frequency counter for ft-101

Discussion in '"Boat Anchor" & Classic Equipment' started by W1UWC, May 18, 2018.

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  1. W1UWC

    W1UWC Ham Member QRZ Page

    Looking for freq counter for my ft-101. Can you hook up a counter to the vfo to get the receive freq. I have a b&k 1803. I see the counter like the yeasu 601 are pricy. Or any one know about any kits to make a counter for the FT-101? Any suggestions? Thanks in advance for any info.
    Dan w1uwc
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    You can hook a counter to the VFO and get the VFO frequency but to get operating frequency you have to work the mixing scheme backwards. IOW, the VFO operates across a range of roughly 8.7 to 9.2 MHz and that's what your counter would measure. That frequency is mixed against heterodyne oscillators for each band of interest so given the het oscillator frequencies you can work out the final operating frequency but you wouldn't measure it directly.

    If you want to display actual operating frequency you need a frequency counter that allows you to program in specific offset frequencies for each band based on the FT-101's mixing scheme.
    N2EY likes this.
  3. G3YRO

    G3YRO Ham Member QRZ Page

    That is not the only problem . . . .

    The actual transmit frequency will vary slightly from band to band . . . and also moves about 3kHz when you cange from USB to LSB, as well as CW. (as you know, you have to adjust the mechanical dial skirt each time against the Calibrator signal)

    So each time you change bands/modes you need to be able to adjust the frequency readout to zero, to line up with the Crystal Calibrator.

    The YC601 achieves that by having a crystal oscillator that mixes with the VFO to give a signal that is fed to the actual counter, such that the readout starts with 0000 or 5000 at the bottom of the band.

    And there is a varicap Trimmer across that crystal osc, on the front panel, so that you can adjust the frequency as described above.

    In addition, there is a bandswitch, so that the counter actually displays the appropriate first digit(s) for each band . . . eg 14. for 20m.

    Most of the above could be replicated in a homebrew unit, and then using an off-the-shelf counter module . . . but it would be quite complicated!

    I managed to pick up a YC601 cheap (£50) about 25 years ago, so just use that! However . . . having accurately adjusted the VFO Temperature Compensation, my rig is so stable that the mixing crystal in the digital display drifts more than the FT101!

    Roger G3YRO
    Last edited: May 18, 2018
  4. HAMHOCK75

    HAMHOCK75 QRZ Member

    There was also an after market counter similar to the YC601 called the Spectronics DD-1. It didn't have the "calibrate" knob but had a "mode" switch on top for selecting "usb" or "lsb" with led's on the front panel to indicate which was selected. Here is an example of one of those.

  5. N2EY

    N2EY Premium Subscriber QRZ Page

    This can be done, but it takes a bit of doing. Just to make it more of a sporting course, the VFO in the FT-101 tunes "backwards" - when the VFO is at the low end of its range, the frequency of the rig is at the high end of the band.

    The YC-601 is expensive today because it was expensive when new, and so not all that many were sold. Note that there are two models - VC-601 and YC-601B.

    W4CLM explains the operation here: YC601 page.htm
  6. N8YX

    N8YX Ham Member QRZ Page

    I have both.

    The B model is more useful in terms of being a true "counter", and it'll read above and below band edges correctly (e.g., 6.980 if you tune below 7Mhz).

    The original is much easier to "preset" for a desired frequency range. It used individual diodes to program the MHz section of the display, whereas the -B uses two DIP diode arrays. Some surgery required for making the unit work on the WARC bands. You'll run into this same hurdle when converting an FT-901 for use on WARC bands as the counter designs are kissing cousins.

    I'm currently running the original model in the lineup at the moment - paired with an analog-display FR-101. Most of the D (digital) models used the guts and readout from a YC-601 as its frequency display, and one of those is present too. They look nice together.
    N2EY likes this.
  7. N2EY

    N2EY Premium Subscriber QRZ Page

    There is another way.....

    In QST for November, 1977, Phil Rand, W1DBM, described "A Versatile Digital Frequency Display". This is a presettable up-down digital frequency counter which can be used with practically any heterodyne HF rig to give a "digital dial". All you have to do is sample the VFO signal, and set the UP/DOWN and PRESET switches properly. Set the switches to UP and 0000, and you have a plain frequency counter.

    For those who want more digits, the design is easily expanded. The displays could be LEDs by some changes in the drivers.

    73 de Jim, N2EY
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    You can buy a cheap frequency counter with adjustable offsets from China for around $15.
    N5DMC likes this.
  9. N2EY

    N2EY Premium Subscriber QRZ Page

    But will it count backwards? (down counter)?

    If so, that's a great solution!
  10. G3YRO

    G3YRO Ham Member QRZ Page

    No it isn't ! You'e not reading my post . . .

    Even if you program the frequency Offset, it will only be correct on ONE band and ONE mode.

    If you change bands, or change from USB to LSB or CW, it will read up to 3kHz wrong !

    Plus you want the display to start at 500 on 160m, 80m and the 10m sections that start at .5 MHz.

    Even most VFO-based rigs rigs with built-in digital frequency displays, you still have to adjust the calibration when you change modes or change bands. (so even that Spectronics unit WON'T read the correct frequency, as it has no Calibrate adjustment for changing bands)

    Given that the original FT101 series was probably the BIGGEST-selling transceiver worldwide of all time, if there was a simple way of doing this, I'm sure someone would have brought out a cheap aftermarket kit !

    Roger G3YRO
    Last edited: May 18, 2018

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