The 147.120 Tech Net Blog

Well, mostly conquered
 
Jim has a capacitor that is way more than 50 PF. So it’s time to learn series and parallel capacitance, resonant circuits and probably something else. No, I’m not going to dive into it here, admitingly I have to learn that myself! However, there do seem to be some calculators out and about that should help.

As you can see in the picture his VFO covers a lot more than just the 20 meter band. For some that may be just fine. What it does, though, is limit the ‘resolution’ of your tuning dial. The radio does have a nice fine tune adjustment to compensate for that.

 
Another big breakthrough at the Party was the flashing of Das U-Boot. Yah, we have flashing Das U-Boot! Dave sucessfully formatted an SD card the way the NGW100 likes, we moved the Atmel Flash Upgrade Utility to the SD card, and told U-Boot to load the image. It was cool! Took seconds flat and now reports U-Boot 2010.8.
 

This is important to anyone who has an NGW100 as this upgrades the ‘bootloader’ in the board to be able to read 2GB cards. The U-Boot bootloader that ships preloaded in the card won’t read the cards with large blocks. We’ve been stuck with older cards, usually 64 and 128 MB. Dave had one card that was 1GB with the small block setup. That’s the card we ended up using to load the flash image.

 

We had quite the group for the first Wednesday of the month. Remember there are several other groups that meet the first Wednesday of the month so the Technet and Tech Party are usually kind of light. We did great this week though!

Remember EVERYONE is invited to our group – you don’t have to be involved in any of our current projects to attend. The social value of this group is immeasurable! From time to time the group leader does focus the attention of the group to a specific point, but other than that this is definitely a multitasking group.
 

 
Let the knowledge flow

It is absolutely the best thing in the world to have a room full of Elmers an aspiring techs. Here is Jims VFO showing the large range of coverage he has, with Vern and Dave in the background digging in to their projects.
 
 
 

 
Here is a closer view of Jims setup and the frequency. Also note the power supply showing 80 mA current at 13.8v. Keep in mind the entire circuit is not powered, just the VFO and display.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
See you next week!
Come out to next weeks Tech Party! Log in to the net on 147.120 Wednesday at 8pm if you can’t make it in person. There’s always something good going on and now n then there’s munchies! Never be afraid to bring munchies – you become an instant hero of the 147120 Tech Crew ;]

Last Wednesdays tech net was a raving success! Although there were only a handful of us there we finalized the defeat of our shortcomings with the Bitx20 VFO. What’s best, is that we used the tools that WE BUILT to test it! woo hoo!!
 

Verns VFO
is the first working properly. With the caps that Dave got from Mouser Electronics (Part # 23PW156; Film capacitors; styrene 50V 560pF) and the replacement variable cap, this puppy is dead on and unbelievably stable! The poor little am radio cap just wasn’t happy; it was shorted or possibly corroded, either way it was ‘jumpy’ every time we tried to do anything with it and we just couldn’t figure out the little trimmers on the back.
 
Replaced the Capacitor
The original was a little rusty or something

I had picked up a small ‘offcenter’ variable cap off ebay some time ago. The value is the same as the one in the kit so I was confident it would plug right in. I had built a small reduction on a 6:1 vernier giving a total of 30:1. Yup, it takes 15 turns of the knob to go from one end of the band to the other – 10 KHz per turn at the bottom end, and 20 KHz per turn at the top. Not bad!!

We used the FLL frequency counter kit we had built a couple months ago to test the VFO. It turned out to be a nice little tool for tuning the circuits in the BItx20. Verns ended up having a coverage of apx 3.998 to 4.352 – again very nice! Verns price for the reduction? He has to make the transceiver look really good ;]
 
The Perfect Setup?
Good enough for Nate!

The test was done on top of Nates neat setup he is building for his breadboard. He found a ‘briefcase’ type box at Skycraft and attached his breadboards on top of it, leaving room inside for all his accessories. In this test we used the power buses to make hookup much easier. Below is a view from another angle. Note the power supply showing the unit drawing 90 mA at 12v – backlight and all! Of course just the VFO and Frequency Counter are powered right now.

We really did have a lot of fun with this one. Vern had to rewind his toroid several times, finally finding a smaller diameter wire in order to put his final 54 turns on the core. It is spec’d at 50 turns, but it ended up being too high in frequency. When he tried to go over 50, it was not in a single layer winding with the wire provided to the inductance was way off. The final verdict – 54 turns with #32 wire on the core provided. Yay!

Vern really likes hot glue. Every time he wound a core he’d glue it down for testing. We finally convinced him to just glue the final result down. When dealing with things like this, like the inductor in an oscillator, physical stability is very important. Gluing the core down will keep it from moving and causing minute ‘microphonics.’ Good job Vern.
 

The Fine Tune Control gives almost a perfect 3 KHz shift – a little over 1.5 KHz each side of center. That’s extremely nice as all you have to do is tune ‘em in so you can hear ‘em with the main tune, and then adjust ‘em so you can understand ‘em with the fine tune. As designed and described!

So we were able to conquer the VFO – now on to the next stage. There are several builders going on to the audio stage next, a couple into the mixers. Next week we’ll discuss who is where and what new challenges we may face.
 
 
The Meeting Was A Smash
and we had a good time, too!

All in all we had a great tech experience, a great tech net, and a great result from the evening! I hope to see you next week at the tech party or at least check you in to the Wednesday Night Tech Net.

TECH ON!!

On Wednesday at about 8:00 pm local time is the 147.120 Tech Net.
You can find the Tech Net on the 147.120 MHz repeater (KJ4PLD) with a CTCSS tone of 103.5

Here Tracy (N4LGH) acting as the Net Op at Vern’s Barber shop.

Trying to figure things out by experimentation can be very difficult, especially when you’re not sure what you’re looking for or dealing with. There are many unknowns in most experiments and we need a way to control the experiment as much as possible to isolate the data you’re looking for.

The Scientific Method is a way of looking at a problem and following a controlled set of steps to solve it. Keeping all known elements constant makes it easier to isolate or identify the unknowns.

Join us this week for a discussion on The Scientific Method. Do a little research on the subject (Google ‘the scientific research’ with or without the quote) and be prepared to engage in a discussion that is sure to enlighten your tech abilities!

See you all Wednesday evening at 8pm on the 147.120!
Tracy N4LGH

Hello Tech Fans!

This coming Wednesday we will be discussing Test and Measurement Equipment – what it is, how to use it, and hopefully personal experiences of our participants. This should be a fantastic conversation about testing and measuring all things ham radio.

See you Wednesday at 8!
Tracy N4LGH

This weeks Technet will be hosted by Phil, AI4OF. Phil is an extremely knowledgeable individual that has a way of explaining things simply and usually with good examples.

I have a one-time financial opportunity that I cannot refuse … I guess we all have a price? hihi we’re all plagued with having to pay the bills ;]

Make it a great turnout for Phil and thank him for filling in last minute!

Thanks Phil!
Tracy N4LGH

I want to apologize to everyone who expected a Tech Net tonight. I had a series of personal incidents that prevented me from getting on the air tonight. I’m just now getting in and still, I have no antenna!!

This WILL be solved before next weeks net!

I WILL be at the build meeting tomorrow!

Thanks for your patience,

Tracy N4LGH

Meeting #1

This was held on 30th of Nov 2009.

Talked about tools needed to assemble the project, soldering and the assembly instuctions that we are going to use.

I mentioned that the discussion list was on YahooGroups which can be found from here.

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Other pictures

73,

David — KC4ZVW

Hello again. I would like to share another resource that will inspire, inform, and astound. Hans Summers, G0UPL, is an Electronic Wizard of the Twelfth Degree (see the International Brotherhood of Electronic Wizards Handbook for further information). He has built a website that abounds with inspiration. His projects are visual and functional. He likes to use tubes and will spurn convention to create a visually appealing project. This is art. The amount of information is sure to keep you busy and should be bookmarked for reference.  I am interested in his extensive information on Huff and Puff Oscillator stabilizers and identifying crystal parameters. He builds his own test equipment and documents so that we can follow in his path. Several QRSS projects are detailed. I have added QRSS to my list of future projects. Thank you Hans, for sharing a lifetime of experience at HansSummers.com. 73

Robin

Well, the BitX20 project is officially launching. Patrick KJ4JTK is keeping the list of participants so contact him to get involved. His email is pberry26 at yahoo dot com.

Here are the basics -

This is a course designed to teach the General Class Amateur Radio License theory by building a basic 20 meter SSB radio, illustrating the electronic theory required to pass the General Class License Exam. All sections of the General Class Exam will be covered in the course and the exam will be administered at the end of the course. The successful student will emerge from the course with a quality SSB radio and the license to operate it.

Registration must be in by October 31st
The course starts November 30th

Price for non-members is $200 which includes one year membership.
Price for existing members is $185 with lifetime members at $175. “Audit’ courses are available at $135 each for either the General Class License only or the BitX20 Radio only.

Meetings will be on Mondays and Thursdays from 7pm-9pm at KI4SDY Verns shop located basically at Ronald Regan Parkway and State Road 434. Holiday dates will be skipped.

There is a list of suggested tools to successfully build the radio. ‘Loaners’ will be available on a limited basis. There will be test equipment present at some of the building sessions.

This is sure to be a fun and productive project. Those participating on any level should grow in the knowledge of how SSB radio’s work, and a better understanding of basic electronic theory.

Q/A sessions will be handled on the Wednesday Night Tech Net as well as the Monday and Thursday sessions.

Contact Patrick to get on the list. Once registration is closed we will accept payment for the course and project.

Completion of the class / project will be just before the Orlando Hamcation and we will have a ‘Brag Booth’ there.

Feel free to ask any questions of myself or the appropriate parties listed here. The Wednesday Night Tech Net is always a good place to ask questions about this class and project.

Tracy N4LGH

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