SWR Protection Circuit

This scheme is an SWR meter, which is quite simple and easily built. Once you make a directional coupler, the results will be displayed with the measure led meters as a ratio SWR.

IC used in the scheme SWR meter is an LM3914, which are available on the market. Use non-inductive resistor (carbon-film or metal-oxide).

Complete set of SWR protection circuit schematic, see example image below to prototype soldering its components and the layout..

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SteelSeries Seberia V2 Headset Aiming the Gamers and Audiophiles Heads.

SteelSeries has released a pretty cool set of full size headphones called Siberia v2 and they have the heads of Gamers and audiophiles turning! Siberia v2 headphones feature 50mm speaker drivers, a retractable head band, the frequency range is 10 to 28,000 Hz and they are of 32 ohm impedance.

SteelSeries Siberia v2 incorporates an ‘invisible’ retractable 50-16,000 Hz microphone system (you can find it at the bottom of the left ear-cup) that you can use for VoIP chatting. The headphone has a good 2 meters extension cable and two 3.5mm jacks for audio and mic.

SteelSeries Siberia v2 headphone is released in two models, one with USB sound card while the other is just a plain model. Both have been available since November 2009.

At time of writing I am listening to these cans and find that they are very comfortable with the headband being self adjustable via self retracting wire cables. The leather ear pads are also very soft and pliable and there is no pinching or clamping feeling when wearing these cans. The sound is extremely dynamic and fast with details in full abundance but not over whelming or fatiguing. Bass is not constricted, it is well controlled and expansion is deep for these new cans right off the rack. Tonal balance, transient response and coherence for all ranges is extremely good.

The model I have is the plain version and not the USB version.

The nice part is the mike which can be completely concealed when not required. I am very pleasantly surprised by the overall quality and design of theses cans. The design is also extremely stylish and tasteful.

A set of cans that I do recommend for those die hard gamers/ head-fi'ers amongst you.

Retail pricing : $79.99 - $93.87

Of Interest:

SteelSeries Siberia v2 Headset Selected for the 52nd Annual GRAMMY® Awards Performers and Presenters Gift Bag

2012-01-26 16:57:03

- SteelSeries, a leading manufacturer of game peripherals and accessories, today announced that the SteelSeries Siberia V2 Headset has been selected to participate in the 52nd Annual GRAMMY® Awards official gift bag. As the headset of choice for both gamers and music lovers, the SteelSeries Siberia V2 Headset brings GRAMMY presenters and performer's superior sound and microphone technology in a stylish and comfortable design.

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AWA Linc Cundall Memorial OT CW Contest

For two days this past week I participated in the AWA Linc Cundall Memorial OT CW Contest. This contest gives a significant multiplier to those using pre 1947 gear. I used a National NC-101X and one of my recent homebrew transmitters, a "46 job". I worked nine stations in four states plus Ontario.

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Runsheng Disc Demagnetizer SH-2A

How does an aluminum disc magnetize? The inks used on the the disc label may contain materials that can pick up a magnetic charges as they are moved in and out of their case and the CD transport, and whilst spun at high speeds. The impact of this magnetization is very acute on older discs, which can be sonically rejuvenated with a Disc Demagnetizer. But even brand new CD's, DVD's, Blu-Ray, and other formats will benefit.

Each demagnetizing cycle takes about 8 seconds. After the first cycle, turn the disc over, and run the second cycle.

Originally developed by Japanese companies who marketed such products at a very high price, the Chinese made Runsheng SH-2A does the same job at 1/4 to 1/5 of the cost of Japanese products. I tried the cycles on a few of my favorite CD's and I immediately noticed they sounded cleaner, quieter, bass was tighter, mid and upper registers had sparkle and have luster.

The Chinese Runsheng SH-2A is retailing for US$62.00 and is a steal compared to the price of similar Japanese products. It is marketed in NA under a different name and also not at such a low price.

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USSR HAM-Radio CallBook in 1926

I just found a very interesting paper - a complete list of all transmitting amateur radio stations in 1926 in the USSR, club stations, as well as personal ones.
It is remarkable, that the frequencies and power levels of club stations are selected in such a way that ensures reliable traffic between distant regions and Moscow - the farther station from center, the higher its power and shorter its wavelength.
And another note - individuals had managed to use different wavelengths, so it was not too easy to contact each other that times.

READ MORE >>

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Power Supply with Over Voltage Protection 10A 13.8V

This power supply circuit will give 10 amps (12 amps surge) with performance that equals or exceeds any commercial unit. The circuit even has a current limiting feature which is a more reliable system than most commercial units have.

Just like other commercial units, this circuit uses the LM723 IC which gives us excellent voltage regulation. The circuit uses 3 pass transistors which must be heat sinked. Resistor R9 allows the fine tuning of the voltage to exactly 13.8 volts and the resistor network formed by resistors R4 through R7 controls the current limiting. The LM723 limits the current when the voltage drop across R5 approaches .7 volts. To reduce costs, most commercial units rely on the HFE of the pass transistors to determine the current limiting. The fault in that system is that the HFE of the pass transistors actually increases when the transistors heat up and risks a thermal runaway condition causing a possible failure of the pass transistors. Because this circuit samples the collector current of the pass transistors, thermal runaway is not a problem in this circuit making it a much more reliable power supply.

The only adjustment required is setting R9 to the desired output voltage of anywhere between 10 and 14 volts. You may use a front panel mounted 1K potentiometer for this purpose if desired. Resistor R1 only enhances temperature stability and can be eliminated if desired by connecting pins 5 and 6 of IC-1 together. Although it really isn't needed due to the type of current limiting circuit used, over voltage protection can be added to the circuit by connecting the circuit of Figure 2 to Vout. The only way over voltage could occur is if transistors Q2 or Q3 were to fail with a collector to emitter short. Although collector to emitter shorts do happen, it is more much more likely that the transistors will open up when they fail. I actually tested this and purposely destroyed several 2N3055's by shorting the emitters to ground. In all cases the transistors opened up and no collector to emitter short occurred in any transistor. In any event, the optional circuit in Figure 2 will give you that extra peace of mind when a very expensive radio is used with the power supply.

The circuit in Figure 2 senses when the voltage exceeds 15 volts and causes the zener diode to conduct. When the zener diode conducts, the gate of the SCR is turned on and causes the SCR to short which blows the 15 amp fuse and shuts off the output voltage. A 2N6399 was used for the SCR in the prototype but any suitable SCR can be used. While over voltage protection is a good idea, it should not be considered a substitute for large heat sinks. I personally feel the best protection from over voltage is the use of large heat sinks and a reliable current limiting circuit. Be sure to use large heat sinks along with heat sink grease for the 2N3055 transistors.

You will used this power supply on all kinds of transceivers from HF, VHF to UHF with excellent results and absolutely no hum. This power supply will be a welcome addition to your shack and will greatly enhance your knowledge of power supplies. Check out 2 Transistors Voice Transmitter

Check this out Build A 10 Amp 13.8 Volt Power Supply

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New VFO Spinner Knob - IC-R71E.

Today I replaced somewhat scratched old VFO spinner knob on the Icom IC-R71E with a new VFO Spinner knob rescued from a defective Kenwood TS-440 that was written off. The rubber trim around the side is better then the original Icom knob for tuning. Here are a couple of photos:

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Photo QSL Cards

QSL cards are a ham radio tradition that I was introduced to when I was a novice in 1966. My novice card then was a fairly generic design ordered 100 cards at a time from the Little Print Shop near Austin, Texas.

These days I usually custom create my QSL cards to go with a particular event or location. Lots of places will print digital photos and most allow on-line submission. I've seen prices as low as 9 cents per print with no minimum. All that is needed is a jpg file the right size.

Start with your favorite graphics editor, even Microsoft Paint has enough power and function to do the job.

First create a blank colored background with the right aspect ratio to match the prints to be ordered. I planned to order 4" x 6" prints so I created a 800 x 1200 pixel background. This background gives you control over auto resize/crop that occurs when your file is printed. The color doesn't matter. It will eventually get trimmed off.

Use your editor to cut out from the middle of the background a rectangle the matches the final size of the QSL card. For a typical 3.5" x 5.5" QSL card on a 800 x 1200 pixel background this rectangle will be 700 x 1050 pixels. This space is where you create your QSL card.

Use your graphics editor to add whatever QSL card text and images you wish. For Microsoft Paint I found it best to crop and resize any photos or images before I paste them into the QSL card.

Send the jpg file off to be printed.

The resulting 4" x 6" print will have a colored frame that needs to be trimmed off. This should leave your 3.5" x 5.5" QSL card. A paper cutter works great for trimming.

Other cheaper options may be available but for the QSL card information I use a Avery #5264 3.25" x 4" shipping label stuck to the back of the QSL card. Inside the Avery box are instructions telling how to use a template included in Microsoft Word to create six preprinted labels per sheet of shipping labels.

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My New Year's Resolutions, 2010

It's hard to improve upon perfection, but there are a few things I want to do to improve about myself:

1. Get more exercise (> 3x a week)
2. Get over 70% in all my modules
3. Start a personal website with one of the many domain names
4. Expand my friend group
5. Take up a sport
6. Get good at CoD:MW2 online
7. ...
8. Make 3 more resolutions ;)
   

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