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Hey Jack!

 

Ah yes the cap. Online costs have put me off the project for nearly a year. I just got the gumption to try and make my own butterfly capacitor, and it turned out pretty good for a first run at it. Of Course I did it wrong by using zinc plated hardware because I couldn't find bulk brass nuts. But just as a butterfly cap is works fine with about 25pf, and with the stators jumpered and used like a variable air cap it's 120pf. At out Ham Holiday I saw a high voltage commercial one like mine, but same capacitance. Anyhow the fear and mystery is gone, and I could make a bigger better one next time. Using a antenna calculator helps guess at the needed capacitance for what I will need next time. That one was just a (can I do it) kind of thing. ?I am gonna check out that mag loop group and see if they got anything I can learn. ?Laters.
Jack Purdum
 

Dennis Kidder (W6DQ) and I did start the Software Controlled Ham Radio group as a collection point for anyone who wants to blend our hobby with any software element. Obviously, I get a kick out of it and am learning some EE stuff along the way not easy for someone who's two years younger than dirt. Still it's been a blast.

As to the mag loop, I am a member of that group as well (https://groups.yahoo.com/neo/groups/MagLoop/info) and it has a lot of good information. I bought a vacuum variable capacitor with a 25KV rating as I also wanted to be able to use it with my 100W rig. The thing is about the size of a Volkswagen, so I'm backing off to an air variable cap, but with pretty healthy spacing. I'll experiment to see what kind of power I can use with it, but it should go to about 100W. I've lost two antennas this year to storms, so I'm hoping I can secure this one a little better. Should be fun...

Jack, W8TEE


From: John Smith via Groups.Io <johnlinux77@...>
To: [email protected]
Sent: Friday, July 28, 2017 6:50 PM
Subject: Re: [BITX20] Hey Jack!

Thanks for responding Jack. I thought you had a different group or site this stuff was coming from and shared here. I went back through my bookmarks and found the "Software controlled ham radio" Yahoo group. I haven't checked it in several months because the posts sound like a guys club with practically no focused content. Now it seems to have picked up a bit and saw your post about the Bitx 40 and a mag loop build. I almost talked myself out of it because of the cost of copper for a 40 meter band magnetic loop, which is between 17' and 34' in circumference. The plan was to have the mag loop for receive because of it's narrow bandwidth and noise rejection. And transmit with the low dipole that seems to be getting out better than originally expected. I just fell off topic too. Like I said, I thought this stuff was originally somewhere else. I also had plans to do something similar as the Forty-9er with another kit, but this BITX40 thing with the Raduino came along. Now I am feeling itchy for another project to play with. I'll go through the files section and your other group to collect everything in one spot. Thanks Jack.

I am including a link for a mag loop PDF because it seems like the definitive authority on the subject without talking over our heads. But still getting it all in there to explain it in detail. It might help someone curious about the magic antenna.
 

Thanks for responding Jack. I thought you had a different group or site this stuff was coming from and shared here. I went back through my bookmarks and found the "Software controlled ham radio" Yahoo group. I haven't checked it in several months because the posts sound like a guys club with practically no focused content. Now it seems to have picked up a bit and saw your post about the Bitx 40 and a mag loop build. I almost talked myself out of it because of the cost of copper for a 40 meter band magnetic loop, which is between 17' and 34' in circumference. The plan was to have the mag loop for receive because of it's narrow bandwidth and noise rejection. And transmit with the low dipole that seems to be getting out better than originally expected. I just fell off topic too. Like I said, I thought this stuff was originally somewhere else. I also had plans to do something similar as the Forty-9er with another kit, but this BITX40 thing with the Raduino came along. Now I am feeling itchy for another project to play with. I'll go through the files section and your other group to collect everything in one spot. Thanks Jack.

I am including a link for a mag loop PDF because it seems like the definitive authority on the subject without talking over our heads. But still getting it all in there to explain it in detail. It might help someone curious about the magic antenna.
Jack Purdum
 

Hi John:

I guess that most of the discussion is around what I'm doing to the BITX40, which I call my B40. I'm selling a PCB for those mods which, when done, includes:

? ? B40 mods: TFT color display, rotary encoder tuning, CW mode, speech processor, AGC, contest keyer, S meter, and supply voltage monitor. You can see the custom PCB?
? ? ? ? ? ? ? ? ? ? ? ? in the Files section of the users group. Search "W8TEE" and then sort by most recent date and look for Rel03 of the assembly manual. I'm redoing the software?
????????????????????????'cus I'm not happy with the way it works right now. I hope to have a release soon that handles frequency tuning with Fast Tune, and the ability to change fields?
????????????????????????smoothly on the display. You can see the display in the Photos section under my call. I sell the board for $7.50 (domestic).

? ? Antenna Analyzer: The PCB is sold by qrpguys.com. With a bare junk box, it costs about $50 to build, but has some nice features. They also have the assembly manual that
? ? ? ? ? ? ? ? ? ? ? ? you can download to see what it does. This was supposed to be in the Sept., 2017, issue of QST, but I just got a notice about 10 days ago that it has been "bumped"?
? ? ? ? ? ? ? ? ? ? ? ? to a later issue. No mention of when that will be.

? ? Forty-9er: This was published in the March, 2016, issue of QST and is a $10 40M 3W CW transceiver to which we added an LCD display and VFO. The original xcvr was by ? ? ? ? ? ? ? ? ? ? ?????????????Wayne Burdick and Doug Hendricks and built as part of the NorCal QRP group back in the '90's. My goal was to make a frequency-agile xcvr that could be built for?
? ? ? ? ? ? ? ? ? ? ? ?under $50. The rig is pictured below:

Inline image
? ? ? ? ? ? ? ? ? ? ? ? This also used a custom PCB, which Farrukh Zia sells (www.farrukhzia.com/k2zia) for about $6.50.

Finally, some members here have mentioned two of my books: Beginning C for Arduino and Arduino Projects for Amateur Radio. The programming book is written for the true beginning programmer and assumes no prior programming experience. The second has a number of ham radio related projects using microcontrollers. You don't have to know programming to make the projects work and full source code is available for all projects at:?

????????https://www.mhprofessional.com/9780071834056-usa-arduino-projects-for-amateur-radio-group

Both books are available (and reviewed) on Amazon.com. You can click on the "Look Inside" banner on the book cover and read the Table of Contents and even some of the narrative.

I think that covers it.

Jack, W8TEE

From: John Smith via Groups.Io <johnlinux77@...>
To: [email protected]
Sent: Friday, July 28, 2017 2:23 PM
Subject: [BITX20] Hey Jack!

I have been coming to this site everyday and reading what's new, and little by little I see your other stuff creeping in. And was wondering if would post a link to your "other stuff" so I can get the full rundown on your for BITX40 DDS VFO, and the antenna analyzer, and so on. I am only getting pieces of it here, and would like to know more about it. I also wondered if you might be planning a book or something free with "Other stuff for the BITX'er". I can't just buy, I have to brew. And it's nice to find a funnel for all the information.


John P
 

I wish some moderator of this site could merge the millions of threads about Jack's VFO into one.
--
John - WA2FZW
 

I have been coming to this site everyday and reading what's new, and little by little I see your other stuff creeping in. And was wondering if would post a link to your "other stuff" so I can get the full rundown on your for BITX40 DDS VFO, and the antenna analyzer, and so on. I am only getting pieces of it here, and would like to know more about it. I also wondered if you might be planning a book or something free with "Other stuff for the BITX'er". I can't just buy, I have to brew. And it's nice to find a funnel for all the information.

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