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

    If the calibrator signal is weak, the it's not the antenna relay, as it goes in AFTER the relay. (it should read S9 +20dB on 14.200.

    Roger G3YRO
     
  2. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    OK, good to know. As the calibrator signal is very weak. It's audible but not moving the meter and it's faint. Will try cleaning the other pieces tonight and let you know.
     
  3. G3YRO

    G3YRO Ham Member QRZ Page

    As I said, check the common wire going to the bandswitch from the Rx front end coil hasn't broken.

    Roger G3YRO
     
  4. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Will do, haven't had time to sit down yet today to look at it.
     
  5. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Roger, if you're referring to the big wire soldered to the center part of the bandswitch it is attached. Wiggling it does not change anything. If this is not the right wire can you provide a picture?

    I removed and reinserted NB module a few times. It must be working because without the receiver is completely dead. If I move the NB adjustment trimmer all the way to the right it will make the receiver almost dead. I set it back to where it was. What is interesting is this particular board has had some work done to it before with cut traces and some additions on the back of the PCB for the NB. Not sure if any of this matters. I've never used the NB itself, but looks like flux was left on it and not cleaned up all that well. I can try and clean it off and check to see if this is the problem.

    I didn't clean the band switch itself but it looked OK (I recall cleaning it just for completeness sake back in August) and I rotated through it about 5 full 360 deg rotations and it does not change anything. I tried poking around a little with some chopsticks on the different wires by the bandswitch and nothing.

    I do have a Tektronix scope, so if there's points (with pictures maybe? or some easy to find references via the board layouts in the service manual?) then maybe we can start probing some points and we can narrow it down that way.
     
  6. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Hi everyone,

    I talked to Carol Maher, W4CLM, of the FoxTango website. She sent me two new FETs (one as a spare) and an extra PB-1811 module. I told her everything I went down the list of checking which includes the relays, removing and cleaning then reseating all modules, poking things around with chopsticks, doing visual inspections of the band and mode switches, cleaning the RF ATT, NB, RF Gain, etc. switches and pots, removing the bulb in the back and checking that and cleaning the contacts. She was pretty certain it was either the FET itself or something with the module. Well, she is right with her spare module now the radio works fine. So I will have to look very carefully and compare points on the board to find what is defective. It's not the FETs and as I tried replacing those. And there is only one electrolytic on this module and it was replaced last year with a 105C Panasonic so I don't think it will be that either.

    Thanks for suggestions, will keep you update. But, if someone knows of good comparison points to probe at with an ohmmeter I can do that and report back.
     
  7. G3YRO

    G3YRO Ham Member QRZ Page

    Sorry, been away all weekend.

    Most of the things you previously checked would not affect the strength of the Calibrator, so they were unnecessary.

    I've never seen a fault on the RF Board, so it's pretty unusual . . .

    But just check it doing resistance measurements with a multimeter . . .

    It could be either of the Diodes D1 or D2 . . . . or possibly Q2

    Also check all the resistors around Q1 and Q2 (didn't you say a couple looked fried?)

    Roger G3YRO
     
  8. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Roger, they did not look fried they just had some of the insulation peel off. I did probe at various points where resistor networks are and they all seem to be about within the same ranges of each other. Diode seems OK at least with the diode tester on my DVM. Reads about ~2.5V in one direction and ~0.5 in the other. Is there more than one diode? I only know of the one by the socketed FET.

    My other guess would be something stupid like a solder joint that I will be unable to verify with a visual. I might just try and reflow solder to all the joints and see if it magically works again.

    Can't you use the diode tester on a DVM to test a transistor? Testing it while its plugged in to the rig will be pretty much out of the question since there's little space to pull it off. I don't have long, thin "finger" probes for that. Carol, W4CLM, said she used to sell extender boards for being able to test stuff easier in circuit but she doesn't make them anymore and has no more available.
     
  9. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    Regarding this sidetone adjustment how do you adjust the crystal? It looks like for the resistors you just follow Pin 12 on the PB-1315(Audio Unit) and there's a couple of resistors that leads to that would control it or is that just for the audio level?

    Another thing I've noticed is that the alignment for the CW TX vs RX seems a bit off, about 200-350hz. Now, I did do the zero offset like this:
    " 2) All you need is an inexpensive HF SSB receiver. Pick a band and place your receiver next to the FT-101, and set it to either LSB / USB. Tune your monitor receiver between 8700 and 9200 kHz and listen for the VFO beat tone. Set the receiver fine tuning to give you a tone you find pleasing to your ear. Press the PTT switch and listen to the tone. You will most likely hear a shift. Set the "zero" pot on the regulator board to eliminate the tone difference. You can do this adjustment to get the difference down to about 5 Hz; or whatever your ear can detect. It's simple, and it works. - from W4CLM / K6WWH."

    That method works great and I was pretty close already. I was only off about 10hz or so. I've tested with two rigs into dummy loads near each other and what happens is I'll transmit on say 7.055.0 and with the clarifier off I can see in the waterfall instead of being at 800hz in the center it's more like near 1000-1200hz when transmitting back on the other rig. I basically have to have the clarifier ON for CW work and have it bumped just a tiny nudge to the left to get it closer to 800hz. Otherwise, sometimes you get people with older rigs or wide RX filters and they don't bother to tune close enough to you and you may not hear them.

    I ask about this because, SSB seems fine I've done some tests there even made a few contacts and checked into some nets and everyone says I'm pretty much about on frequency. My guess would be either those resistors for the sidetone oscillator have drifted or the CW crystal perhaps? If it's the crystal to adjust is that resistors as well? How would I do that?
     
  10. G3YRO

    G3YRO Ham Member QRZ Page

    The procedure you describe to align the Rx/Tx frequency is correct (until recently, at home I never had a receiver that covered the VFO frequency, so I just tuned in the Calibrator on the FT101 and on another receiver, so that they were exactly the same pitch (you can beat them together so get closer than 1Hz) . . . then went to transmit and adjusted the Zero pot until I was exactly on frequency (again, if you get slight feedback from the cans you can get it bang on frequency)

    However, a VERY useful mod is to replace the Zero pot with a 10-turn Cermet trimmer . . . the original skeleton ones move slightly with vibration, plus the multi-turn ones are MUCH easier to adjust to be spot on.

    On CW, it's the trimmer capacitor above the CW Osc crystal that decides your transmit offset. (the FT101 uses USB on CW receive0.

    Normal practice is to adjust the offset to be the same as the pitch of the Sidetone oscillator . . . in that way, if you tune someone in and press the key (on receive) so that both tones are the same pitch, you are exactly on their frequency. (again, you can set this using the calibrator signal and another receiver)

    There is no adjustment for the pitch of the Sidetone osc (only the audio level) . . . if you want to change it, you would have to alter the resistors in the Phase-Shift oscillator circuit. (R29, 30 & 31)

    Roger G3YRO
     

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