Tag Archives: JT-65

Exploring a New Digitial Mode: FT8

Joe Taylor is testing a new digital mode called FT8. The development version of WSJT-X software now supports this mode. FT8 ( Franke-Taylor design, 8-FSK modulation) works similar to the more familiar JT-65 and JT-9 modes except the T/R cycle completes in just 15 seconds thus greatly reducing the time to complete a QSO. The bandwidth of the signal is 47 Hz and the decoding threshold is -20dB.

ft8

I downloaded the development version this morning and tried FT8 on 40m. There were just a few signals but I did close my first QSO. Pskreporter showed my signals was also being received in Australia this morning. Some things to note: Logging may not work and I understand that LoTW does not recognize FT8 as of yet. Also, the software autoexecutes the T/R sequence once the QSO starts. You have less than 2 seconds to select the station to respond too!

 

Working 40m and 17m this Weekend

I reconfigured what has become my main antenna, the 40m 1/4 wave vertical. This is still a temporary installation but I am growing increasingly happy with the results I am getting. I frankly can’t remember the last time I used the horizontal end fed. I have had to roll up the radials on occasion to mow the yard and have not yet deployed my permanent radials. Currently I am using the 30 foot travel mast from SOTAbeams to support the vertical wire and have four 27 foot radials deployed. I am using my homebrew 1:1 current balun at the feedpoint and running to the shack with 50 ft of RG-8X.

If I get the chance I’ll start operating around 6:30 am local time on 40m JT-65. I can usually snag several contacts in Japan with the occasional contact into Australia, Indonesia or the Philippines. The action is over by about 7:30am local time as the band closes quickly after sunrise.

Saturday afternoon, I was checking the bands and came across a strong VK station on 17m SSB. We exchanged signals reports in the 54 to 55 range. I moved over to JT-65 and found that there was DX activity including another VK contact. Today Sunday I am finding about the same conditions, great 40m propagation to the far east in the early morning and some light DX into Europe & South America on 17m in the late afternoon.

 

Transmit Power Using JT-65

I came a cross a very helpful web page in determining the amount of power needed for JT-65. It is called dbCalc and allows you to enter your transmit power and signal report and then calculates what your report would have been with other transmit power levels. I tried this out today on 40m JT-65, lowered my power in half and still made several DX contacts to Japan and Argentina.  You can easily measure how your signal is doing at a given power by sending a CQ and then checking the Pskreporter reports. Feed these into dbCalc and you can optimize your power settings for given band conditions. I suspect that in most cases operators are using a lot more power than necessary to make JT-65 contacts which makes it harder for weaker signals to get through.

40m QSO’s with 1/4 Wave Vertical

Most of this week was sent collecting WSPR data on the 40m 1/4 wave vertical. The vertical is holding up better to the breezy days after placing some duct tape on the joints of the travel mast. The vertical radiator is a 32 foot length of insulated #14 speaker wire. There are only four 27 foot ground radials deployed at this time. There is a 1:1 current balun at the feed point and about 50 feet of coax to the shack after that. Here is the SWR plot:

swr

SWR is under 1.5:1 across the whole band with a resonant point 7.125 MHz. This antenna has been a solid performer on 40m without a tuner. I am noticing that the band starts opening up to DX about an hour before dusk. Last night I made several SSB contacts with Europe after 10pm local time.

Switching to 40m JT-65 at that time was very interesting as well  as the propagation conditions can be somewhat visualized with pskreporter. I really tested the JTDX software last night and have gotten the hang of the user interface which is subtly different from WSJT-X.  I set the IC-7100 with AGC-off and the bandwidth filter set to 3.6 kHz. Rather than search and pounce, I would look for a quiet spot at the extremes of the band and call CQ DX. This strategy worked well with many European stations answering. Over time, I can see my signals fading on the pskreporter map as eastern Europe’s morning progresses. As dawn approaches in Western Europe, stations start coming online and start to see my signal. At the same time, the opposite terminator starts approaching New Zealand and Australia and my signals starts picking up there as well. I knocked off at about midnight local time and picked up at about 7am and repeated. This time JA stations were answering my CQ and I was running a JT-65 “pile-up” with several JA stations calling at the end of a QSO.

Very pleased with the antenna performance on this band. 20m is acceptable through a tuner but the WSPR data indicates some degradation in performance over a resonant vertical or even the end fed antenna.

Operating this Weekend with a 1/4 Wave Vertical

The winds have died down a bit here at the QTH and the travel mast has been up about a week now. The duct tape on the joints may have something to do with it. On 40m, the antenna is a winner. Made contacts on SSB to Europe in late afternoon early evening on Saturday. Making JT-65 contacts into Japan is like shooting fish in a barrel on early mornings. On 20m, I run the antenna through the tuner and also made some DX into Europe and the South Pacific. I switched between the vertical and the horizontal DXtreme end fed antenna and found that the vertical can definitely hear signals that the horizontal cannot. Propagation conditions seems to be shifting these past couple of weeks. 40m is solid into Asia early morning and Europe in the early evening. 20m has been weak in the morning but picks up in the late afternoon. 17m has been really hurting lately with some small windows opening up from time to time. All in all a good weekend of radio activity.

Hints on setting up Receive on WSJT-X and JTDX

I spent some time reading the manuals for WSJT-X & JTDX to ensure that I was optimizing recieve. This seems to have improved after making the following changes:

  1. Make sure the PC is set for 16-bit 48,000 Hz sound card sampling.
  2. Turn off AGC
  3. Properly set microphone level. This is a two step process. In my case, I dropped the microphone level in Windows to 1%. Then using the Connectors–>ACC/USB AF Level control on the rig, dropped the level until I could get to 30dB receive with the slider at mid-scale. In my case the AF level was set to 10%.

These changes have helped with receiving weak signals. JTDX in particular typically decodes 15 to twenty stations when the band is busy.

Trying JTDX Software for JT-65

I installed JTDX software and have been trying it out on JT modes and WSPR. The decoder is quite superior to WSJT-X in decoding JT-65 in crowded bands. So many stations pop out of the waterfall with this software. I have not noted any advantage in WSPR decoding. Will continue to play with this over the next few days even though I am finding it harder to close a contact with JTDX. Not sure if it is how I am operating or the software yet.

Update 5/8/17: It was definitely not the software’s fault…Looks like a combination of crowded band conditions and propagation were at fault for my initial difficulty making contacts. I have since had better luck on both JT-65 and JT-9.

Update on the 40m 1/4 Wave Vertical

Ran WSPR last night on 40m with the 1/4 wave antenna. Here is the Map as of this morning:

2017-04-13_7-22-51

Started running some JT-65 this morning and while difficult to run pile ups, I am getting QSO’s with JA by calling CQ. On my third one since starting this morning:

2017-04-13_7-24-45

Overall I am very pleased with the performance of this antenna. I’ll be doing some tests on 15m as well although the band has been quiet.

40m JT-65 and the Change to Daylight Savings Time

Early morning hours favor The Western Pacific and Asia on 40m lately. This has been confirmed using WSPR data on the 30 foot end fed vertical. Day light savings time means it stays dark longer in the early morning here at the QTH. I tried 40m JT-65 and it was very active with stations showing up in Japan, Australia, Malaysia, Philippines and China. I did make one contact with a station in the Philippines which was a first for me. The band started dying out about 9am. This looks a great opportunity to work Asia DX even when band conditions are slow (SFI:70 SSN:0). I’ll hopefully try again tomorrow.

Update: 17m is open to Europe in the mid to late morning hours. It is 11am local time here and there is still a lot of activity on JT-65.

17m Is Alive and Well

Noticed that 17m has been open in the morning and early afternoon into Europe and Central & South America. I made some SSB contacts as well as a bunch of JT-65. So now I am operating a bit more as I recover from the surgery. Can’t really work on my antennas yet although I do have plans for installing the S9V31 soon. I will be laying out at least 16 radials and will use the LDG RT-100 remote tuner I just acquired used at the base of the antenna. Hopefully the doc will clear me to do some light work next week about the time the tuner arrives.