Sorry - sent to the wrong address last time. I will also mention - "
represents inches - ' represents feet
----- Original Message -----
From: "NØATH" <firstname.lastname@example.org>
To: "Hsu, Aaron (NBC Universal)" <email@example.com>
Sent: Friday, May 19, 2006 11:51 PM
Subject: Re: [TowerTalk] The simple Gamma Match?
> Hey Folks - I am not trying to correct anyone but I feel like that gamma
> is more likely in feet than inches - I would think a gamma at 7 inches
> on a 15 meter beam would be a wee bit short. Not to sure - just seems
> like it
> Dave / NØATH
> ----- Original Message -----
> From: "Hsu, Aaron (NBC Universal)" <firstname.lastname@example.org>
> To: "I>TowerTalk" <email@example.com>
> Sent: Thursday, May 18, 2006 2:01 PM
> Subject: Re: [TowerTalk] The simple Gamma Match?
>> Hi Dino,
>> Realize that you're looking for more technical data on building a gamma
>> match from the materials you have, but I found this via Google...
>> Scroll down to the "for the experimenter" section (or do an in-page
>> search for the word "gamma") and you'll find a link to a simple Windows
>> app that VE3SQB wrote. Using this app with a target freq of 21.225MHz
>> (center of 15M), I got the following info:
>> Spacing: 4.759" (from driven element, center to center)
>> Gamma tube length: 7.276" (outer tube)
>> Tap point: 31.904"
>> Insertion length: 5.654 (overlap of outer and inner tubing).
>> The app suggests that the gamma tube (outer tube) be 1/4 the driven
>> element size.
>> With these numbers, it looks like your assumption that the outer tube is
>> too long is correct - it should be cut down to 7.276". After
>> "assembling" the capacitor, the tap point will be near the end of the
>> inner tube. I wish there were a way to test this before doing the
>> actual cutting, but you may not have that option. How about cutting the
>> tubing in half (to about 9 inches) and trimming from there?
>> Also take a look at Tom's (W8JI) info about the gamma match and how
>> length and diameter affect the network.
>> Hopefully, both of these links will get you in the general ball park.
TowerTalk mailing list