[amsat-bb] Re: M2 Xyagi sat 2 meter antenna

MM ka1rrw at yahoo.com
Thu May 28 07:55:51 PDT 2009

Hi Norman:
I used KLM with a polarity switch many years ago.
The polarity switch seemed unreliable and lossy, and I often forgot to change polarity on Leo’s.
When I replaced my KLM with M2, I decided not to bother with switching polarity and just run RHCP.

The benefits:
No switch losses, more gain.
Do not need to worry about forgetting to hit the polarity switch.
Transmitter power not limted to switch.

Other Tips:
Go with the most elements you can afford for a single boom.
	20+ elements on 2-meters
	40+ elements on 440

You can now get Flexible thick coax that will support an antenna Rotor.
Most people used RG-8 style coax, which is approximately 10 mm in diameter.
However you can now get flexible rotor grade coax which is approximately 15 mm in diameter, and has much lower loss than the best RG-8 style coax.

Belden RG-213
145 MHz	2.5 dB loss per 100 feet
438 MHz	4.5 dB loss per 100 feet

LMR 600 UltraFlex Rotor cable
145 MHz	1.1 dB loss per 100 feet
438 MHz	2.0 dB loss per 100 feet

As you can see, by switching from 10mm coax to 15mm coax you can reduce you loss by over 50%.  The 15mm cables cost 2-3 times as much, however you will not have to worry about coax losses any more on Frequencies below 2 gig.

73 wf1f

--- On Wed, 5/27/09, Norman W Osborne <ve3cje at gmail.com> wrote:

> From: Norman W Osborne <ve3cje at gmail.com>
> Subject: [amsat-bb]  M2 Xyagi sat 2 meter antenna
> To: "amsat-bb" <AMSAT-BB at amsat.org>
> Date: Wednesday, May 27, 2009, 1:41 PM
> Hi Everyone,
> Anyone out there using m2 Xyagi sat antenna with
> switching?
> Would like to hear your comments.
> I have settled on the gulf alpha for 70cm but I am looking
> for more gain
> for 2 meters.
> 73,
> Norman.
> _______________________________________________
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