Hello

I have the Maspro system in use here and i switch polarisation from RHCP to LHCP almost every pass, no matter which sat i'm working on, to get best sigs up and down. My homemade antennes are only RHCP, but i compared them with the Maspo system and changing pol gave big differences at my location.

The homemade cross yagis are made with elements spaced exactly 1/4 lambda, because it is easier then to make the feedlines. When spacings are less then 1/4 lambda, you need to use the difference in that spacing in the calculation for the exact lenght of the feedlines.(90°= 1/4 lamda spacing).I use 2 pieces of 75ohm to a T-connector, or you can use 50ohm to a 2port combiner.

Made crossyagis for 2m,70cm and 23cm...all working great, but like my Maspro WHS-32N system more because i have pol-switching on them.

73's

Jerry,ON4CJQ

----- Oorspronkelijk bericht ----- Van: "Chris Thompson" g0kla@arrl.net Aan: "Richard Tejera" Saguaroastro@cox.net Cc: "AMSAT" amsat-bb@amsat.org, "Tom Schuessler" tjschuessler@verizon.net Verzonden: Dinsdag 24 mei 2016 16:32:13 Onderwerp: Re: [amsat-bb] Cuscraft 416-TB and 22XB phasing harneses???

Tom,

I'm also setting up some antennae and have the elements mounted in the same position. My understanding it that to get Circular Polarization you need to feed one antennae quarter of a wavelength ahead of the other. The examples in the satellite handbook show the antennae physically mounted quarter of a wavelength apart. If the elements are in the same location then the feed line to one needs to be 1/4 wavelength shorter than to the other. Then it will be fed first and the signal will be 1/4 wavelength ahead of the other antenna. Note that the elements will actually be slightly offset and this difference should be taken into account in the feed line length.

The two feed lines should each be 50 ohm. You can then combine them with a standard combiner or use a coax T and two quarter wavelength sections of 75 ohm coax, one for each feed line, as a matching section.

I don't think it is worthwhile setting up the ability to switch from LHCP to RHCP or vice versa if the spacecraft has linear antennae, because the difference is only 3dB, but others may disagree. If the spacecraft has CP antennae then its very important to match the polarization. Good explanation here: http://www.pe0sat.vgnet.nl/antenna/polarization/

Chris

On Tue, May 24, 2016 at 1:30 AM, Richard Tejera Saguaroastro@cox.net wrote:

Tom,

I have a copy of the manual for this antenna. I'd be happy to scan it and send it to you. It may be of some help.

Rick Tejera K7TEJ Saguaro Astronomy Club www.SaguaroAstro.org Thunderbird Amateur Radio Club www.w7tbc.org

On May 23, 2016, at 20:32, Tom Schuessler tjschuessler@verizon.net wrote:

Hello all,

I recently acquired a pair of Cushcraft Satellite antennas, the 22XB and the 416-TB. Both are Cross fed dual polarity Yagis. What did not come with either of these antennas was the phasing harnesses that were a part of the original contents. The two meter 22XB is fed with crossed driven elements in the same location on the boom and SO239 connectors in place on the antenna. The 416-TB has direct connections from coax to the driven elements and also to the coax balun on each of the driven elements. The driven elements are offset fed so as to provide the natural delay in the one direction.

Cushcraft did sell a PS-4 which I believe was a relay controlled switch for the 435Mhz 416-TB but if they sold a 2 meter version, I cannot tell. I do have a contact at Cushcraft I was given that I will be reaching out to for more information

The "Satellite handbook" does have some description on how to configure a fixed harness for the two types of feed orientations. I am though confused to understand how to understand the direction of rotation but that is for another post.

Anyway, does anyone who used to have these antennas or something similar have phasing harnesses, either fixed or switchable that would work with them lying around? I would be interested in acquiring them from you.

Thanks and 73.

Tom Schuessler, N5HYP N5HYP@arrl.net

PS. I just picked up a used FT-847 so am looking forward to getting these antennas up in the air and seeing how they perform.

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Chris Thompson said (in part):

I don't think it is worthwhile setting up the ability to switch from

LHCP

to RHCP or vice versa if the spacecraft has linear antennae, because the difference is only 3dB, but others may disagree.

Chris, Add one more to disagree with you. I have crossed yagis on 2M and 430 that are used for both terrestrial and satellite. I can switch between polarities and sometimes it makes little difference, but on some passes, the difference is quite pronounced. When trying to dig out a really weak signal, even a few dB is quite helpful.

Jim - K6CCC Satellite inactive at the moment...