A C-Pole Antenna for QRPxpeditions

I've finished yet one more version of my Crappie Pole antenna, this one based on KF2YN's ground independent vertical antenna (or C-Pole). See here and April 2004 QST, page 37, for more information. After trimming it a little it measures 1:1 at 14.060 MHz rising to 2.5:1 at 14.35MHz and 1.2:1 at 14.0MHz.I found the choke balun to be key to...

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ESSB: Transmitted Audio Quality on Single Side Band.

Transmitted Audio Quality: If you are a serious SSB operator like I am then you will pay close attention to the transmitted audo quality of your signal. Two black boxes that you basically use for HiFi SSB are the 8 Band EQ and the EQplus produced by Julius Jones, W2IHY. I have found that these two gadgets produce a transmitted audio that...

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Yaesu FT-920 HF Transceiver.

HF + 50 MHz ALL MODE TRANSCEIVERYaesu's engineers had dedicated themselves to the enhancement of Signal-To-Noise ratio in designing the FT-920. Since recovered audio is the most important consideration at both ends of the communication circuit, the FT-920 is particularly optimized for noise reduction, wide dynamic range consistent with excellent...

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Yaesu FL-2100B HF Linear Amplifier

This is the station Linear Amplifier, it is a Yaesu FL-2100B which operates in Class B grounded grid configuration using a pair of 572B tubes. Max. input power is 1,200 watts PEP.Additional box fan used for ventilation of heat placed on top of the FL-2100B: <span class="blsp-spelling-error" id="SPELLING_ERROR_2">Yaesu</span>...

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K1 build.

40m Pre-Mix Oscillator Signal Spectrum and PlotPin 4 J6 Filter board20m Pre-Mix Oscillator Signal Spectrum and PlotPin 4 J6 Filter boardAdjust the pre-mix filter using an oscilloscope and pin 6 on J6 filter board.(nice thing is same pin both bands) You realy need 4 hands to video this so apologies poor video.A signal at la...

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An SW-4 Mystery

A friend of mine noticed that my National SW-4 shown at http://www.prismnet.com/~nielw/nat_list/sw4.htm uses what looks like standard SW3 type audios as opposed to the National "Duo Coupler" mentioned in the SW-4 ad. Other National radios show a production process that used parts that were available. Close inspection and comparisons between...

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K1 build RF part II

90% of TX side done now, just got the PA transistors and the transformers to solder in (just in place mechanically for now) and then that should be it as far as melting solder is concerned. There was one missing 473 (0.047uF) cap (C50) I have substituted in something from my own supplies that should work until Elecraft send a replacement.The alignment for RX doesn't always seem to work for TX and the manual and notes say that...

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K1 build. Up to RF board Part I

Just finished the build of the K1 up to the end of the RF Board Part 1.Short video of the finished article.The current draw with the back light is 64mA.RX side all done and aligned. I used three signal sources, an FT817, a USB Si570 and a Colpitts Crystal oscillator using 2N3904 and 7.040MHz and 14.060 MHz so should be pretty true but the frequency can be amended through the menus. But once amended for 40m automatically the...

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A 20 Meter Crappie Pole Vertical

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...

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SDR list

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.h...

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ARCI 72 part challange - realised error

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 FET passing RF to the LPF instead...

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ARCI QRP 72 part challange - Going to miss it.

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 Friedrichshafen dates up so lost 5 weeks....

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What SDR kits are out there?

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...

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ARCI QRP 72 part challange - Update

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...

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More TZ-20 Amplifier

Work continues....

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SDR/QRP talk at Cambridge and District ARC

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 buil...

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K1 Build

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

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