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W1VT

Joined: Sat, Apr 4th 1998, 00:00 Roles: N/A Moderates: N/A

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Topic Created Posts Views Last Activity
QST Downloads Feb 19th 2016, 16:34 3 3,177 on 19/3/18
March 2016 QST Compact Multiband Dipole Feb 19th 2016, 15:23 1 2,061 on 19/2/16
Antenna analyzer vs feedline type Sep 21st 2012, 14:37 1 3,818 on 21/9/12
USB to Serial Port problems--Prolific Drivers Aug 3rd 2012, 18:27 2 4,556 on 26/12/15
Italian Phishing emails! Dec 13th 2011, 14:20 1 3,416 on 13/12/11
John K0GMO needs help designing SS Amp Nov 17th 2011, 15:53 1 3,339 on 17/11/11
1 Farad Capacitor to Eliminate Headlight Flicker? Oct 19th 2011, 13:14 4 5,097 on 9/11/11
History of Relay Rack Dimensions? Oct 17th 2011, 12:58 2 3,459 on 25/10/11
Miswired Selsyn Oct 13th 2011, 17:51 1 3,522 on 13/10/11
Stealth Antenna wire Sep 12th 2011, 12:51 2 4,132 on 13/9/11

Latest Posts

Topic Author Posted On
broomstick antenna parameters henryrichter 4 days, 11 hours ago
Ideally, you would attach a high impedance preamplifier to the base of the antenna. This would allow excellent signal transfer even without the expense of a tuner. You may want to study "Active Antennas," originally invented by R W Burhans to better understand this concept.

If you add a length of coax, the capacitance of the coax will shunt a significant amount of signal if the antenna has a high impedance, and a negligible amount when the impedance is low. The need to tune an antenna to resonance may be considered by some users to be an unnecessary hassle. Portable shortwave receivers often come with untuned whip antennas connected directly to a high impedance preamplifier.

Zak Lau W1VT
ARRL Senior Lab Engineer
Power Line noise - cold temperatures W5FN 1 week ago
The ultrasonic dish is too narrow to identify particular pole. A 400MHz Yagi and AM receiver is typically used to locate the pole. The dish is then used to locate the hardware on the pole. Some VHF handhelds have wideband AM receivers that can be used for direction finding, while others are FM only and not really useful.

Zak W1VT
ARRL Senior Lab Engineer
AA4PB Audio Interface: Any advice? NV2K 1 week, 5 days ago
http://www.arrl.org/arrl-periodicals-archive-search
Balun for Doublet Antenna N8EUI 1 week, 6 days ago
http://www.karinya.net/g3txq/tuner_balun/
study of the best balun to use

A 130 ft center fed dipole fed with 100 feet of 450 ohm window line and a 1:1 current balun is one of the better known combinations.

W5DXP has a downloadable spreadsheet if you would like to know good combinations of dipole and ladder line length for different bands.

http://www.w5dxp.com/goodbad/goodbad.htm

Zak W1VT
ARRL Senior Lab Engineer
Un identified signal 2 weeks ago
It may help to listen on a battery powered radio and shut of the main AC breaker to the house. Often the source is inside. Switching individual breakers can localize the source if it is inside.

Zak W1VT
ARRL Senior Lab Engineer

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