Re: Morse Code Tutor pcb...
Gary, I'd like to try one of your boards, if you have any left.
Let me know how to proceed.
On 5/13/2025 9:17 AM, Gary W9TD via
groups.io wrote:
I have a few W8BH Morse Tutor boards available for shipping
costs+ (Had to order 5, used one)
Gary
W9TD
--
73
Bob W3RDL
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Re: Morse Code Tutor pcb...
Hi Gary,
I'm game for one (maybe two) board(s). Contact me off-list and maybe we can help each other out...
Thanks! 73, Vern N7GTB (at yahoo)
On Tuesday, May 13, 2025 at 06:17:58 AM PDT, Gary W9TD via groups.io <w9td@...> wrote:
I have a few W8BH Morse Tutor boards available for shipping costs+ (Had to order 5, used one)
Gary
W9TD
|
Re: Morse Code Tutor pcb...
I have a few W8BH Morse Tutor boards available for shipping costs+ (Had to order 5, used one)
Gary
W9TD
|
Hi Bob and all
By way of introduction, I'm a local friend of Bob's, WA7EXH since 1965, and a reader of this group.
Bob, since I last talked to you about this, it's occurred to me that most of my instrumentation projects using 24-bit ADCs? have used point-of-load regulators that exclusively supply the converter application. I've chosen regulators for lowest noise and highest input rejection. I think that this, in addition to the capacitor and inductor installations, has been beneficial to data quality.
There are now regulators that have quite low noise density. A few that are pretty inexpensive are the LP2992, TL1963, TPS7A20. Analog Devices has a few regulators that are also very good: Their LT3046 is a leader in low-noise, high psrr linear regulators, and would be my first choice today. It has good input and output voltage range, not the cheapest, and a DFN package that gets
me into microscope-aided soldering.
?
Mike
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Re: New SI5340-based RF Board in development
Hi Phil-
?
I don't know if there is a performance difference between QSE2DC and the V12 circuit.? There is insufficient data available for comparison.
Yes, carrier nulling is a software task which has been available in T41EEE for quite a while.
?
With regards to the design using differential circuits, this was an attempt to gain all of the benefits of a symmetrical circuit, and
in particular noise immunity.? The T41, in its 3D printed plastic case, is lacking for shielding and grounding.? Now the problem remains
with the Audio Adapter, which has single-ended outputs.? What I've got now is working well enough to continue development.?
In the future, I would like to get a fully differential signal chain in both transmit and receive signal paths.
?
Another goal was squeezing the maximum potential performance out of the 3253 multiplexer.? This device is not specifically intended for
this application; it has been pressed into service as a modulator and demodulator.
?
There is more information on differential and instrumentation amplifiers in the references in the README for the QSE2DC:
?
--
73 Greg KF5N
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Re: New SI5340-based RF Board in development
Hi Greg
?
Is there any difference in performance of QSE2DC and the V12 circuit other than the nulling capacity? Nulling is a software task?
I notice your use of the differential "op amps" for the filters, is that a performance thing?
?
Regards
Phil VK2KKZ
?
On Tue, May 13, 2025 at 09:41 AM, Greg KF5N wrote:
Interesting points!? What I have observed with the 3253 is that degradation is noticeable at 10M.? Still good enough though.? It looks worse at 6M
What I am referring to is the 3253 in the role as a quadrature modulator.? Spurs start to creep up with increasing frequency.? Also carrier rejection
gets worse and worse.? My QSE2DC design has the capability to null the carrier, which mitigates this problem.? But I think this system will run out of
gas before it gets to 2M.? I would guess that performance as a demodulator is also falling off versus frequency.
?
Early in my experiments with the T41, I built a Gilbert cell based modulator using a very old part.? The MC1496.? This is one of the oldest semiconductor
devices still in production.? It worked, but it was already running out of gas at 10M.? I? haven't found a reasonable replacement for the MC1496 yet.
A basic Gilbert cell using modern devices at reasonable cost is what I am looking for.
?
--
73 Greg KF5N
?
?
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Re: New SI5340-based RF Board in development
Hi John
?
Looking forward to your performance results...
?
I haven't yet built an RF board, been stuck on toroids and other things, so would consider your RF board.
?
Regards
Phil VK2KKZ
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Re: Morse Code Tutor pcb...
PCBWay was still offering the Global Express a
couple weeks ago when I placed an order for something else.?
JLCPCB had just stopped it that day. They told me it was because
their Global Express carrier had stopped delivering to USA.
Thank you.
Jim Pruitt
WA7DUY
On 5/12/2025 9:16 PM, jerry-KF6VB via
groups.io wrote:
toggle quoted message
Show quoted text
On 2025-05-12
20:36, John? P via groups.io wrote:
I checked the JLCPCB price a month or so
ago. $4 for 5 boards up from
$2. Not a big deal.
*** That's not a big deal.? The big deal is that their "Global
Standard Line"
$1.50 shipping went away, replaced by $22 DHL shipping.
???????????? - Jerry, KF6VB
--
Jim Pruitt
WA7DUY
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Re: Morse Code Tutor pcb...
Ive always used DHL
--
John P.
WA2FZW
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Re: Morse Code Tutor pcb...
On 2025-05-12 20:36, John P via groups.io wrote: I checked the JLCPCB price a month or so ago. $4 for 5 boards up from
$2. Not a big deal. *** That's not a big deal. The big deal is that their "Global Standard Line" $1.50 shipping went away, replaced by $22 DHL shipping. - Jerry, KF6VB
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Re: Morse Code Tutor pcb...
I checked the JLCPCB price a month or so ago. $4 for 5 boards up from $2. Not a big deal.?
--
John P.
WA2FZW
|
Re: Morse Code Tutor pcb...
I just asked my search engine to list US-based PCB manufacturers. The list contains 484 names. However, none comes close to the prices offered in China (e.g., PCBWay, SeeedStudio Fusion, etc). They may still have the best prices.
Jack, W8TEE
On Monday, May 12, 2025 at 05:08:59 PM EDT, Vern VanZ via groups.io <n7gtb@...> wrote:
Thanks Jack, Doug and Terrance!
Assuming I decide to pursue having a PCB made, what are the current challenges (if any) using the available board manufacturers? Are they still mostly in Asia, and how have the tariffs affected getting small quantities made?
On Monday, May 12, 2025 at 12:17:30 PM PDT, Terrance Robertson, KN6ZDE via groups.io <tmrob4@...> wrote:
Bruce has a groups.io for the Morse Code Tutor.? It has a link to his that seems to have all of the needed files.
-- Jack, W8TEE
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Re: New SI5340-based RF Board in development
Interesting points!? What I have observed with the 3253 is that degradation is noticeable at 10M.? Still good enough though.? It looks worse at 6M
What I am referring to is the 3253 in the role as a quadrature modulator.? Spurs start to creep up with increasing frequency.? Also carrier rejection
gets worse and worse.? My QSE2DC design has the capability to null the carrier, which mitigates this problem.? But I think this system will run out of
gas before it gets to 2M.? I would guess that performance as a demodulator is also falling off versus frequency.
?
Early in my experiments with the T41, I built a Gilbert cell based modulator using a very old part.? The MC1496.? This is one of the oldest semiconductor
devices still in production.? It worked, but it was already running out of gas at 10M.? I? haven't found a reasonable replacement for the MC1496 yet.
A basic Gilbert cell using modern devices at reasonable cost is what I am looking for.
?
--
73 Greg KF5N
|
Re: Morse Code Tutor pcb...
On Mon, May 12, 2025 at 05:14 PM, Terrance Robertson, KN6ZDE wrote:
I didn't build the Morse Code Tutor, but I did build the CW Messenger from chapter 10.? I built it on a protofboard.?
?
Yup, I built the MCT on a solderless breadboard.? My plan was to make a pcb.? Full disclosure, something shiny distracted me and...
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Re: Morse Code Tutor pcb...
I didn't build the Morse Code Tutor, but I did build the CW Messenger from chapter 10.? I built it on a protofboard.?
?
?
?
I'm sure the Morse Code Tutor build would be similar.
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Re: New SI5340-based RF Board in development
Thanks to everyone for the fast feedback. To answer questions in order:
1) Yes, I plan to release hardware and software files to this site as others have done. If there is demand, perhaps Bill can add this RF board to his stock.
2) My experience with the 74ALVC74D is much better than Bill's (my observed performance > 100 MHz; clean power is critical); I expect the '3233's to poop out before the 7474's. That said, the next version will use the SI5340 LVPECL differential output option to drive TI CDCM1802's. This is a slick part that operates up to 800MHz, divides by 1, 2, 4, or 8, and offers an LVCMOS output up to 200MHz. If the mixer could support it, this would put operation from 2200M to 2M within easy reach (see below).
3) I currently use the Out0 for Rx and Out2 for TX. Having an unused output between TX and Rx during split operation is intended to cut down on cross-talk during split operation.
4) For the TX and RX clocks, I do indeed use the inverted Si5340 output capability. These outputs are *exactly* 180 degrees out of phase (at least beyond my ability to measure any difference with a 2 GHz scope) when terminated correctly. I think the external FF's are important, because phase symmetry is critical in a Tayloe mixer (which is switching FETs on and off at both edges).
5) The SI5340 is indeed more expensive, but the performance/cost benefit is pretty good (at least to my way of thinking).
6) Soldering a 44-QFN is a bit of a challenge, but a stainless stencil is ~$10, which makes the temp-controlled hot-plate soldering technique pretty reliable.
7) As you can see, I was able to replace the 5351 (and the MF logic) with a 5340 and all of its support circuitry. It's tight, but it all fits, and it's a clean layout.
8) Yes, power consumption is higher, but dependent on output configuration. I added the required clean 3.3 to 1.8V supply to the prototype RF board in the available space with no problems.
9) The SI5340 has four main versions. Two of these, the Si5340A-D (up to ~1GHz with some holes) and Si5340B-D (up to 350MHz; perfect for this application) do support both fractional and integer divides. The fractional divide feature is what makes the part a good fit.
?
Now I have a question. While I think replacing the current RF board is a win, I have been giving serious thought to creating a separate VFO card down the road. This would free up room on the RF board to do other things (like add an optional non-Tayloe second mixer (to support 2M). There are lots of options (old-school Minicircuits mixer, or something like the AD831) I am experimenting with both. I am also experimenting with replacing the Teensy with a Raspberry Pi 5, which would give HDMI outputs, and more performance and memory than the T41"X" is ever likely to need.
73,
j
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Three fresh AA alkaline batteries in series will produce at least
4.8 volts, plenty for your test.? Three freshly charged NiMH
batteries probably won't.
73,
John, AA0VE
On 5/12/25 16:54, Bob Larkin via
groups.io wrote:
toggle quoted message
Show quoted text
It would be interesting to do a battery experiment,
but it is tricky to do.?? The voltage, per spec, should be 4.5
to 5.5 V.? Three AA's, when new, should do that, but barely.?? A
question comes up as to the source resistance, as we are
assuming that to be low when we assume it is the "reference test
case."? I'll try to run the 1808 off a new batteries (maybe D
cells) and see what happens.
?
The battery has advantages at low frequencies, around power
line frequencies.? But, I think our interest for radios is
mainly up 10 kHz or higher.? There, a good capacitor like the
100 uF ceramic would seem to be a really low impedance source.?
At 10 kHz, the cap looks like around Z = 0.002 - j0.16 which the
battery can't do.??? On the other hand, for applications that
include 10 to 100 Hz, the battery may be the standard.?? But
remember, at those frequencies are are multiple 1/f effects that
raise the noise floor, making outside noise less of an? issue.?
You can see those in the Codec page graphs.
?
Bob
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It would be interesting to do a battery experiment, but it is tricky to do.?? The voltage, per spec, should be 4.5 to 5.5 V.? Three AA's, when new, should do that, but barely.?? A question comes up as to the source resistance, as we are assuming that to be low when we assume it is the "reference test case."? I'll try to run the 1808 off a new batteries (maybe D cells) and see what happens.
?
The battery has advantages at low frequencies, around power line frequencies.? But, I think our interest for radios is mainly up 10 kHz or higher.? There, a good capacitor like the 100 uF ceramic would seem to be a really low impedance source.? At 10 kHz, the cap looks like around Z = 0.002 - j0.16 which the battery can't do.??? On the other hand, for applications that include 10 to 100 Hz, the battery may be the standard.?? But remember, at those frequencies are are multiple 1/f effects that raise the noise floor, making outside noise less of an? issue.? You can see those in the Codec page graphs.
?
Bob
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The short answer is that the 8-bits, or at least part of them are useful.? I'm attaching a plot of the output of the PCM1808 while receiving "no signal" to help explain what is happening.  The magenta trace is the direct 24-bit output of the ADC coming through AudioInputI2S_F32 path.? The blue trace is derived as the nearest I16 value to the 24-bit value.? Examine a couple of vertical pairs and it becomes obvious.
?
OK, two things happen.? The conversion increases the noise by a dB or so, as computed from the variances of the two data sets.? Probably more important is that the 16-bit noise no longer has a continuum of values, but in this case they are quantized to either -6, -7 or -8.? If that quantized signal is amplified up and applied to the human ear, it does not sound right and to some ears is offensive.? The classic solution is to add dither noise, which improves the sound, but also reduces the S/N and uses up dynamic range.?? All of this is avoided by the using the 24-bit data generated by the PCM1808, and the benefits are real.
?
On the question about the Teensy adapter with the SGTL5000.? If you look back at Figures 1 and 2 of the Codec page, you see that the SGTL5000 spectrum, when not in an idle tone, is about 6 dB noisier than the PCM1808.? When you are including idle tones, the spectrum is way higher.? So, running the SGTL5000 with 24 data is probably going to be of minimal value.?
?
Fun stuff.
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Re: Morse Code Tutor pcb...
Thanks Jack, Doug and Terrance!
Assuming I decide to pursue having a PCB made, what are the current challenges (if any) using the available board manufacturers? Are they still mostly in Asia, and how have the tariffs affected getting small quantities made?
On Monday, May 12, 2025 at 12:17:30 PM PDT, Terrance Robertson, KN6ZDE via groups.io <tmrob4@...> wrote:
Bruce has a groups.io for the Morse Code Tutor.? It has a link to his that seems to have all of the needed files.
|
Gary W9TD
John P
jjpurdum