Fun Schematics

I enjoy looking at hand drawn schematics....

http://soldersmoke.blogspot.com/2008/10/i-shift-to-fsk-on-30-meter-qrss.html

Here is "gimmick capacitor" in a simple oscillator circuit. Bill over at Soldersmoke is playing with FSK keyed QRSS. This is an old post explaining about "gimmick" capacitors compared to today where he is using an LED as a varicap in a different QRSS rig.

Fun home brew stuff.

73 de NG0R

Putting parts away

My electrical workbench is in a different room than where my radio gear is located. I decided about 2 years ago to separate my spaces as they have different requirements.

I like to be able to work on projects for several days and need the ability to be able to stop and walk away as other commitments come up and the come back to a project later. The workbench is a small room in the basement largely unused/visited by the rest of the family. (Perfect for leaving a project on the bench for several evenings.)

Image below shows a portion of the room that hosts my workbench.


Tonight I spent a couple of hours sorting some more capacitors, LEDs, and resistors.


I have a lot of these medium sized plastic parts containers.


I have a lot more parts boxes than what is in this picture. I am trying to sort everything and label the containers with basic information about what "category" of parts they contain. Eventually I am going to need to build a couple of shelves that are dedicated to holding the parts boxes.

12 months ago you probably would have laughed because I had virtually no parts on hand. I had a very small junk box. I would call N0FP to "borrow" 1 or 2 pieces of x or y. I have made point recently of acquiring a lot of standard components. When I started to look at the kinds of projects I am building I noticed a HUGE amount of overlap in the common components.  Mouser, Digikey and eBay have been my friends recently.

It is nice to be able to do some design work in the shack/office and then take the schematic to workbench, grab a couple of parts boxes, and then melt some solder to make a circuit.

Yeah... my bench is mess... I was sorting parts and boxes tonight when I took the pictures while cleaning.

73 de NG0R

LEDs as a varicap diode

Hans Summers is a genius....


http://www.hanssummers.com/varicap

I have heard about people using LEDs as varicaps but I have never gotten around to looking into the idea. I am working on a project/design right now which will probably need a Varactor diode (varicap).

I saw a link on "The Knights" email reflector with Bill and Hans chatting back and forth about the topic and a link to Hans' site for more details.

Hans is a wild man, lots of graphs and data. I really like the OCD (Obsessive Compulsive Disorder) approach to the data... I would expect nothing less.  :-)

73 de NG0R

Linux : Sync/Backup USB Drives

I have a lot of content on my home network but backing it up has always been a pain.

When I say content I mean everything in the computing world that is important to me like all of my images, some video files,  CAD files, schematics, reference documents, install files, machine backups, automation scripts, ham radio logs, lots of engineering notes, etc.

• When my network was W2K3 and XP I used Robocopy to backup the W2K3 network shares to an external USB drive every two weeks. (Sometimes I was better about the two week rotation than other times.)
  
  
• As I started to transition from Windows (servers and workstations) to Linux and my network became more of a hybrid I bought a 1TB external USB drive. I moved most of the Windows and Linux content to this drive as I decommissioned machines. 
  
  I had numbered several other external USB drives and would rotate which one I used every 2 weeks for the backup of the main USB drive. Once again I used Robocopy to do the heavy lifting. The initial mirror took 6-8 hours to run (a good overnight job) and then additional syncs generally ran in less than 1-2 hours.
  
  
• Now that my network is about 95% Linux I need to rotate the backup USB drive(s) again as it has been about 30 days. I am going to use RSYNC to mirror the primary 1TB USB drive to the numbered USB drives every two weeks or so.

• I live in the middle of rural Minnesota so using a service like Amazon S3 or one of the other Internet backup services is unrealistic given my bandwidth combined with the amount of content that I have today and produce on-going. (RAW photos from my digital camera + any video work that I am producing is too large for the humble amount of Internet connectivity that I have.)
  
  At some point I should just take the USB drive some place with ubber Internet connectivity and upload it to S3 (or whoever) and then try to let the nightly jobs keep it in sync... but that will take some research to figure out.
  
  My answer to this issue for the time being is that I will need to get a safety deposit box at the bank and then rotate several numbered USB drives between the house and safety deposit box at the bank for my off-site rotation.
  
  
• Today I don't backup any of the PCs on our LAN. I probably should look at backing up my PC and the Amateur Radio PC and/or at least the contents of my home directories.  That might be a phase two thing as I refresh my backup process as part of the Linux migration.
  
  

Here is how the USB mirror process works:
rsync -vrlptg --delete "/media/SOURCEUSB/" "/media/TARGETUSB/"
replace SOURCEUSB and TARGETUSB with the name of the drive

This should provide a "mirror" between the two locations.

rsync flags:
# -v   verbose output
# -r   recurse into directories
# -l   copy symlinks as symlinks
# -p   preserve permissions
# -t   preserve times
# -g   preserve group
# --delete   delete extraneous files from dest dirs
# --delete-before   receiver deletes before transfer (default)
# --delete-during   receiver deletes during xfer, not before
# --delete-delay   find deletions during, delete after
# --delete-after   receiver deletes after transfer, not before

You can confirm that the drive/content sizes match with:
df -h

For other Linux newbies (like me) here is a link to a webpage that provides some simple background on the rsync backup process I am using.
http://www.basicallytech.com/blog/index.php?/archives/73-Using-a-USB-external-hard-disk-for-backups-with-Linux.html

Scott Hanselman has a great post on the Family Backup Strategy that I like a lot:
http://www.hanselman.com/blog/OnLosingDataAndAFamilyBackupStrategy.aspx

EFHWA notes

I am planning to build a tuner box for an EFHWA (End Fed Half Wavelength Antenna) and was doing some research on what other people have done. (I have posted links in previous posts as well.)


http://www.qsl.net/va3rr/sw30/30metres.htm

VA3RR has a nice design. He has a tuner + a swr bridge (aka LED) that he can use for the tune up process. I think that Bob AD7BP was looking at building something like this as well.

I have the parts on hand to build a QRP version and a 100w version of the tuner box. I probably have the pieces to build the bridge as well. I am inclined to build a 100w version. Recently two of my three sons got their Technician license so I need to think about how to include them in the hobby. QRP is not a sport that I would throw a new ham into... it is better suited to an older hobbyist that already has Q's in the log and is looking for a challenge.

I am thinking that a nice EFHWA tuner + some pre-cut antenna leads will work very nicely with the FT-450AT that boys have. We recently bought the FT450AT to take on our camping trips, Field Day, and weekend visits to our extended relatives. We would like to have a nice little box with everything needed to play HF away from home. (I still would prefer to use my K2 but that is a QRP only rig.)

Maybe we can prototype the EFHWA on Sunday at the work bench.

73 de NG0R

No Rain in Kingston

We live in Kingston Minnesota. It is a small community about 53 miles north-west of the Twin Cities.

There is something odd about this area. We are on some sort of weather line. The heavy rains tend to run about 12 miles south of us or 8-10 miles north of us. Unless we have a huge widespread event we generally don't get too much rain here.

A great example is that on a regular basis the area between Dassel and Hutchinson will get 2-3 inch rains  and for the same event we will generally get .25-.5 inches of rain in our bucket.

The radar image above is a great example. Granted this is only a trace so far, but when you watch it loop on the radar the initial rain front will break up as it approaches us and then reform a few miles away on the other side of us.

Your laughing at this post... but talk to the locals and they will back up this story 100%. As of June this year we will have lived in this house for 5 years. Our initial summer here was extremely wet (which figures because we did not have any landscaping completed, no grass, a rough driveway, etc) ever since then we have had drought years.

So far for this season we have only had .5 inches of rain in our rain gauge since our snow melted. (That .5" was about 12 days ago.)

Circuit Diagram

Another classic from xkcd....

Fargo Hamfest 2010

Saturday 4/17 Ben and I attended the Fargo hamfest.  This is our second year going up there and certainly not our last. For a small town they put on a great event. Lots of radio & electronics gear. I am very pleased with the deals and the amount of homebrew stuff that is available.


It is not a hamfest unless you have some vacuum tubes, crystals, and old soldering irons.  :-)





OK... enough humor... there were some nice radios


At least 4 or 5 tables with transistors


We spent 90 minutes at the hamfest, walked around twice, and filled up
our backpack with stuff!  $26 spent at three tables.

Table 1 - $1.00
2 small IF amps (looks like a school project or a test fixture)
2 RG-174-->BNC pigtails for projects
1 medium size bag of RG-174 cables (good lengths)

Table 2 - $5.00
1 Old desk mic (will probably use it for my Retro 75 AM project)

Table 3 $20.00
1 Hammarlund cap 25-150pF
37 - 1000pF caps
136 - 2N4250 PNP
Box of pilot lamps and LEDs
200 - 2n3391A NPN
16 - .1mF caps
84 - 1200pF caps
Bag of misc transistors
7 - 0.047uF caps
100 - 175pF caps
2 boxes of ceramic standoffs
15 - 2.47m resistors 1%
30 - 4uF caps
8 - 49.9k resistors 1%
1 box of SS standoffs
15 - 1uF caps
15 - .004uF caps
15 - 560k resistors 1%
30 - 2k resistors 1%
15 - 400m resistors 1%
15 - Raytheon 7319 PNP
45 - Motorola 049-001 7307N PNP
45 - Raytheon 7317
6 - Dickson D13013 transistors
2 - 15uH inductors
2 - 82uH inductors
2 - 100uH inductors

It will take me several evenings to get all of the parts sorted into the proper storage boxes. Tonight I took care of most of the transistors.

Ben and I had a good time on our trip, we enjoyed the hamfest, and we got a LOT of parts at a killer price.

Next weekend (4/24/2010) we are headed to Iowa to visit some extended family. While we are there will visit the Des Moines hamfest.

73 de NG0R

QRSS Oscillator for 30m

Tonight was a lot of fun. I finally got back to the work bench to run a couple of tests. I have a bunch of crystals for 10.140MHz but they seem really be 10.138MHz.  This is NOT in the QRSS sub band and I figured that I could probably "pull" the crystal up to 10.140.100 sub band. --The real question is what size capacitor would it take.

I drew up a quick schematic (on paper) that looks something like the image above. I then pulled out a couple of variable capacitors. Initially I tried a 12-250pF and then moved to a 4pF-40pF. The magic seems to be about 15-18pF to it to the proper sub band for QRSS operation.



I was surprised at how stable it was. I had it running on workbench for about an hour and it only moved about 1 hertz across 10 minutes and no more than 2-3 hertz in an hour. That is pretty darn stable for a breadboard.



The image below shows the fundamental signal and the first five harmonics. It is pretty rich so I could easily pick out and tune any (or many others) with a tank circuit if needed.


10MHz x 10dB divisions

This is more than stable enough for QRSS operation.  You would need to add a couple of simple gain stages with some small signal parts like a PN2222 or 2N3904 running in class A + a simple transistor final + a low pass filter. (All of these other stages are listed on this blog if you search around a bit through previous posts.)

Some notes about the variable capacitors:
12-250pF will cover 10,138,466 to 10,140,620 hertz
4-40pF will cover 10,139,228 to 10,142,495 hertz
I found that 15-18pf was needed to get into the QRSS sub band with my components.


Next Steps:

• I need to test a couple of different ideas for what I am going to use for my "finals"
• Test how I want to "key" the whole transmit stage
• Layout a circuit board for a prototype

73 de NG0R

Skywarn 2010

Ben (N2BEN) and I attended the Skywarn class in Litchfield, MN today.

Above - KG0U explains updrafts and the rain-free-base.

Below - Ben (9) looks on as the lecture and slides continue


Below - Pretty nice attendance levels for a rural county.


Some quick notes on Skywarn Repeaters in Central Minnesota
(Stuff near our QTH is listed first, then places we visit & camp.)

Meeker County Repeater
Darwin: 146.865 (PL146.2)

McLeod County Repeater
Hutchinson: 147.375 (PL146.2)

Western Twin Cities Repeater
Maple Plain: 147.100 (PL144.8)

Minneapolis/St Paul Repeaters
Northern metro Primary : 146.850
Southern metro Primary : 147.210 (PL100)

Kandiyohi County Repeater
Willmar: 146.910

Stearns County
Avon 147.105 (PL85.4)

Redwood County
Redwood Falls: 146.865 (PL151.4)

Benton County
Foley: 147.075 (PL85.4)

Douglas County
Alexandria: 146.790

Hub (for rural county net control --> NWC)
Becker: 147.345 + offset (PL85.4)

A nice map from the NWS on Minnesota Skywarn Repeaters
http://www.crh.noaa.gov/images/mpx/skywarn_map.jpg

There are quite a few more Skywarn repeaters on the map that are not on my list. The map is pretty good.

73 de NG0R