[Boatanchors] antenna question
rayfrijr at msn.com
Thu Jan 16 18:44:04 EST 2014
Made it through fine Glen. thanks.
One final theory question about antennas and baluns that I have for now.
I have as part of my glow in the dark collection of radios a couple of the heathkit B-1 baluns.
I wouldnt do it because of the bulkiness, but I'm curious about the theory. Heathkit said the baluns can
be wired in 4:1 configuration to match 300 ohm feedline. In fact, my Elmer from my Novice days in the 60s
used one of them to connect to his folded dipoles made of TV twinlead. Would the B-1 not work above 10 meters
because of the coil dimensions or would there be some other reason? Heath only recommended them for 80-10,
and not even down to 160 meters.
Date: Thu, 16 Jan 2014 14:59:01 -0800
From: gzook at yahoo.com
Subject: Re: [Boatanchors] antenna question
To: rayfrijr at msn.com; jack at n7oo.com; boatanchors at puck.nether.net
A 4:1 balun is going to be needed. However, you can make one from a piece of coaxial cable for less than $1.00. That is what I have on both yagis with folded dipole driven elements to match the 200-ohms balanced to 50-ohms unbalanced.
I can't remember if attachments make it through on this reflector! However, attached is a diagram showing a 4:1
coaxial balun using 50-ohm coaxial cable for a 200-ohm to 50-ohm match. You can use RG58/U, RG213/U, RG214/U, RG8X, RG8/U, etc. To match 300-ohms to 75-ohms, use 75-ohm cable (RG59/U, RG-11/U, RG6/U, etc.) Glen, K9STH
On Thursday, January 16, 2014 2:57 PM, RAY FRIESS <rayfrijr at msn.com> wrote:
a folded dipole will need a 4:1 balun for feeding with coax ... or just straight coax feed?Date: Thu, 16 Jan 2014 12:43:25 -0800From: gzook at yahoo.comSubject: Re: [Boatanchors] antenna questionTo: jack at n7oo.com; rayfrijr at msn.com; boatanchors at puck.nether.netOO:The entire driven element.ITZ:My 2-meter yagi started out as a Cush-Craft and the gamma match got into very poor condition. I replaced the driven element with a folded dipole with the 2:1 rod diameter ratio. My 222 MHz yagi
still has the original gamma match. Basically, the type of match used on the driven element really doesn't matter.I obtained my 6-meter beam, along with other things, and there was no indication of the manufacturer. It resembled the Cush-Craft but there were a few things different. The driven element was in very poor condition and the gamma match was in even worse condition. Glen, K9STHWebsite:
http://k9sth.com On Thursday, January 16, 2014 12:43 PM, Jack Taylor <jack at n7oo.com> wrote: Glen, which horizontal element are you referring to, the gamma rod or the DE?Jack - n7oo-----Original Message----- From: RAY FRIESSSent: Thursday, January 16, 2014 11:15 AMTo: Glen
Zook ; BoatAnchorsSubject: Re: [Boatanchors] antenna questionActually, I
misspoke... My two meter antenna is the Cushcraft just like yours. Two 11 element phased. I have themvertically mounted and phased for FM. It's the driven elements on them that are gamma matched and kind of incrummy shape. I thought instead of rebuilding the gamma matches, I'd just build a different kind of driven elementthat can be attached to the boom, or a type that I can insulate from the boom with a small plastic block mounted to the boom itself.Date: Thu, 16 Jan 2014 10:03:54 -0800From: gzook at yahoo.comSubject: Re: antenna questionTo: rayfrijr at msn.com;
boatanchors at puck.nether.netGenerally, the type of match on the driven element doesn't matter.On both my 6-meter yagi and 2-meter yagi, I have changed the driven element to a folded dipole. This was done because I was having problems with the gamma match on both antennas.If you make one of the horizontal sections half the diameter of the other, the impedance will be close to 200-ohms instead of the 300-ohms when both sections are the same diameter. Then, matching to 50-ohm coaxial cable only requires a simple coaxial cable balun.My 6-meter yagi and my 2-meter yagi can be seen in the second photo at:http://k9sth.com/uploads/Antennas_At_K9STH.pdf Glen, K9STHWebsite: http://k9sth.com On Thursday, January 16, 2014 11:03 AM, RAY FRIESS <rayfrijr at msn.com> wrote: First of all ... let me take a moment to express sadness at the loss of Glen's fellow author, Glen W6ISQ. While he was not a "technical" author like Glen, it was always a real joy to read his stuff, just like it was to read Glen's stuff in the magazines.Now .. I have an antenna technical question.I have a
HyGain 11 element two meter beam that uses gamma matching.
The question I have is, does the type of drivenelement matter on a given beam as long as the driven element is adjusted for the best match at a given frequency?In other words, I am refurbishing the beam and have given some thought to redoing the driven element and usinga dipole, folded dipole or hairpin, or a Y match driven element.Ray WA7ITZ_______________________________________________Boatanchors mailing listBoatanchors at puck.nether.nethttps://puck.nether.net/mailman/listinfo/boatanchors-----No virus found in this message.Checked by AVG - www.avg.comVersion: 2012.0.2247 / Virus Database: 3681/6508 - Release Date: 01/16/14
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