate on a real 101e or is it a component problem on the board that is not allowing me to get this tighter. What's the next step?
     
  5. G3YRO

    G3YRO Ham Member QRZ Page

    I'm slightly confused by what you say . . .

    If you tune in the calibrator on CW so that you get an 800Hz tone on 14.200 . . . you would then adjust the outer ring so that it reads 0.

    If you now transmit a carrier on 14.200 from another rig, you should ALSO hear an 800 Hz tone on the FT101 rx . . . is that what you get?

    When you now transmit on CW, how are you measuring your transmit frequency?

    Roger G3YRO
     
  6. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Yes. On 14.200 on CW with Calibrator on I zero beat the Calibrator to the CW tone which is about 800hz.

    If I transmit on 14.200 on CW with another rig I receive it properly zero-beated at 800hz.

    If I transmit on 14.200 on CW with the 101E instead of transmitting at 14.200 it's more like 14.197-14.198. If I adjust the CW TX offset on the rig that is the best I can do. Any further adjustment will make it veer farther away like say 14.195, etc. I just can not get it tighter.

    I measure the transmit frequency by looking at in the waterfall. It's not zero beated you can see the tick marks in Speclab and it's pretty accurate. I've used it so far to dial all this in properly.

    If it helps, I can take pictures of speclab comparing to what I see on the FT101 and the 746PRO.
     
  7. G3YRO

    G3YRO Ham Member QRZ Page

    OK . . . although I presume you mean 200 Hz off frequency on CW, not 2kHz . . . so around 14.199.8

    Even so, I have never known the crystal to move that far off the desired frequency.

    As you want to move it higher in frequency, you can't add a padder, you need to reduce the capacitance in the circuit. Try unsoldering the trimmer completely, and see where the frequency ends up.

    By the way, you see the small capacitor connected from the collector of each osc transistor to ground? You need to make sure this is bent over so that it is actually touching the case of the transistor, as this tiny amount of coupling provides the feedback for this oscillator circuit to work properly. (You might check this first and see if it has moved the frequency at all.)

    Roger G3YRO
     
  8. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Yes. I mean 200-400hz off frequency. I will check the small caps. It's possible either I bent them to stand up or someone else did. But, yes I can try unsoldering the trimmer on Friday and see.

    What is the range of the trimmer anyways? The parts listing says it's 20pF but I don't know what the low end would be. I guess if it goes above where I want it to be with it removed maybe we can cheat it with a different trimmer. I'd be OK with that.

    Apparently this crystal and trimmer also affect AM but I'd have to try it with headphones on the other rig and see how far off I am and I'm not entirely sure if 200-400hz offset really matters for such a wide mode like AM? I've unfortunately never had the pleasure. There's some AM guys on 160M I hear sometimes but I don't have an amp and I'm just using a 127ft endfed up about 25ft so probably won't do so well I'd imagine unless it was very local.

    I don't know how to test a crystal's frequency. But, I have seen something somewhere online where someone has mentioned these crystals on the 101e need taken apart and cleaned inside sometimes otherwise they can be fairly off frequency. But, if that's true I'd figure you'd say something about it by now and I have no idea how to take them apart or if it's dangerous to do so... so best not chance it unless I could source another crystal easily.
     
  9. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Roger, here are some pictures of the board. Are you talking about the three transistors below the crystals that have the "Y" lettering on top? If yes, are you referring to the very tiny red caps NOT the ceramic discs? If so, it looks like the one for LSB is actually leaning on it. The one for USB the transistor is too high for it be able to lean on it and for CW it is not leaning on it.

    The one picture you can see how high they are on the board.

    On the back there appears to be factory modifications to this board. Please verify if they are. The only modifications done by me was changing the one electrolytic with a Pansonic 100uf 16V 105C rated cap.
     

    Attached Files:

  10. HAMHOCK75

    HAMHOCK75 QRZ Member

    Looks like there is the suggestion that the 3,179.3 KHz crystal is off frequency. Normally quartz crystals do not move anywhere near several hundred hertz from aging effects at such a low frequency. Just an idea but it is not all that well known that quartz crystals have spurious modes on the high side of the fundamental resonance as shown in the figure below,

    https://vectronblog.files.wordpress.com/2017/01/spury.png?w=1024

    If the loop gain of the oscillator active element is sufficiently high or if the spurious resonance is unusually strong, it can break into oscillation at one of the spurious modes instead of the desired mode. The solution is to lower the gain until only the desired resonance can provide sufficient feedback to oscillate. Sometimes rotating the trimmer cap through its range can cause it to pop into the desired mode or simply lowering the power supply voltage can lower the gain enough.

    P.S. A properly working FT101 is not going to be anywhere near as far off as your measurements.
     

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