W1VT
| Joined: | Sat, Apr 4th 1998, 00:00 | Roles: | N/A | Moderates: | N/A |
Latest Topics
| Topic | Created | Posts | Views | Last Activity |
|---|---|---|---|---|
| Antenna analyzer vs feedline type | Sep 21st 2012, 14:37 | 1 | 942 | on 21/9/12 |
| USB to Serial Port problems--Prolific Drivers | Aug 3rd 2012, 18:27 | 1 | 1,131 | on 3/8/12 |
| Italian Phishing emails! | Dec 13th 2011, 14:20 | 1 | 1,098 | on 13/12/11 |
| John K0GMO needs help designing SS Amp | Nov 17th 2011, 15:53 | 1 | 974 | on 17/11/11 |
| 1 Farad Capacitor to Eliminate Headlight Flicker? | Oct 19th 2011, 13:14 | 4 | 1,730 | on 9/11/11 |
| History of Relay Rack Dimensions? | Oct 17th 2011, 12:58 | 2 | 1,203 | on 25/10/11 |
| Miswired Selsyn | Oct 13th 2011, 17:51 | 1 | 1,030 | on 13/10/11 |
| Stealth Antenna wire | Sep 12th 2011, 12:51 | 2 | 1,531 | on 13/9/11 |
| Designing a ham bench | Aug 29th 2011, 12:38 | 2 | 1,616 | on 29/8/11 |
| Can't find recent Hint and Kink | Aug 26th 2011, 13:01 | 1 | 1,474 | on 26/8/11 |
Latest Posts
| Topic | Author | Posted On |
|---|---|---|
| Icom IC-761 CAT/CIV Interface | KC9ZFI | 16 hours, 47 minutes ago |
| CT by K1EA was the first really popular contest logging program. http://www.k1ea.com/download/ See page 18 of the manual for one of the first computer interfaces for radios--you used a 25 pin serial port connected to a transistor that keyed the radio! Page 17 describes using a Parallel Port to control the PTT line to switch the radio between transmit and receive. These days, you might want to use a more modern USB device and avoid antiquated serial and parallel ports. Zack Lau W1VT ARRL Senior Lab Engineer |
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| Icom IC-761 CAT/CIV Interface | KC9ZFI | 20 hours, 41 minutes ago |
| The IC-761 is a 25 year old radio. The computer control is quite limited--see page 2 of the instruction manual for the short list. A quick search of the Internet suggests that T/R switching can be added with another interface... In short, for remote control, you will need to work very hard. The contemporaneous product reviews are quite confusing about remote control capabilities as remote control was something in the future for the folks that reviewed the radio back in 1988. Zack Lau W1VT ARRL Senior Lab Engineer |
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| Everyham's Amp | effirlem | 2 days, 21 hours ago |
| Figure 5 is a voltage doubler circuit. It is usually cheaper to use a voltage doubler circuit than to get a transformer that will allow you to use more conventional rectifier circuits when you need the high voltages required for amplifiers. The Heathkit SB-220 also uses a voltage doubler circuit, but with a special low resistance windings that allows the use of a full wave, rather than a half wave circuit. Voltage regulation will suffer if you try to use a full wave circuit with a typical transformer. Zack Lau W1VT ARRL Senior Lab Engineer |
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| Antenna for 10m contest | KC9ZFI | 2 days, 22 hours ago |
| Central Asia can be a difficult place to contact with just 100 watts and a simple antenna. From Indiana, you have a "Polar Path." Polar Paths are challenging for DXers--your signal is likely to be blocked by the auroral curtain. A K index of 3 or higher typically means no propagation. I'd be happy with just one or two contacts--just as I was in the EME contest, where I made two QSOs and got a great looking participation pin! http://www.voacap.com/ http://www.voacap.com/prediction.html I'd suggest running this propagation program for both Long and Short paths--you will find your propagation windows to be quite short. Yes, a Yagi is typically best, but on a path like this, where you want to work both long and short paths, a bidirectional wire beam may be better. A High Gain Single Wire Beam by Robert Wilson, AL7KK QST July 2009, pp 38-39 The author now recommends feeding this antenna directly with a 4:1 balun instead of the shunt inductor arrangement suggested in the article. http://www.arrl.org/files/file/protected/Group/Members/Technology/tis/info/pdf/QST_Jul_2009_p38-39.pdf On the East Coast, the difference between magnetic North and true North is almost 14 degrees, so we need to account for that when using a compass to set the beam heading. It is likely that you don't need to worry about that where you live. A good reference for North in much of the USA is Polaris, the pole star--though it doesn't work as well as you get closer to the equator. Zack Lau W1VT ARRL Senior Lab Engineer |
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| PSK31 Operation | KK4WVG | 1 week, 2 days ago |
| http://www.arrl.org/frequency-allocations 10 Meters Novice and Technician classes: 28.000-28.300 MHz: CW, RTTY/Data--Maximum power 200 watts PEP |
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