Hello Hans,
Many thanks for the in depth summary. I have started building my U2 kit but maybe a week or so before testing etc.
Thank you for producing a remarkable kit and look forward to experimenting.
73`s
Mark Parker
toggle quoted message
Show quoted text
--- In QRPLabs@..., Hans Summers <hans.summers@...> wrote:
All
My email box is full of millions of emails and so I thought, to clarify all
my and your thinking, one big post should list it all out. Summarise where
we are with it all. If I am missing anything, please let me know.
*Enhancement requests: *firstly, there are a number of new requests (other
than the GPS and 10m issues, of which more later). I'll attempt to put as
many as I can in the v2.02 firmware version. These are as follows:
1) Support for the WSPR-15 mode (useful for LF WSPR)
2) Adding 1 digit to the GPS Baud setting, so the kit can be used with
115kbps (also requested for an Ultimate1 v1.09 enhancement)
3) Allowing the / character in messages for FSKCW, QRSS, DFCW, CW modes
4) Removing the 42.5MHz (approx) upper frequency limit
5) Fix a couple of occasional cosmetic bugs appearing in the Time-setting
menu item
6) Move the Time setting to the front of the menu items, as it is used more
often than any others when using the WSPR mode and everything is already
set up (e.g. for correcting the time, when no GPS is being used).
*New shop items requests:* I have had requests to add the following items
to the shop:
1) Selling BS170 transistors separately to the main kit
2) Sell the 4-pin headers and sockets separately to the main kit
3) Make available LF band modules for 475kHz and 135kHz
*10m etc issue:* The summary of this issue is that it appears that there
may be an arithmetic precision issue in the code for setting the DDS
frequency word, which becomes apparent when the amount of shift is small in
relation to the output frequency. So I need to change that part of the code
which deals with calculating the DDS frequency word. Although, it remains
considerably confusing because some people appear to have had some 10m WSPR
spots. Perhaps they were lucky to choose frequencies which happened to work.
*GPS issue:* There appears to be an issue with some GPS modules which
worked in U1 but not U2. There have been some reports of people using GPS
with no trouble, with Ultimate2. My current theory is that the short pulse
width from some GPS modules is interfering with, or being interfered by,
the incoming serial data stream. So I need to look at the differences
between how I did the GPS work in U1 and U2.
*Other comments:*
1) People have remarked on the frequency switching transients when the DDS
frequency changes. I think this is a minor thing which if all else was
well, should not interfere with kit operation or WSPR decode etc. However,
I checked in this area of the code and I did actually find that I think the
frequency is being briefly set to zero before the new frequency is set, and
that this might be making the short frequency glitch longer than necessary.
So in v2.02 I will attempt to tidy that up.
2) Regarding the blue potentiometer on the DDS module. When the modules
arrive from the manufacturer, it appears that the blue potentiometers are
not set up - that manifests itself as no output squarewave from the
comparator. Before packing the kits, I individually tested every single one
of the 200 DDS modules. 29 were discarded as their stability was found to
be unsuitable. The rest of them, the potentiometer was adjusted for best
output on 30m. So I thought that it should not need further adjustment by
kit builders. However, it is possible that the setting on 10m might be more
critical, or different, from the optimum setting on 30m - as some
constructors have found out and advised.
3) Someone mentioned that the maximum output frequency of the comparator is
only 1MHz. However I don't think that this is correct. The specification of
the DDS module from the manufacturer sometimes says that the squarewave
output is valid up to 1MHz. But the DDS module output is straight from the
comparator output pin of the AD9850 DDS chip and I don't see anything in
the AD9850 datasheet about any upper frequency limitation.
4) Feedback on the question of whether to reverse the BS170 transistors in
the new PCB, or reverse the silk screen, or leave as is - was rather
(surprisingly) mixed. So I still have to consider that one.
5) I had some delay with ordering all the components, because PayPal rather
unreasonably decided they should block my account to make sure I'm not a
money launderer. That's all resolved now so I can continue with ordering
the remaining components for the next set of 200 kits.
I think that's about it. Let me know if I have missed anything out.
73 Hans G0UPL
