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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. G3YRO

    G3YRO Ham Member QRZ Page

    The 6V line isn't at all critical in terms of the actual Voltage . . . sure, you don't want it to be 5V or 7V, but otherwise doesn't really matter. But if you change it, it will affect the Clarifier zero position, and the Tx/Rx frequency.

    Obviously if it drifts in voltage, that will affect the VFO frequency.

    I suspect that the reason why SOME people may have exprerienced drift in this voltage (and changed the regulator IC) is if their adjustment pot has become sloppy, and has started moving on its own. (bearing in mind that this Board is bolted to the PA compartment, which has a fan attached - that might be causing vibration if the bearings are bad).

    A simple mod I have done to MY FT101E is to replace both the 6V and Transceive skelton pre-sets with small 10-turn cermet pots. These are not only easier to adjust precisely, but should never move on their own. They also solder straight onto the board in place of the original ones.

    You could also replace the Clarifier zero pre-set next to the clarifier Pot . . . but in my rig i have simply replaced it with a fixed resistor. (there is no need for a clarifier off pre-set in later FT101a, as you can simply set the Knob to line up with the zero mark when off)

    But coming back to your drift problem . . . . I suspect one of the capacitors in your VFO circuit has aged badly, and is causing this problem. The trouble is that the ACTUAL caps Yaesu have chosen will usually result in a net zero drift . . . fitting different capacitors could actually make it worse!

    I've never come across this before . . . . normally any ageing in the VFO components causing Drift can be compensated for with the Trimmer (that's why it's there, and worth re-adjusting every 10 years).

    Let me think about this . . .

    By the way Frank, I've decided to write up all this different advice on a proper web page, as there is a lot of not so good advice out there about these rigs. I have various websites, like this one for my car:

    Roger G3YRO
    Last edited: Jul 16, 2018
  2. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Roger, I think the same thing. That one of the components in the VFO compartment itself is no good. Should I just shotgun replace the dogbone caps and the mylar that are connected to that temp cap i.e. C16, C17, and C18? My feeling is that it would be one of those or C19. I think that would be good places to start anyways. I don't think it's something in the VFO PCB itself, I hope not anyways. Looks like it would be very "fun" to try and get that out and replace it. Considering the temp cap trimmer affects adjustment throughout and that there are no dead spots I don't think the trimmer itself is at fault.

    And yes, I recall our 6VDC conversation before and luckily my trimmers on the regulator board (and elsewhere) are pretty tight and I have cleaned them when I first got the rig anyways. It seems to hold 6.32V consistently even over long periods of time so I don't think there's any reason to suspect any kind of voltage drift problems.

    Yes, I hope you get your site up soon. There really is a lot of a bad advice out there on this rig. Not sure why that is, but it would be good if you can get up something and maybe if required I can help you get some pictures available too if you'd like.
  3. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Also, regarding the 6VDC drift problem it could possible be related to aging capacitors and considering that board is right up against the HV cage where a good amount of heat is generated this could cause it. I know you say the caps are reliable, but if the rig has sat for a long time or possibly a CB lid ran it very hard to the point of near self destruction it could've aged the caps on those boards incredibly fast. When I redid the caps I was sure to replace everything with Pansonic 105C rated caps, every board, every time no fooling. I've had good success with Panasonic 105Cs and a lot of old Jap hi-fi gear with Panasonic caps keep on kicking. I'd rather pay the extra few cents per capacitor to know I have something that will last a good long while.
  4. G3YRO

    G3YRO Ham Member QRZ Page

    No, the PSU electrolytic caps wouldn't cause this, as there's a Voltage Regulator. (plus I have never had to replace ANY electrolytics in these Yaesu rigs, despite their age - they clearly used very high quality ones)

    As I said, I'd be rather hesitant to start changing caps in the VFO . . . the ones fitted by Yaesu will have been carefully chosen for their particular drift characteristics . . . you have no way of knowing whether the ones YOU fit will be right . . . so you could make the drift worse.

    At the very least, I would just change one at a time and see if the drift has stopped. When I get time I will suggest the order of the ones I would change, one at a time.

    Roger G3YRO
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    It would be best to adjust the 6 volt supply to 6.0 volts the way the manual says it should be.

    Then adjust the Clarifier Zero.

    6.32V is not even close enough for Government work, Unless you have no voltmeter.

    Good Luck.
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Why do you think that matters?!

    The Manual says lots of things that EITHER aren't at all necessary . . . or are NOT the best way to adjust things !

    I have probably worked on 100 times more FT101s than the guy who wrote the Manual !

    (this is exactly the same as Service & Repair Manuals for cars supplied by the Manufacturers to dealers . . . the way they suggest doing things in the Manual is rearely the best way to do a particular job, as any good mechanic will tell you!)

    Roger G3YRO
  7. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Anything I would replace obviously be same value and of the same type and if it was possible to get one of the same type with a better tolerance I would do so.

    OK, let me know what you come up with and we can give it a try.
  8. HS0ZED

    HS0ZED Ham Member QRZ Page

    I'm always cautious about replacing a part. Unless you know its faulty its hard to tell if you fixed the problem or possibly caused another. VFO caps can be highly relevant to each other, changing them without a clear appreciation of the action of each one could add a whole extra bunch of variables and you would have lost all point of reference. Particularly in the case of those capacitors it's not just value, tolerance and temperature rating but temperature coefficient, rate of change and direction. You may well have a bad component but it has to be better to track down the faulty one or at least have some firm reason why any specific component is going to be changed.

    I've been making some measurements with my own 101e here. First I set some known parameters. I used an SDRplay RSP1 together with the SDRUno software. To rule out any unknown variables I first let it monitor a 10MHz time signal, we get BPM from Beijing here quite strong. SDRUno suggetsed the signal was 20Hz low, I doubt it is, so I tweaked the offset and let it sit for an hour or so. It didn't budge. Carrier on 10Mhz dead and with the carrier set to give a 1kHz audio tone it didn't move a hair. Next up was the 101e with a loop laying on the case top picking up the 9.2MHz signal. From a cold start it went up about 200Hz over 15 minutes then down about 150Hz over the next 30 minutes. Then it started to climb again but I suspect that was heating in the shack. Aircon was off at this time and room temp reaches about 30 degrees C most days mid morning. When I came back and switched the aircon on it went down a 100Hz or so. My own take on the state of the VFO in my radio. It's good enough. I think local temperature variations might have more of an effect than any variability in the vfo itself. I'm happy that the uncertainty of the measurement process is sufficiently good as to indicate any variations are in the radio but I think it's pretty darn good for an almost 50 year old analog rig. Might not be ideal for long term FT8 use but then that really would be a waste of a 101 :)

    Now back to YACKWM2 (Yet another Collins KWM2!) I must measure the drift on a KWM2 vfo and see how that compares.
  9. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, you concur with what I was saying previously.

    The slight drift you are getting on YOUR Ft101 you could probably get rid of by adjusting the Temperature Compensation trimmer.

    However, to be honest, you're actually best not measuring the VFO frequency, but tuning in a stable signal, and noting if the whole rig drifts or not.

    The Temperature Compensation is there not just to compensate for any VFO drift . . . it's there to also compensate for any drift in the two conversion crystal frequencies . . . so that the whole rig's final Tx/Rx frequency remains stable, regardless of any temperature change.

    That is how I have always adjusted the FT101 VFOs.

    (I got Frank to check his VFO frequency drift, to confirm that was the problem on his rig . . . but to get it spot on you adjust the Trimmer so that the overall rig's frequency drift is minimal).

    Roger G3YRO
  10. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Well, this is bizarre... I let it sit for 12 hours. Turned it on about 2 hours ago. Let it sit with heaters OFF for about an hour and it only drifted about 100-125hz. Turned the heaters ON and an hour later now it's only drifted maybe 50hz. This is assuming it was at 1000hz for the tone as monitored by my IC-746PRO. So basically, after an hour no heaters 1100hz, now its more like 1050hz. Really tight now. Not sure what happened. I did have the bottom cover off (of the rig not the VFO), but I just put that back on and will wait another hour and see what happens. I don't think the bottom cover would affect things that much.

    Maybe just resoldering that clarifier wire fixed things? Who knows?

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