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IMD performance of D4D
Adam Rong
Folks, One of potential customers asked about the IMD performance and I think it is a good question. I have to clarify here when I wrote spurious suppression of -50dBc. It is actually for harmonics of 2nd and 3rd and other parasitic oscillations. If we check closely near the carrier frequency with a spectrum analyzer, the IMD products of 3rd, 5th are quite strong. The measured IMD 3rd is not good, which will generate strong overtone in waterfall spectrum and cause nearby channel interference. During design phase, I have noticed it but I have to balance the RF output from the design simplicity with this spec. I also noticed that the carrier leakage without audio modulation is strong too, and it is even higher than the 3rd IMD products. Those are the facts and I hope you can understand and help improve if you can. Thank you. Thanks, Adam Rong
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D4D: Documentations
Adam Rong
Folks,
I have created folders in the files and photos sections. I will update the files regularly. Before the manual is published, you can refer to the step by step building photos here in Chinese: Thanks, Adam
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Sorry, but we are not attending Hamvention this year
Adam Rong
Folks,
Due to an unexpected reason, the show of D4D in Hamvention is cancelled. However, we believe that D4D is a promising product and you are welcome to introduce to your local clubs, forums or magazines. The build and test by dozens of Chinese local hams went very well in the last a few days, and we also knew the limitations of this tiny product. I will start shipping from May 20. I hope you will like it. Thanks, Adam, BD6CR
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Re: D4D: Documentations
Adam Rong
Software settings in Chinese. Try Google translation if you cannot fully understand from pictures.
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New file uploaded to crkits@groups.io
crkits@groups.io Notification <crkits+notification@...>
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the crkits@groups.io group. File: d4dpartlist20190519forMP.xls Uploaded By: Adam Rong Description: You can access this file at the URL: Cheers,
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New file uploaded to crkits@groups.io
crkits@groups.io Notification <crkits+notification@...>
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the crkits@groups.io group. File: d4dqgreva.pdf Uploaded By: Adam Rong Description: You can access this file at the URL: Cheers,
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Re: IMD performance of D4D
Adam Rong
Gang,
Compared with 2nd and 3rd harmonics, the adjacent channel IMD products are higher. I did try to attenuate the input audio and it will improve but the result was not so satisfying. In this way, I have decided to remove C20 and C23 to change the LPF from elliptical to regular filter. It will improve the impedance matching with the antenna at the cost of higher 2nd harmonics. I will add this note into the full manual. Beta testers, please remove C20 and C23 as well. For serious builders, please follow this page to try: https://pa3csg.nl/?page_id=40 Thanks, Adam
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New file uploaded to crkits@groups.io
crkits@groups.io Notification <crkits+notification@...>
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the crkits@groups.io group. File: D4D kit manual.pdf Uploaded By: Adam Rong Description: You can access this file at the URL: Cheers,
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Poor boys DSB FT8
Adam Rong
Folks, Anyone has access to this page? It seems new but I am curious about the design concept. Thanks, Adam
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D4D: First Shipment
Adam Rong
Folks,
I just shipped three boxes yesterday to my shipping agent and today they will ship to worldwide. The backlog is not cleared so I will ship some more next Monday. After shipping, I will update tracking number in PayPal. The full manual preview draft is already in the files section. I will take time to improve it this week. You will see a brand new version when you get the kit. Thanks, Adam
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D4D for 6m band?
Hi Adam, congrats on fantastic product idea! I checked the archive and did not find the answer so created new topic: did you consider making a 6m version of the D4D TRX? As most of the traffic on the "magic band" is FT8 it would be perfect device to take for travel - combined with Raspberry Pi and small, portable antenna... If possible - one for me please! 73 de DL3GJ Greg
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Re: D4D for 6m band?
Adam Rong
Greg,
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It could be challenging due to thermal drift of the crystal. A TCXO is very expensive to customize. However, we can give it a try to build a sample. Thanks, Adam
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Re: D4D: First Shipment
Adam Rong
Folks, I have updated PayPal with all the tracking numbers. Orders on May 18 and later will be shipped next Monday. I shipped by post office with tracking, so you can track it on your local post office web site in a few days. For instance, US guys can track on USPS tracking site at You can also track on EMS web site in China here: Normally it will take 10-20 days, so give it some patience and you will get it anyway. Thanks, Adam
On Tue, May 21, 2019 at 9:19 AM Adam Rong via Groups.Io <rongxh=gmail.com@groups.io> wrote: Folks, --
Thanks, Adam Rong
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Re: IMD performance of D4D
Adam Rong
Gang,
Follow up on this IMD topic: Two domestic customers reported that D4D won't work with automatic tuner very well. One customer fixed it by switching off power supply of the tuner, the other has no fix yet. I guess it is related with IMD products. The automatic tuner will detect signal frequency and tune to the best point, but with strong IMD products, the auto tuner just failed to work. Thanks, Adam
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Re: D4D for 6m band?
k5dez@...
I got the idea from a Youtuber....(TRXBench) and tried it on a cheap Xverter and it seems to work OK. Why not try soldering a PTC resistor to the crystal to help stabilize it? It would be a very cheap TCXO.....It would NOT be an industry standard of course but it might work well enough. Just a thought.
Tim - K5DEZ
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Re: D4D for 6m band?
Adam Rong
Tim, Thanks, this is something that we can do. Thanks, Adam
On Wed, May 22, 2019 at 7:17 AM <k5dez@q.com> wrote: I got the idea from a Youtuber....(TRXBench) and tried it on a cheap Xverter and it seems to work OK. Why not try soldering a PTC resistor to the crystal to help stabilize it? It would be a very cheap TCXO.....It would NOT be an industry standard of course but it might work well enough. Just a thought. --
Thanks, Adam Rong
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New file uploaded to crkits@groups.io
crkits@groups.io Notification <crkits+notification@...>
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the crkits@groups.io group. File: D4D kit manual 0523.pdf Uploaded By: Adam Rong Description: You can access this file at the URL: Cheers,
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Re: IMD performance of D4D
The D4D works great with my LDG Z-817 auto antenna tuner.
73! Jim - KH2SR
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Re: IMD performance of D4D
Should jumper wires be installed in place of C20 & C23 after they are removed?
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Re: IMD performance of D4D
Adam Rong
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