Yaesu FT-107 Memory Shift Issue

Discussion in 'Radio Circuits, Repair & Performance' started by WB2QLL, Jul 31, 2020.

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  1. WB2QLL

    WB2QLL Ham Member QRZ Page

    Just this week got an FT-107M, this is the #6 run with WARC and DMS. The DMS memory store and recall works as it should, as does the memory fine. However, when the memory shift button is depressed, the rig starts tuning lower in frequency step by step, and turning the M SFT knob has no effect whatsoever.

    As the manual states, every few steps as it tunes down there's a brief chirp as the DMS relocks, leading me to believe the DMS is working but something is tying its input high or low to cause it to change frequency. Again, only when M SFT is depressed.

    I have the manual in both physical and electronic form and have tried to find the M SFT control, but I can't find it on the diagram. The photo-interrupter control assembly itself looks very complex.

    I appreciate the help.

    Pete
    WB2QLL
     
  2. KE0LPO

    KE0LPO Ham Member QRZ Page

    Hello Pete, Is this your first Ft 107 ? If so the memory circuit is something that has been a problem on this radio. It's somewhat difficult to really understand if your (not you) using it correctly or not. Thats how I found it to be.Its A nice feature . I guess for some. I'd rather have full coverage and until I got this radio the only memory in a Radio that served me well was my presets for car stereo . Otherwise its a great radio. I would not sell mine. . So I just dont use this feature. I'm sorry I don't have any fix's for your Ft 107 . These days the radio considered a rare find especially if it works. Good luck. There's a few of us that have a 107 . Information on this rig other than the service and parts manual is hard to come by.
     
  3. WB2QLL

    WB2QLL Ham Member QRZ Page

    Hi and thanks for your note, even if you don't have a fix, apparently as you say info and expertise on this rig are scarce. However it's held in high regard and I've been interested in one for years and this one came up at a good price and in great shape. It's my first one, yes, and it performs very well, both transmit and receive audio especially good. It had only two problems, the aforementioned and a bad display, which can be fixed by a new chip from a guy in Japan, we just have to wait 'til postal service is resumed. It turns out what I thought was a memory issue wasn't the memory but the up/down board behind the meter. Seems the same circuit that causes the rig to scan from the mic buttons also adjusts the memory shift in pretty much the same way. So it was a bad chip on that board. I never use the memory scan, in fact I never connect a mic to my rigs so I sacrificed that function and I just bypassed the chip in question and it's working perfectly now. The memory is nice because the radio drifts enough from a cold start so people would notice - with the memory set it doesn't so it's as stable as any synthesized rig. 73.
     

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