Cat and Vernier Mod for HF-319cplr

The cat was sleeping again on my dresser and I had just finished checking the tuning on my vernier mod. Here she is:

The cat sleeps under the HF-319 with a vernier dial attached next to a Mean Well PSU and assorted cables.


On to the important part, the antenna tuning. Since the HF-319cplr provides a half-turn air variable capacitor internally, I set the vernier dial to operate from about 0.8 to 7.0 on the 0-10 scale. Using my nanoVNA and a careful hand (yes, tuning is still really touchy even with 6:1 reduction), I get the following tuning measurements for the stock HF-319 coax loop.

  • Lower band
    • 5.05: 3.615 M
    • 5.5: 4.030 M
    • 6.35:  5.230 M
  • Upper band
    • 2.15: 5.350
    • 4.45: 7.200
    • 5.65: 10.110
    • 6.3: 14.200
    • 6.6: 18.160

Lots of unused space on the dial, but that's what comes with a multi-band small transmitting loop antenna. Knowing these approximate tuning settings should make getting to fine tuning on the nanoVNA much easier, even if the values shift with not having a brick-and-drywall wall in the near field.

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