ARRL

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 1,179 on 21/9/12
USB to Serial Port problems--Prolific Drivers Aug 3rd 2012, 18:27 1 1,440 on 3/8/12
Italian Phishing emails! Dec 13th 2011, 14:20 1 1,260 on 13/12/11
John K0GMO needs help designing SS Amp Nov 17th 2011, 15:53 1 1,138 on 17/11/11
1 Farad Capacitor to Eliminate Headlight Flicker? Oct 19th 2011, 13:14 4 1,981 on 9/11/11
History of Relay Rack Dimensions? Oct 17th 2011, 12:58 2 1,358 on 25/10/11
Miswired Selsyn Oct 13th 2011, 17:51 1 1,204 on 13/10/11
Stealth Antenna wire Sep 12th 2011, 12:51 2 1,745 on 13/9/11
Designing a ham bench Aug 29th 2011, 12:38 2 1,819 on 29/8/11
Can't find recent Hint and Kink Aug 26th 2011, 13:01 1 1,739 on 26/8/11

Latest Posts

Topic Author Posted On
random wire antenna WD9DMM 1 day, 3 hours ago
http://www.w8ji.com/house_ground_layouts.htm

I'd suggest studying this page to choose the best way to bond your station ground to the service entrance. For lightning protection, you want a quick land easy path for lightning from your service entrance to the shack ground.

Zack W1VT
ARRL Senior Lab Engineer
psk31 with HRD(DM780) and IC7410 KR4YD 1 day, 12 hours ago

You are almost there.
You are missing the audio from the computer to the radio.

You may need to adjust a volume control on the computer.

Alternately, there may be a problem with the cable and/or interface between the computer and the radio.

It could also be that the default audio output device selected by the computer is wrong--you may need to choose the audio output device connected to the radio.

Zack Lau W1VT
ARRL Senior Lab Engineer

HF Beam Antenna Polarization WA9WVX 1 day, 14 hours ago

The advantage of horizontal polarization is that you get the benefit of ground gain--it is really hard to build a vertical beam with as much gain as a horizontal polarized beam. There certainly can be elevation angle advantages to vertical beams, but to some degree this is offset by the precise aiming capability afforded by the conventional Yagi/Tower. Being able to drop a noise source into a pattern null is a distinct advantage of a conventional beam.

Now that SDR receivers are becoming more common, it may make sense to connect an array of linear antennas to separate receivers and combine them with digital signal processing to optimize the polarization.

Zack Lau W1VT
ARRL Senior Lab Engineer
Dipole or loop? KO0Y 2 days, 12 hours ago

You could easily lose half the power in the balun--typical baluns are designed for 200 ohms at the output, not 2000ohms. Ideally, you would use a balun optimized for 1.8 to 8MHz, rather than something that tries to cover the entire HF spectrum.

A good all-around compromise, given that you have a radial field already installed, is an inverted-L. The feedpoint impedance is roughly half that of a dipole of twice the length, plus a bit of ground loss. With an autotuner, you typically want to avoid multiples of resonant half wavelenths, to keep the impedance down and within the autotuner matching range.

http://www.g8jnj.net/usingautotuners.htm
If you are using a longer length of wire, perhaps as a Sloper or inverted ā€˜Lā€™ good lengths to choose are either 19.4, 22.8 or 34.3m long, as these avoid high impedances on most of the Amateur bands from 160 to 6m.


Zack Lau W1VT
ARRL Senior Lab Engineer
Dipole or loop? KO0Y 2 days, 13 hours ago

While a larger loop has more resonances in the HF spectrum, the resonances become more narrow, so I doubt the large loop will meet your SWR objective.

YT-100 specification Tunes 4 to 800 ohms. (16 to 150 on 6M)

This suggests using a 4:1 balun at the feedpoint of the dipole.
This isn't ideal--at low impedances the loss of a tuner tends to be much higher, but it may work well enough for your needs. Beware of SWR drift--this indicates that a lot of power is being lost in the balun--which is actually quite likely given the limitations of balun technology.

Zack W1VT

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