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
Coax: 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.
Example: 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 [email protected] wrote:
From: Norman W Osborne [email protected] Subject: [amsat-bb] M2 Xyagi sat 2 meter antenna To: "amsat-bb" [email protected] 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. _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb