[amsat-bb] Almost There

Joel Black w4jbb at charter.net
Sat Jan 4 16:42:58 PST 2014

After a rocky start to my Christmas Vacation (I fell off a ladder while 
pruning limbs from a tree - nothing broken, just banged up and bruised), 
I almost have my satellite station back on the air.

After doing some selling and horse-trading, I am back in possession of 
my FT-847 that I sold to my dad.

After cleaning out my storage building, I found a couple of fairly long 
runs of LMR400UF. I need to measure them, but I think it is more than 
enough to get me outside and up the mast.

I also have a U-100 control box thanks to someone on the list.

I operate an iMac with Mac OS X 10.9.1 so, for now, I am using SatPC32 
on my virtual machine. I have played around with MacDopplerPro, but it 
locks up on my computer continuously. I don't know if it has something 
to do with the USB-to-serial converter (I *do* have a null modem cable 
between the USB-to-serial converter and the FT-847), or if MDP is just 
limited in the unregistered version. The USB adapter works fine with my K3.

Let me ask a question about the Arrow Antenna. Someone mentioned Elk 
Antennas and, while I'm sure it's a fine product, I am already in 
possession of the Arrow. I've done a lot of reading and without getting 
into the arguments about Arrow vs. Elk and length of elements, etc., 
element isolation, and published vs. unpublished gain amounts let me 
tell you what I'm thinking:

First, I'm going to eliminate the diplexer. I will not need it for one 
thing. For another, it's limited to 10 W max input. From what I have 
read, my gain will be increased quite a bit. I don't remember the exact 
amount, but it's quite dramatic.

Second, the feed on the Arrow is a gamma match. From my reading, and I'm 
no engineer, for a gamma match to work properly the element(s) (at least 
the driven element) needs to be grounded. That's fine and, again, I 
don't want to get into the "why's" I just want to make sure I'm correct. 
Therefore, my question is:

Is there any reason I cannot turn the driven element 90 degrees to allow 
for a better connection to the BNC connector? Maybe not even 90 degrees, 
but enough to get to the BNC connector without the male connector on the 
cable touching the boom. I want to weatherproof those connections. What 
I'd like to do after I turn the gamma match is feed it with a very short 
length of LMR240 and then into a preamp. After the preamp, I'll have the 
LMR400UF to run to the FT-847. Most gamma matches I see on commercial 
antennas are on the side of the antenna - if horizontal, they're below 
(or above) the boom; if vertical, it's off to one side. The Arrow is the 
only antenna I've seen with a gamma match on which the gamma match is 
not to one side or the other of the boom. I hope I'm making sense.

Anyway, I wanted to let those folks who helped out know that I 
appreciate it and that I'm much closer to being back on the birds than I 
was a few weeks ago.

Joel - W4JBB

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