开云体育

Hi all -

As of this afternoon my homebrew SBITX is receiving.? The architecture uses my own homebrew analog transceiver connected to a homebrew digital board running the SBITX software.? The digital board consists of a MIKROEElectronica WM3871 codec prototype board, an SI-5351 module and a Pi 3B+ with 7" touch display.? For the analog transceiver I built a 40MHz 25KHZ bandwidth crystal filter and put in a bidirectiona IF module that I had built for another project.? The IF uses? ADE-1 mixers on either side of the filters.? The IF amplifiers are bi-directional Plessy Manpack circuits directly from EMRFD courtesy of Pete Juliano, N6QW.? I used the board from the first version of Pete's SimpleSSB that built during the pandemic.? I build the audio low noise amplifier from the SBITX schematic to drive the codec.??

Here are some video links and pictures:

1.
2.
3.

Here is what it looks like on the bench:



And here is what is behind the magic curtain...



Next up I will build the front end LPF, and the LM380 audio amplifier.? With very little effort after thatI can get it transmitting QQRP - but I want to build the switchable output LPFs and a couple of stages of RF amplification.? I may end up using? a pair of RD16HHF1s for the final.? I've built a couple of those and they work well.

It would be great to hear if others are doing anything similar!

73,
Dean
KK4DAS

73.
Dean
KK4DAS

Thank you Dean for the inspiration. Apologies to the rest of the group, as we are taking this a bit off-topic.
I help run a Hackspace in the UK, and want to run something similar at an exhibition in a couple of months to show how the R Pi can be used in ham radio. I have just bought a MikroE module and already have an Si-5351board. I was going to drive a couple of mixers and demonstrate some low power transmit to an adjacent SDR rx, but maybe the reception is more impressive. I love the construction you have used.
Another project I have in mind is to upgrade a Digitrex Electronics MPX-Mini? HF Tx/Rx kit that I bought in the early 90's that I never fully completed. It uses direct conversion and a huff&puff synthesiser. Very much in need of an upgrade.
Tony
G3OVH

Tony,
you don't need to apologize for going off topic. After all, you are on the topic.
We all build or transform something according to our vision.
If anyone has good ideas to share, I'm always happy to read them.
--
Gyula HA3HZ

Tony,

That sounds like a great demonstration project. The receiver wasn't terribly difficult to get going..? if you want the full 25 KHz bandwidth on the waterfall. You'll need to build a filter. I was able to get Crystal's from Mouser and build a suitable one.? The IF stage I built is bi-directional. Is his relay switching and will alternate between receive and transmit. However, if you only want to build the receive side it's really just two diode ring mixers and two 2N3904 amplifiers. Happy to share any details with you if you're interested. The SBITX uses the LINE input on the codec so you need an audio amplifier after the filter to bring the level up.? I just copied the one from the SBITX schematic.

Good luck with your project,
73,
Dean
KK4DAS

Hi.... Just a quick update. I'm at that stage of a project where rapid progress is possible. I added the front end, low pass filter and a variable gain RF pre-amplifier. I also adjusted the code for my SI 5351 calibration and I'm now perfectly on frequency.

I have a 40 m Digitrex. Would love to get a copy of the manual. Not sure what mic to use with it. Can't believe someone else has one of these! No info online at all!

73
KG8JK

Dean - enjoyed seeing you discuss your sBitx build on the SolderSmoke Podcast!

73; Steve, N3SB

Thanks for the replay Tony. I really have no idea about any of it. I picked it up fully assembled. Receives SSB and CW fine. I know it transmits, just not sure how well. Anything you can send me would be great! my email is my call @ qsl.net.

Thank you!
kg8jk

The podcast was fun and it prompted me to update my blog -?

Take a look at my latest blog post:

73,
Dean?
KK4DAS

That's a great blog, Dean - lots of useful insights. And I am impressed that Farhan has taken time out to offer you assistance. What an impressive forum this is!?
73?
Tony