FT-101B accessory cable help

Discussion in '"Boat Anchor" & Classic Equipment' started by KI7WQH, May 15, 2018.

ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: L-MFJ
ad: MessiPaoloni-1
ad: Subscribe
ad: Left-2
  1. KI7WQH

    KI7WQH Ham Member QRZ Page


    I restoring a complete FT-101 station from parts acquired from eBay piece by piece (yes, it is a nightmare). My latest issue is trying to get my FV-101B external VFO to work with my home made cable. At first I just matched pin to pin on all 8 pins and this seems to work with the YC-601 digital display. My homemade cable works when connected to the digital display and the frequencies are accurately reflected, however when I instead plug in the external VFO all that happens is the bulb in the unit lights up. When I select the external VFO on the FT-101 all that happens is I lose audio and the internal VFO no longer works. The external VFO seems to not function at all. Does anyone have experience with making these cables? I would love some input on this as I have no idea if it's my cable or my FV-101B unit that is bad.

    Thanks for any help you can give!

    Attached Files:

  2. KE0ZU

    KE0ZU Ham Member QRZ Page

    Get, read, and understand all the documentation. The "restoration" will go much easier.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    Pin 4 should have +6 Volts, Pin 5 is +12V. Pin 1 is ground. Observe view.
    Last edited: May 15, 2018
  4. G3YRO

    G3YRO Ham Member QRZ Page

    Did you use screened cables (miniature coax) for the actual VFO signals?

    Unlike the diagram posted above, you should have a screened cable between Pins 6 AND pins 7 . . . one is used for the output of the Internal VFO to the Counter, the other is used to feed the external VFO to the Transceiver. That could be your problem.

    I would also not recommend connecting pins 7 & 8 together in the plugs . . . run an ordinary wire between Pins 8, but use Pin 7 to connect the shield (outer) of BOTH coax runs.

    Also, note that the VFO signals (both internal or external) are not actually switched . . . merely the POWER to each VFO unit is disconnected by the rig's VFO switch. So your external VFO is powered by the switched regulated supply on Pin 4, via the VFO Switch and the T/R Relay. So next thing to check is if the external VFO board is getting the 6V supply OK. It could be something as simple as the VFO switch needs cleaning - I always use a spray combined Switch Cleaner/Lubricant, turning the switch back and forward.

    Roger G3YRO
    Last edited: May 15, 2018
  5. KA9JLM

    KA9JLM Ham Member QRZ Page


    That diagram came from the Yaesu VFO manual that I have.

    Is it wrong ?
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Well I only have the External Frequency Counter . . . and my cable has two coax runs, one between Pins 6 and another between Pins 7 .

    I'm guessing then that Pin 6 is used to feed the Ext VFO to the rig, and Pin 7 to feed the Frequency Counter.

    Roger G3YRO
  7. KI7WQH

    KI7WQH Ham Member QRZ Page

    Thanks for the replies guys - should the VFO function at all if I'm not using coax? I will definitely remake the cable once I get some coax I just thought it would at least respond without it. I know it's getting some power because the bulb above the dial comes on (even when external VFO is not selected from the FT-101) However the red LED never comes on.
  8. G3YRO

    G3YRO Ham Member QRZ Page

    It MAY work on receive with unscreened cable for the VFO signal . . . but likely to go beserk on transmit.

    But the fact that the LED doesn't light up when you switch to Ext VFO shows that no power is getting to the External Oscillator board.

    Are you sure you have the right pins connected, and not a mirror image on one end? (Some of these Octal plugs are numbered differently)

    Roger G3YRO
    KI7WQH likes this.
  9. KI7WQH

    KI7WQH Ham Member QRZ Page

    You were right! I just rewired the cable and receive is working great now. The digital display gave me a "false positive" by functioning normally so I just figured the cable was good. I really appreciate your help. As soon as that coax comes in I'll remake this cable and then make another so I can patch in the YC-601.

Share This Page