Getting rid of the diplexer will reduce the loss, but not improve the gain. The gain is dependent on the design of the antenna.
73, Jim KQ6EA
Adding a preamp at the antenna is always a good idea for satellite use.
On 01/05/2014 12:42 AM, Joel Black wrote:
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getting into the arguments about Arrow vs. Elk and length of elements, etc., element isolation, and published vs. unpublished gain amounts let me tell you what I'm thinking: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.
73, Joel - W4JBB _______________________________________________ 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