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hams use coax to transfer high frequency electromagnetic energy between antennae and receivers and transmitters
Jan 19, 2009
(an archived page, this may contain outdated or broken links)
coax phasing diagram
I still get requests for this ..
This first appeared on my website in 2001.

sparkly tower
I will use my radios . . .
I will update my website . . .

I will use my radios . . .
I will update my website . . .


I will use my radios . . .
I will update my website . . .

hit-any-key

Back in the day, we really enjoyed Oscar13 ...


Once upon a time, in a not-so-distant memory,
I had built the satellite array of my dreams . . .
- and was using it regularly to QSO around the world using the AO-13 satellite.
former satellite antenna array
I had started accumulating the pieces before leaving Denver in 1990, and had it together as shown above in 1994. Shortly after this I added the ARR RF-sensing/switching preamps, installed just under the rotor in the pointy part of the tower. This was perched upon 30 feet of Rohn 25G, and was fed with a 9913-style air-dialectric coax made by International Wire & Cable (IWC-9086).  I had found a very rigid (1/4" wall) piece of fiberglass round tube that fit inside the Yaesu/Kenpro rotor, and painted it white to help fend off the UV it was sure to receive. Apparently Google never forgets some things, as I once had a diagram and description of these phasing cables on this website - and every now and then I get an email from someone asking if it is still available. Here is my original description to go with the diagram posted above.
(The cebik.com website in the original link requires a password now, but is a free registration.
This looks to be the most relevant link on the site as it is now :
http://www.cebik.com/content/a10/trans/quarter.html )


There are better places than this, that explain how this works . . .  So I won't.

  With my array, I had two KLM-14C for 145 MHz & two KLM-18C for 435 MHz.  The Yaesu/Kenpro rotator allowed a long boom, with one of each on either side.  I used RG-11 (75 Ohm) coax for the matching sections.  With a velocity factor of .66, the 2m sections were 2.25 wavelengths (9/4) or 360.6 cm (~11.8 ft) long.  The .7m sections were 3.25 wavelengths (13/4) or 174.8 cm (~5.7 ft) long.  This allowed for a little slack in adjusting the physical spacing between each side of the pairs.  I compared the 2m beam spacing at 1.05, 1.25, and 1.39 wavelength - and found lowest SWR at 1.25 wavelength (101 in).  The SWR for the 435 band was influenced by the 2m antennae spacing, but was generally lower and broader, the further apart they could go.  I settled for 2 wavelengths (54 in).

  Then bringing each pair together with a standard coax "tee" connector, I used 50 Ohm cable (9913) to make the rotor loops, and deliver to the tower mounted preamps.  For these relatively short pieces, I used multiples of half-wavelength, to ensure 50 Ohm.  For the 2m side, this was 1 wavelength (2/2) - 172.6 cm or about 5.6 ft.  The .7m piece was 3.5 wavelength (7/2) - 202.7 cm or about 6.6 ft.

I have since moved a few times, and sold/traded-off/given away most of that system.
Hopefully someday soon, we will again have such a wonderful satellite as was AO-13.
 - Just might have to build up another such antenna system when that comes about.
73 for now ...   /;^)
AO-13 project was managed by AMSAT Germany
AO-13 (Phase3C) was an International project
of AMSAT-DL and was launched in 1988.






Yaesu FT-736 drawing
AO-13 satellite
 
When All Else FailsHuntsville-Madison County EMA
The local ARES/RACES organizations are consolidating some of the overhead associated with registration and training of the membership. Join us on the 2nd Thursday evening of each month for a good meeting at the HMC EMA EOC (go to their new website and learn more about this).
Remember, the severe weather season is available year-round.
Check for current SKYWARN Spotter Classes.
Huntsville Hamfest - 2008
The Huntsville Hamfest is coming in August. Never too early to start planning.
I love home-made antennas . . .digital radio modemfailing process notification ?
Recent discoveries, rants and raves, and experiments :
+ Be sure to check www.somenet.net for interesting articles inbetween updates to this page.
+ An amazing software defined radio !!!  http://websdr.ewi.utwente.nl:8901/
+ UISS = really neat digital radio program by
ON6MU, see his website to download.
+ Orbitron = very sophisticated satellite tracking program by
Sebastian, see his website to download.
+ NBEMS = Narrow Band Emergency Messaging System - this works !!! (new Yahoo group)
+
VHF Propagation Map = using APRS beacons to visualize current propagation conditions.
+ APRS.FI = another view of the APRS-IS database, from
OH7LZB in Finland.
+ CWOP = My weather instruments are still active and logging.
although I'm not yet satisfied with the radiation shield I made for the external thermometer.
The reading is still too high in full sun. (check my reports via FindU).
eQSL.cc = I am actually getting some more of my old logs entered . . .
front porch sunrise QSL cardfront porch sunset QSL card
Previous pages from the archives :
+ 2008 . . .+ 2007 . . .
2006 . . .
+ 2005 . . .
Additional organizations, projects and web sites that I continue to support and promote :

Johnson City Amateur Radio AssociationAmateur Radio Emergency ServiceAmerican Radio Relay LeagueNWS Skywarn Spotter ProgramRadio Amateur Satelite Corporation
location of ISS
This generated image shows the current orbital position of the International Space Station . . .

Thanks to www.heavens-above.com for excellent tracking and visual observation schedules.



I really enjoy stepping outside to watch this beautiful machine fly over. Thanks to Chris Peat's excellent web site, we can know exactly when and where to watch for this and many other satellites.

Recently put in a real desk for my 'office'.
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RF laboratory
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