JT what - Ah, JT9!

Well,

A while ago I had a play with JT9 - its a cousin of the popular JT65. JT65 was designed for V/UHF comms and JT9 was designed for L/MF. Now JT65 has proved popular on the HF bands generally, and , for example on 20M, you would find JT65 with a dial frequency on USB of 14.076. Now, JT9 is typically found 2KHz above this, so on 20M this would need a dial frequency of 14.078.

The latest and greatest piece of software from the gang that develop the WSJT software, more specifically WSJT-X, have now included a bi-lingual feature! The software can receive both JT65 and JT9 at the same time!

To do this you need a radio capable of a wide RX - 4KHz required here for the full spectrum of both types of transmission. I have completely failed to find  way to do this with my FT-DX-3000, but have managed to get the FT-DX-5000 configured to do this.

I hoped to do this in PKT mode, but the width is fixed at a maximum of 2.4KHz in this mode, but in USB you can set the bandwidth to 4KHz (I struggled to see this full bandwidth in the waterfall until I remembered that I had a 3KHz roofing filter in line - doh!).

So, here is a screen shot from the latest WSJT-X:

including my first JT9 QSO with CT1FBK - thanks Miguel! The JT9 signals are to the right of the blue line at 2500Hz in the smaller window with the JT65 signals to the left.

Now, most (if not all) commercial SSB transceivers include an audio filter in the TX path, this means that the radio cannot generate the tones over the necessary spectrum for both JT65 and JT9 with a single dial frequency. To get round this the software includes CAT interfacing and you run the radio in split mode, using VFO A for RX and VFO B for TX. When you TX in JT9 the dial frequency on the TX VFO is altered and the appropriate tones generated.

Simply genius!

Your going to what?

Well,

You may recall that I bought myself a FT-DX-3000 recently, this is a great radio but I decided I needed to add the narrow roofing filter. I bought said component and prepared to take the radio to bits:

There are a total of 18 screws holding the base of the radio on, once you have all of these removed the inside looks like the photo below. I have drawn a black box round the empty slot for the narrow filter and also added a red arrow which we will discuss further down. Here's the radio without the filter fitted:

and again with the filter in place:

Now, whilst I had the radio in pieces, I thought I would wideband the TX. This is because I want to be able to use the radio on the 5MHz UK allocation including the WSPR frequencies. The full allocation isn't available as-is, so the only option is to perform the full wideband TX anywhere mod.

The picture above with the black box also has the red arrow, underneath the part of the radio with the red arrow pointing looks like this close up:

In the top of the photo you will see that there are 9 numbered points on the board, two of which (6 & 7) are populated with 0 ohm SMT resistors or more simply links.

To wideband the FT-DX-3000, you have to bridge the pads number 5. Here is the radio with the modification complete:

You have to perform a FULL reset for the change to take effect (hold down fast & lock then power on).

Simple, egh?

My antennas got no nose; well no decent SWR anyhow!

Well,

Further to my musings last time about SO2V, I've been making some changes here with a view to getting a second HF general purpose antenna up in the air - the idea being that this can be connected to the second V!

I took down the 30M (10MHz) dipole that I had here and put up a half size G5RV - this was something I had kicking around anyhow and it's fed with 400 Ohm ladder line. It's good and clear and up quite adequately high. I was rather horrified and/or surprised to find that signals on 40M were way stronger on this G5RV than on my 40M/80M dipole - something was not right!

So here's what I did:

• Checked the antenna SWR to find it close to infinite everywhere....
• Replaced the feedline (RG213) between the shack and the ground level under the dipole centre.
• Replaced the feedline (RG58) between the end of the RG213 and the dipole centre.
• Checked the SWR with the analyser at the end of the RG58 feeder and there is a clear SWR curve around 7 MHz ish
• Then checked the SWR at the shack end of the RG213 cable and its 10:1 flat….
• Went for a curry
• Decided to look again at the dipole centre so I dropped the antenna again
• Centre looked OK, so tried to pull the antenna back up and broke the bailing twine in the pulley at the top of the pole at the bottom of the garden
• Gave up completely and went to bed 

Today I've replaced the pole at the bottom of the garden and made an alternative antenna, here is the design I came up with:

The inductors ("L") in the design calculate out at about 80uH.

The first thing I did was to just construct the two 33' legs of the antenna and get them tuned to the RTTY/Digital segment of 40M - that was a doddle. Then I added the coils and the stubs, the calculation was aimed at 3.050MHz and here (using my new fancy analyser thingamabob):

So not bad at all! Here's the plot for 40M now I've added the stubs - clearly there has been some slight de-tuning of the 7MHz part of the antenna, but I can live with it for now and fiddle some more with it later:

The only other thing I have to report was that following my being a good boy at work I have bought myself a gift:

The picture doesn't do the radio justice; it's quite nice looking and has a shiny finish (not the normal Yaesu matt). The good things are that the radio includes a CW decoder, plus in-built decoding for PSK and RTTY - you can also send all three modes without any external equipment.

All in all I think it will be an excellent second radio for me - it has replaced the TS-590 - too early to report fully but early signs are good!

Fun, egh?