MT magazine UHF Satcom antenna project

[prcguy]

Howdy Skip,
Can you post a pic of your T adapter? The dimensions of the cables and T are somewhat critical so you should stick with the recommended parts.

I'm probably within a few miles of you (in San Pedro), I can take a look at your X-wing and compare to the one in the MT article to see if yours is working ok.
prcguy

"A splitter will not work, it must be a Tee adapter. I've had good success with L-Com and here is a link to a page with the F Tee and male F to SO239"


Hello all! I put together one of the X wing antennas included the 4' X 4' reflectors. While my "F" T adapter looks like a T, versus a normal splitter (input on top and two outputs on the bottom, and typically 3 DB loss) it does indicate two outputs and one input on the face of it. Is this a true "T" adaptor, or is it actually a splitter in a physical "T" hardware package? I can hear the data channel on 250.55, but not very loud. I put together a double rhombic antenna and it works well!

Any ideas? I am right on the beach in Los Angeles. By the way, I hear the pirates (255.550) on the Rhombic at about 180 degrees south of me. The data channel (@50.550 is to the west of me by quiet a bit.

73's


Skip

 

[strandbiker1]

F "T Connector

Howdy Skip,
Can you post a pic of your T adapter? The dimensions of the cables and T are somewhat critical so you should stick with the recommended parts.

I'm probably within a few miles of you (in San Pedro), I can take a look at your X-wing and compare to the one in the MT article to see if yours is working ok.
prcguy

Here you go! Now that I look at it, it seems to be a splitter rather than a real "T".

 

[strandbiker1]

More X Wing pictures

Here are two more pictures of the top and bottom of the wing

 

[prcguy]

Yup, that's a splitter and will add loss and mess up the circular polarity. I have a bunch of the recommended T adapters if you need one.

Nice work on the construction!
prcguy

 

[strandbiker1]

Yes I need one! I was going to check Fry's this AM!

Skip

 

[vansigint98661]

Can someone tell me which two issues that project appeared in please? I know I set them asside to do over the winter, but cannot find them now. I fear I might have to order reprints.

 

[strandbiker1]

If you go to page one or two of this thread, someone uploaded both parts

 

[OCO]

Check post #11 on first page of this thread... PDF's of both parts of the article..

Strandbiker -you're faster.. I was still reading both articles...

 

[strandbiker1]

I had already read all then 6 page and just remembered the links! No problem!


Skip

 

[strandbiker1]

I did not find a "T" F adapter at Fry's, so I found a "T" BNC adapter. I have "BNC" to "F" or "UHF" adapters so I can try them. I know it will add some minor length in the phasing harness, but I will try it!! Here is a picture of the completed harness.

PRC, I will take you up on your "F" T type adapter!

73's


Skip

 

[strandbiker1]

Okay, here is a picture of the completed unit on the roof of my 3 story house. It has a clear southern view with no obstructions. I can hear the data channel at 250.550, but it is weak. The pirates are a bit stronger on 255.550, but only a few are easily audible. I may need to replace the BNC "T" adapter with a "F" version, as it probably will be closer to PRC Guy's phasing harness dimensions. The harness is cut per the article dimensions assuming using the "F" T adapter. My use of the BNC "T" adapter and the additional dimensions due to the use of a BNC to "F" adapter has probably added some length. It will be interesting to see how the assembly works using the proper "F" T adapter. I played with the length of the 3" tube from the reflector screen and the X wing elements. Best reception was at 20 inches. I am using a Bearcat 780 XLT receiver. If necessary, I also can use a Yaesu FT 7800 transceiver or a Radio Shack Pro 97 handheld.

73's Skip

 

[strandbiker1]

Update

Ok with some great help from Mike, and some replacement parts, I am up and running with my X wing. Works great. I am listening to the pirates on 255.550 MHz, using my Yaesu FT 7800 VHF/UHF transceiver. I want to scan the 25 KHz channels using my Uniden 780 XLT receiver. Does anyone have a channel data file that I can upload to the receiver?

I also can hear the pirates and beacons well on my Yaesu FT 60 handheld transceiver!

Thanks again Mike!

Skip

 

[prcguy]

Skip,
Very nice meeting you and glad I could help out, great workmanship on the antenna!

I was thinking of a test to perform to see if your phasing harness is dialed in and there is a very easy way to do this without any test equipment.

We know the approximate worst case degradation on this antenna will be about 3dB going from circular pol to dual linear pol if the harness lengths are not optimal. Not easy or fun to measure minute changes like this while swapping different length cables.

However, if you swap the harness at the dipole connectors the antenna becomes LHCP and if the harness is dialed in you should have a good cross pol isolation of maybe 20dB or more at the sweet spot.

We could measure that on my analyzer with the preamp since the S/N on 250.350 was real good but you can do this at home using 250.350 or some other strong constant carrier. If the phasing harness is really dialed in, reception should go away completely with the cables swapped and without a preamp.
prcguy

Ok with some great help from Mike, and some replacement parts, I am up and running with my X wing. Works great. I am listening to the pirates on 255.550 MHz, using my Yaesu FT 7800 VHF/UHF transceiver. I want to scan the 25 KHz channels using my Uniden 780 XLT receiver. Does anyone have a channel data file that I can upload to the receiver?

I also can hear the pirates and beacons well on my Yaesu FT 60 handheld transceiver!

Thanks again Mike!

Skip

 

[strandbiker1]

Mike:

I will try the longer cable u made up and let you know what I find out. I stopped by Torrance Electronics today and picked up 4 more "F" chassis connectors. They did not have the "F" T connector that was used in the project. Signal Electronics did not have it either. Any idea where you got them?

73's


Skip

 

[prcguy]

The F Tees used in the article are from L-Com.

Coaxial T Adapter, F Female / Female / Female - BA132
prcguy

Mike:

I will try the longer cable u made up and let you know what I find out. I stopped by Torrance Electronics today and picked up 4 more "F" chassis connectors. They did not have the "F" T connector that was used in the project. Signal Electronics did not have it either. Any idea where you got them?

73's


Skip

 

[strandbiker1]

Great, thank you!

 

[KJ4ODU]

Have not even started on mine. but have found a Great deal on Ebay, mine coming from China, but $3.90 for 5 T connector.

F type Triple Female F/F/F TV Connector T-Adapter x5 | eBay

 

[Romak3]

Cables, Connectors & Patch Cables since 1995 have everything needed for this project connector wise.

 

[buds]

Hi, I am going to attempt to build this antenna. The main satcom sat here in Australia is the optus c1 which is a 45 degree look angle which should be great with this antenna.
I found some flat alum at work but its 40mm wide, which is just 2mm over one and a half inch. Would this screw everything up?? I could sand it down i suppose. Its also 1/8th an inch thick which should be all-right.

Cannot get the Tee adapter from anywhere here might have to get it from us.

 

[strandbiker1]

That should work. The big thing I found is make certain to use a "T" F adapter and not a splitter and watch your construction techniques! Enjoy yourself!