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Opinions on this rhombic, Timbo?

12.109.26.64
Posted on October 13, 2009 at 09:10:49
Travis
Audiophile

Posts: 3266
Location: La Grange, Texas
Joined: November 25, 2001
Contributor
  Since: May 13, 2008
 Just curious.


"If people don't want to come, nothing will stop them" - Sol Hurok
Well it's not really a rhombic for a start!, posted on October 13, 2009 at 12:53:57
Timbo in Oz
Audiophile

Posts: 11394
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 It's a vee antenna with a reflector added. It has just half the gain of a single wire rhombic cut for 88 mhz*. It also won't be as directional as a full rhombic.

*with 4 equal sides of 11.8 feet. That would have a gain of 6db at 88meg, and an increasing amount as you go up the band. But you can use twin ribbon and get 12db gain.

A 3 element FM only Yagi may well do better, and have a better pattern.

And we all know about advertised gain specs by now, don't we!?

A real rhombic looks like this <> in plan view -> being the axis.

Its only advantage is that it can be used with a rotator.

But if you have an attic or crawl space - which they mention!!! - and have only one or two truly worthwhile stations anyway, why not build your own using twin ribbon aka TV ribbon / 300 ohm cable, you'd then have two antennas in one, with more than 12db gain. Two if the stations are far apart, or a spread double.

One day soon one of the moderators here will get off their arse and offer that AA host the rhombic article from the now defunct 'Audio' magazine.

Then I wouldn't have to do it.

Until you have read the article you may not get how cheap a solution it is. Not in time and effort, no.

It does occur to me that my advocacy is having some kind of an impact. ;-)






Warmest

Timothy Bailey
The Skyptical Mensurer and Audio Scrounger

And gladly would he learn and gladly teach - Chaucer. ;-)!

'Still not saluting.'

http://www.theanalogdept.com/tim_bailey.htm
No question, you have made an impact, posted on November 3, 2009 at 09:36:28
rickmcinnis@dogwoodfabrics.com
Audiophile

Posts: 723
Location: Atlanta
Joined: December 15, 2003
 I was a recipient of the article. Though I was a subscriber to AUDIO when the article came out, and I remember pulling it out as something important it was lost, and I appreciate your archival efforts.

MY PROBLEM, is that I just cannot figure out how to start. There is lots of information there but not an easy starting point for us DIY'ers with very little understanding of antenna art.

Is there any way you would be willing to show us a good starting point and construction tips from your experience? I know I would be greatly appreciative of something to get me started.

Either way, we are in your debt.
Thanks, again,

Rick McInnis

Sorry to take so long to reply and I've decided to start a new thread so see above., posted on November 5, 2009 at 20:58:01
Timbo in Oz
Audiophile

Posts: 11394
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 :-)!


Warmest

Timothy Bailey
The Skyptical Mensurer and Audio Scrounger

And gladly would he learn and gladly teach - Chaucer. ;-)!

'Still not saluting.'

http://www.theanalogdept.com/tim_bailey.htm

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