The quest for a simple FST4W tx - A SOLUTION !!!
Rolf & All,
This post has more than one purpose. First I want to offer a solution to Rolf and second I want to offer related solutions to others on this list. Rob knows my intentions and suggested this group might be an excellent place to start. Let me make the offer and then explain very briefly.
Rolf, as one of the very few already transmitting HF FST4W so that we can start to learn more, thank you. As you know from my efforts to encourage Hans at QRP Labs I feel that the QDX can offer an excellent low barrier entry point for FST4W transmit and receive. Now that he has fixed the spreading problem except for the on-board TCXO, performance is really excellent, even on 20m FST4W -300. For low cost a tx/rx station can be set up to spot and be spotted on 20m FST4W in any of the practical modes, certainly -120 and -300 if not in some situations longer ones. With wsprdaemon this is now producing data about the characteristics of the ionosphere and correlation to solar events and more, things we've not been able to directly observe up to now. This does require an external 25 MHz clock which up to now has meant a Bodnar GSPDO or something similar at >2X the cost of the QDX itself. To get around this price impediment and allow a low cost path for more involvement I have designed and had a few "Poor man's Bodnar" References fabricated. These along with a simple modification to the QDX to replace the TCXO with injection of external 25 MHz and the addition of a GPS antenna/antenna-derived signal will get excellent performance from the QDX. I've been transmitting and receiving FST4W on 20m this way for several weeks now. You know this as we already spot one another on 20m -120. The offer is that if you will send me a suitable postage-paid package I will send you one of these references and a cable to go inside the QDX for the modification. My address is good on QRZ.
The second purpose of this post is to extend a similar offer to
others on this list who presently have a QDX and/or the same need
for an external clock. I am doing this as part of a bigger
attempt to investigate ways of providing "Open Source Hardware".
Over recent years I have generated and fabricated various designs
for improving LF-HF receive performance, first in the KiwiSDR and
then more generally. This has taken the form of a hybrid antenna
system that is presently in use at N6GN/K and VY0ERC, very near
the magnetic North Pole. It has included other applications to
further not only LF-HF narrowband study but also to enable similar
studies through 23 cm.
The problem I've run into is that hardware replication/copying
isn't free in the same way as Open Source Software such as
wsprdaemon. Hardware has to be fabricated and someone, somewhere
must provide resources for this. I don't want to go into
business. For me that would be a headache and have me spending my
limited time on things that aren't enjoyable. So I've been trying
to learn how to use the lowest cost paths to hardware fabrication,
initially with JCLPCB in China, and parts selection/design to
produce the lowest cost solutions. The above mentioned Reference
is an example of this process and the reason I have a few of these
to give away. That hardware and the associated code are, like most
engineering projects, never finished and subject to change but it
is working well enough to provide good operation on FST4W through
VHF if not up to 23 cm as well. These are not Bodnar GPSDOs in
performance, the Si5328 synthesizer chip used in the Bodnar Mini
alone costs about as much as all the components in my design ( I
think, I'm still working on parts procurement to go along with the
low cost manufacturing/assembly). They are pretty good and I think
would serve well in many QDX 'good homes'. See the link below for
a little more description or ask if you need still more
Beyond the Reference there are a number of other designs that
might immediately serve this group. For one, I also have a small
quantity of 'proto' 8-way Isolating GPS Distribution boards
available under the same conditions. "You get what you paid for
it" and no guarantees or implicit support, though I'll help as I
can. These boards are particularly useful for
multi-Kiwi/wsprdaemon installations which this group probably has
a concentration. The preamplifiers, juntion, diplexer and 'shack
board' for the hybrid antenna system are also close to being
fabricated in larger volume and hopefully at relatively low cost.
If you think you might be a good match for either the Reference
or the GPS distribution board, particularly if it would allow more
FST4W activity and more data into the databases, I invite you to
join me on Rob's video meeting tomorrow and we can talk. In the
meanwhile you may visit a sort of incomplete 'catalog' of these
and other pieces that are or may soon become available in this
same overall context. Again, these are free, I'm not charging for
them. If you get one and it is useful and you want to contribute
to the next round of 'production' perhaps with your participation
of time/effort even more necessary than funds, we can talk about
that as well.
Please feel free to browse a preliminary, sort of mock-up, list of some of this HERE. Please don't spread this around too much for the moment, I may burn out on it and the whole idea of Open Source Hardware may be silly. I don't know yet.
On 1/10/23 09:32, Rolf Ekstrand wrote:
Hmmm, alligators, hmmm, guess you got the priority right =:~|
To get a fast start just use the RFzero manager: https://rfzero.net/documentation/rfzero-manager/ Then you don't have to fiddle with the Arduino installation. The commands at the RFzero config> prompt are:
wr call k9dzt
wr loc en52wx
wr mode 1
Then you will be on the air with FST4W-300.
www.rudius.net/oz2m :: www.rfzero.net
I appreciate your offer. I'll will bring the RF zero with me and some LP filters and the other parts needed to set it up. I think the set up program is straight forward and should not be any problem, but I have not yet loaded it and connected the RFzero as I have some alligators snapping at my back that needs to be handled otherwise we can't take off next week.
I'll get back to you if I have any questions.
If you want we can arrange a Skype or TeamViewer call and set up your RFzero in 2 minutes. All you need is to enter call and locator and perhaps the FST4W submode. The rest will be taken care of by the default values.
www.rudius.net/oz2m :: www.rfzero.net
In the meantime I have run the QDX 4 ( on 9 V) with the latest program (1.07) on 20m, but it still seems that the spread is way to much to desire. It is much better than my old QDX 3, however I guess it will still need an external reference. I have also run it outside the small enclosure with an additional heat sink, but it did not improve. Thus I guess it is back to the drawing board.
I managed to get my hands on a new RFzero over x-mas and it showed up at my door the other day. I have not yet had time to set it up and I doubt it will happen before we take off for Orange Beach, AL next week, but as usual I will be QRV on at least WSPR . Most certainly I will try FST4W with the QDX if I can't get the RFzero set up and tested before taking off.
For the many in the group who do not follow the QDX on the QRP labs forum I though I should update with some very good news.
Hans Summer, QRPLabs and QDX author has released some new beta code for the QDX which has essentially solved the QDX's problems ! It now does a very good job of reproducing the incoming transmit audio from WST-X. example such that transmitted spectral spreading is essentially zero and the radio can work well on all the FST4W modes, even on 20m. For -300, -900 and -188 sequences some external reference is still needed to take care of PA heating induced drift but the receiver and the transmit now have become a *very* low cost way of getting on FST4W. This certainly bodes well for the hope of increasing FST4W activity, increasing spots and generally making WD even more valuable.
At present, a suitable external clocking GPSDO device like a Bodnarmay be necessary to control TCXO drift but there may be even less expensive solutions possible not too far in the future. While a QDX is not a stand-alone beacon generator, it does require a host running WSJT-X or similar for generation and decoding of FST4W, I think it represents a very good value. It is a complete transmitter & receiver and if you've waited to now to see if there was an easy and inexpensive way to get on FST4W to help provide more and deeper spots on HF, I think the time may have come.
With the new FW, the QDX very accurately follows incoming audio and produces a very acceptable 5W to drive an antenna on a 80,60,40,30 and 20m.
If you haven't already noticed, -300 mode (5 minute sequence) can provide 5-6 dB deeper decodes and many more spots under the right conditions. With the QDX and a Kiwi using GPS-aiding we now have a path to even more spots and better investigation of the ionosphere as more stations can come on with this mode. WD already is able to simultaneously decode all of WSPR2 and FST4W modes.
There's no douibt more to come on this subject but I wanted to be early with good news.
Fort Collins, CO
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