tag:blogger.com,1999:blog-31778585228680322182012-05-19T02:27:00.855-07:00Radio Frequency SchematicsFA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.comBlogger389125tag:blogger.com,1999:blog-3177858522868032218.post-53769314245694661642012-05-19T02:27:00.000-07:002012-05-19T02:27:00.917-07:002012-05-19T02:27:00.917-07:00

I found this an interesting read.http://sdrbuzz.com/forum/showthread.php?t=73

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-4880105275192592212012-05-17T13:49:00.000-07:002012-05-17T13:49:00.300-07:002012-05-17T13:49:00.300-07:00

This past weekend we had nice weather here in southern Minnesota....mostly sunny and temperatures around 70. I spent some time working on a new portable antenna and then using it on the air.I was looking for something simpler than my 20 Meter Crappie Pole Vee dipole. I decided to try a quarter wavelength vertical. The March 2010 issue of QST has a good article on ground systems for vertical HF

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-17423322051026051242012-05-10T06:06:00.000-07:002012-05-10T06:06:01.068-07:002012-05-10T06:06:01.068-07:00

For those wanting to see a pretty comprehensive list of SDR options as they stand today then this link is seriously worth following:http://f4dan.free.fr/sdr_eng.html

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-3053024518919210142012-05-07T01:12:00.000-07:002012-05-07T01:12:01.172-07:002012-05-07T01:12:01.172-07:00

Morning after... over the shreddies and visual check I realised as I had swapped FET from BS170 to 2N7000 having run out of one TO92 version (see http://www.jaycar.com.au/images_uploaded/2N7000.PDF for the two TO92 pin configurations) obvious error... I had connected one of the FET switches for mute backwards at the LPF input (shared with RX as forms half the BPF), anyway on TX instead of the

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-34116633350185737692012-05-06T12:59:00.000-07:002012-05-06T12:59:00.494-07:002012-05-06T12:59:00.494-07:00

I am trying to get the project rebuilt/boxed after reworking the PTO. Unfortunately tonight after 3 hours trying I cannot get the cw RX/TX mute to function as it did and the TX has some nasty spurs so I've bust it somehow, and as not boxed up yet got to face reality I am not going to make the deadline to get this to FDIM so will not be entering. It is my own fault I mixed the Dayton and

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-74021001114555538442012-05-04T00:46:00.000-07:002012-05-04T00:46:00.852-07:002012-05-04T00:46:00.852-07:00

I was asked this at a rally demo recently:>> I was talking to you at the Loch Erne (Enniskillen)Rally on the 11th April past.I would like to know:What SDR kits are out there to buildWhat would you recommend to start with and which one to work up too.Where can I get them from and how much are they ?> Any thing else that you think that I may need to know about kits and what software to use

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-23783818152166299862012-05-03T08:23:00.000-07:002012-05-03T08:23:00.326-07:002012-05-03T08:23:00.326-07:00

Further to my tests ages ago with PTO... http://rf.circuitlab.org/2012/01/pto-vfo.htmlHere I am again with the same test rig but with a different construction technique. Again I post the information here incase others are interested in trying out a PTO.I have fused a number of M5 nylon nuts together, super glued them and wound red electrical tape about them. Into this I can turn a M5 brass bolt.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-19371355600474934112012-05-02T15:21:00.000-07:002012-05-02T15:21:00.213-07:002012-05-02T15:21:00.213-07:00

Work continues....

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-71446725538847590892012-05-02T10:20:00.000-07:002012-05-02T10:20:00.578-07:002012-05-02T10:20:00.578-07:00

Just been asked to give a SDR/QRP talk at Cambridge and District ARC.As I am working in Cambridge again I expect to be local again for a while so this looks possible. No idea about dates yet.I suspect a talk/demo might be best.I'll have some of the Softrocks built with me and a handful of other qrp kits and builds.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-91533295790066400912012-05-02T10:14:00.000-07:002012-05-02T10:14:01.287-07:002012-05-02T10:14:01.287-07:00

Some photos herehttp://m1kta.ham-radio-op.net/m1kta/builds/K1/

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-63063683867425621712012-04-25T04:18:00.000-07:002012-05-01T21:29:58.036-07:002012-05-01T21:29:58.036-07:00

I write this as asked a few questions about my name on the Elecraft UK builders list.... http://www.elecraft.com/k2_builders.htmI don't get paid by them to build for anyone and I don't pay them to include me on the list.Exchange with one amateur from UK and I am building his K1 right now:> I hope you don't mind me asing... I wonder how much you charge for your services? I am just in the process

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-84218457091029896482012-04-22T10:38:00.000-07:002012-05-01T21:29:58.202-07:002012-05-01T21:29:58.202-07:00

I saw this and thought was hillarious (grabbed from here http://xkcd.com/730/ and http://xkcd.com/643/)In addition working a lot with Simon HB9DRV and SDR-RADIO.com building the MOBOKIT V4.3 for him to use.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-66168518977667120872012-04-19T22:19:00.000-07:002012-05-01T21:29:55.072-07:002012-05-01T21:29:55.072-07:00

This wireless FM transmitter is designed to use an input from another sound source and transmits on the commercial FM band. This low power fm radio transmitter it is actually quite powerful. The first stage is the oscillator, and is tuned with the variable capacitor. Select an unused frequency, and carefully adjust C3 until the background noise stops (you have to disable the FM receiver’s mute

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-30639294857634475122012-04-19T14:49:00.000-07:002012-05-01T21:29:55.328-07:002012-05-01T21:29:55.328-07:00

With the chassis and front panel drilled, punched and painted this project should start looking more like a kit. Everything is in hand, all I need to do is mount, wire and solder.I laid out the chassis and front panel so that eventually this amplifier will serve as an upper deck of a 70 watt CW transmitter. My 1934 transmitter will be the lower deck/driver.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-71663741681442929552012-04-19T14:35:00.000-07:002012-05-01T21:29:58.356-07:002012-05-01T21:29:58.356-07:00

Just a quick note to say that I've uploaded my dissertation to SourceForge. It is an open source, Java based SCADA package.SourceForge link is: https://sourceforge.net/projects/ocpscada/And the wiki link is: http://sourceforge.net/apps/mediawiki/ocpscada/More details will follow, I'm sick of typing by now - I just spent the day filling my wiki

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-35074821282855897102012-04-15T12:46:00.000-07:002012-04-15T12:46:00.039-07:002012-04-15T12:46:00.039-07:00

This is a conventional FM RF power amplifier design, using bipolar transistors in a tuned class C circuit. Thanks to the use of two stages, the amplifier can be driven to full power with less than 1 watt driving power, so that a large gain margin results in this FM transmitter. Bipolar VHF power transistors have a severe affinity for low frequency self- oscillation. To obtain stability in this

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-28484483382307492682012-04-15T12:00:00.000-07:002012-04-15T12:00:02.199-07:002012-04-15T12:00:02.199-07:00

Done a couple of rally table/stall demos of SDR radios and asked about which ones to get/buy/build... In addition to some notes on software for the softrock SDR radios from Tony Parks KB9YIG I'll document some notes and ad them to the blog shortly.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-38365080852427768782012-04-15T03:31:00.000-07:002012-04-15T03:31:00.194-07:002012-04-15T03:31:00.194-07:00

Just got back.Photos of the table showing the SDR demos I ran.I also managed some /P operation from the rally as MI1KTA/P into a 20m dipole and then on the trip back on two afternoons from the beach near Dublin as EI/M1KTA/P and managed several 2xqrp contacts. Worked qrp DX included RA1CW and 4X4FR.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-56788110128659933102012-04-13T06:10:00.000-07:002012-04-13T06:10:00.715-07:002012-04-13T06:10:00.715-07:00

With an early spring here in SE Minnesota I can start thinking about QRP again. One of my favorite local picnic table QRP spots here in Rochester is Essex Park. It has plenty of space, lots of trees with limbs about right for antenna supports and movable picnic tables. Take a look here for a video on my operating from Essex park. On Saturday I worked N1LU, Don in NH, and K1TG, Roger in CT. K1TG

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-33738815783235018022012-04-09T20:05:00.000-07:002012-04-09T20:05:00.135-07:002012-04-09T20:05:00.135-07:00

KFI AM 640

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-77814357225189298172012-04-05T12:26:00.000-07:002012-04-05T12:26:00.164-07:002012-04-05T12:26:00.164-07:00

Just getting the display of kits ready.Cannot bring the whole shack so in the box will be (everything I have soldered from kits):The web links are current and provide info on them, some not from vendor.HB-1A / Direct from BD4RG http://k1hah.net/HB-1A-MK-II.htmlPFR-3 / http://www.qrpkits.com/pfr3.htmlATS-3B / KD1JV http://kd1jv.qrpradio.com/ATS3B/ats3b.HTMMKARS80 & CW Adapter /G6ALU http://

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-3404570845871948552012-04-04T10:26:00.000-07:002012-04-04T10:26:00.042-07:002012-04-04T10:26:00.042-07:00

Just finished building and here is a short video of it working.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-37196514753187770732012-04-04T09:32:00.000-07:002012-04-04T09:32:00.954-07:002012-04-04T09:32:00.954-07:00

The final stage of construction.I built this for 80m and 40m and T3 and T4 are small and the windings tight.In both cases the bifilar Secondary(T3) and the bifilar Primary (T4) are wound first with the single wire winding being added last. You may find this a little easier.Now usually if this were a V6.2 or V6.3 I would have added a drop of heat sink compound to the PA transistors before adding

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-37319659772107875672012-04-04T08:21:00.000-07:002012-04-04T08:21:00.391-07:002012-04-04T08:21:00.391-07:00

This is 1 SMT Ic and 4 SMT C underneath and on top an additional transformer (T2) and inductor (L1), 9 resistors, 3 C and a couple transistors.I had to substitute in for one of the 220pF caps (C21)

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0tag:blogger.com,1999:blog-3177858522868032218.post-85365050622958853092012-04-04T07:25:00.000-07:002012-04-04T07:25:00.646-07:002012-04-04T07:25:00.646-07:00

TopBottomThe TX op amps are two identical sets of components for the I & Q channels to create 0,90,180amd 270 degree inputs to the TX mixer, fed from a single 3.5mm stereo socket.

FA Mahananihttp://www.blogger.com/profile/08516331622397293778noreply@blogger.com0