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Saturday, November 2, 2024

More Background on the Mythbuster II Rig (and a short video)

Above is a short clip of me hearing an old friend on the new receiver.  TRGHS. 

A couple of guys on Facebook asked for a schematic for this rig.  I don't really have one -- as you will see it is a collection of different circuits from lots of different sources.  I was also thinking that if you need a schematic for a rig like this, you probably shouldn't try to build a rig like this.  But in an effort to be nice, I supply here some background info on some of the circuitry and parts sources.  And no, I don't have BOMs nor Gerber files.   

More info on the Yaesu VFO is here:

https://soldersmoke.blogspot.com/2021/07/mythbuster-video-3-using-vfo-from-yaesu.html

The VFO is kind of high in frequency. But it is very stable. I can't really take credit for this -- the credit goes to Yaesu. But I like the circuit because it is all analog and all discrete component. It even has a split stator temperature compensation variable cap! At Pete's recommendation, I originally bought these boxes thinking that I'd just get the anti-backlash gears and the reduction drives. But the sellers always sent the entire VFO boxes. They even come with a "clarifier" circuit which I now use as an "up 5-10" feature that lets me work the DX-peditions on 20.

As for the tape, I got mine from Amazon. It has conductive adhesive:
https://www.amazon.com/gp/product/B07QQJ4MX1/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The boards for the IF Termination Insensitive Amplifiers come from Todd K7 TFC at Mostly DIY RF:  https://mostlydiyrf.com/tia/

The little LM386 boards that I have been using are available here: https://www.amazon.com/dp/B00LNACGTY?ref=ppx_yo2ov_dt_b_fed_asin_title  I precede it with one stage of AF amplification from the original BITX 20 sechematic.  I put a 10K pot between this stage and the LM386 board. 

Here is the Amazon source for the 1/8 inch plywood that I will use for the case (I have used up all the pandemic treadmill packing material):  

7 comments:

  1. Your SolderSmoke blog was one of the first resources I discovered back in 2007 when I became active again in ham radio after a long hiatus away from the hobby. Your blog and podcast were directly responsible in getting me started building an actual transceiver; without your building examples and stories I doubt I would have attempted such an undertaking. I want to thank you Bill, (and Pete and Dean) for taking the time and effort to share your work with those with "the knack"; i.e. us. The SolderSmoke website is my first stop every morning to give me the inspiration to build and to catch up on what's important in the homebrew radio world. It would be a sad and dark day indeed without SolderSmoke. Please keep the SolderSmoke podcast and blog going. There are thousands of Amateur Radio websites, blogs, and resources out there, but your's is one of only a very few that bring back that excitement we felt back in our younger days when we first discovered the electronics hobby; of simple but solid circuits that can be built with a modest investment of time and resources. You demonstrate the magic and joy of homebrewing, something a textbook treatment of the subject can't do, you are our "Jean Shepherd" for these times. True, Amateur Radio is a hobby enjoyed by a small subset of the population, that those that actually build their own transceivers from scratch is an infinitesimal subset of that group. We're kind of like the men that walked on the moon, there are not many of us but we share a unique position in the world that deserves a place to collaborate and celebrate our work. Thank you Bill for being there for us.

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    1. Thanks Rick: Your message provided a welcome morale boost. I have your QSL on the wall OM. 73 Bill

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  2. I whole heartedly agree with what N3FJZ said. I have never commented before but felt after reading that post i had to.
    Thank you Bill,Pete and Dean.
    Regards, John KE2AMP

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  3. Lovely VFO. Reminds me of my first and only Yaesu transceiver bought way back in 1977, an FT200. 73 Paul VK3HN.

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  4. Thank you for the parts source info! 👍

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  5. I consider the podcast to be the best on the web.

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