Sunday, October 14, 2012

JT65-HF - A digital mode for those with lots of time but not much to say

jt65-hf screen
On occasion I've made contact with someone with whom I feel an immediate affinity. I can easily talk for 20 or 30 minutes with someone like that. But when I want to rack up contacts for DXCC or WPX awards I just want to cut to the chase. For these times I find JT65-HF to be the perfect mode.

JT65-HF is a variant of a mode created by Joe Taylor (K1JT). Originally devised for EME, it's now been adapted for weak signal HF work by Joe Large (W6CQZ). It's distinctive chirpy tones sound like Olivia in slow motion.

Common frequencies for JT65-HF are (USB):
  • 80 m - 3576 mHz
  • 40 m - 7039 mHz
  • 30 m - 10139 mHz
  • 20 m - 14076 mHz
  • 17 m - 18102 mHz
  • 15 m - 21076 mHz
  • 12 m - 24917 mHz
  • 10 m - 28076 mHz
The software package of choice is JT65-HF, and the latest version is available here ( Be sure to sign up for email notification when new versions are released. I use Ham Radio Deluxe 5.5 for rig control and logging, but other programs are available.

Installation and set up is fast and simple. Timing is critical in this mode so before each session always synchronize your computer clock. Set your power output to 5 or 10 watts. More than this is seldom necessary because of the extreme sensitivity of the software. In addition, be aware that JT65-HF is a 100% key down transmission for a full 50-seconds. High power could easily damage your rig!

Each exchange begins on either the even or odd minute, i.e., you transmit on the even minute and listen on the odd, or vice versa. For example, I might choose to listen at 13:02 and transmit at 13:03. Each transmit or listening phase lasts for 50 seconds with the remaining 10 seconds used as an idle period.

Here's how a typical session progresses:
  • 10:00 TX CQ KB3IHX FN10             I call CQ for 50 seconds, adding my grid
  • 10:01 RX KB3IHX KI7RM CN85     The DX station responds with his grid
  • 10:02 TX KI7RM KB3IHX -13          I respond with his signal report
  • 10:03 RX KB3IHX KI7RM -15         The DX station responds with my signal report
  • 10:04 TX KI7RM KB3IHX RRR       I send RRR (all received)
  • 10:05 RX KB3IHX KI7RM 73          The DX station sends 73
  • 10:06 TX KI7RM KB3IHX 73           I sign off with 73
During the final round you have the option of sending a custom message, perhaps including info about the contact. Examples include 5W DPLE 73, LOTW KB3IHX, or TU KB3IHX 73.

JT65-HF color codes contacts for your convenience: green for stations calling CQ, red for transmissions directed to you, and gray for all other ongoing contacts. Moreover, each response can be created by simply double-clicking the other station's response. It's incredibly easy.

That's it. Seven minutes from start to finish, although I have seen contacts that go straight to 73 after exchanging signal reports. JT65-HF users tend to confirm contacts via LoTW so building credit for ARRL awards is relatively painless.

Check it out. I hope to see you on the waterfall.
- Steve KB3IHX

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