[amsat-bb] Splitter for receiving system?
howied231 at hotmail.com
Fri Feb 6 15:30:19 UTC 2015
Hi Mark, no matter what you use you will lose 3 db + the splitter insertion loss. If you are putting the splitter after a LNA, then the added loss is usually not important. However, if you are putting the splitter directly between the antenna and your receiver the loss of the splitter will add directly to the receiver noise figure, which in weak signal work is the real difference between hearing and not hearing a signal.
If you can afford the 3+ dB increase in system noise figure, a plain old TV splitter is actually not bad. The outdoor variety are water tight, F-connectors are pretty good at UHF (in some ways better than a BNC). If it's RX only, RG-6 is low loss, inexpensive and the slight mis-match is not that significant.
If noise figure is important, a low gain, low noise figure amp before the splitter (which can be turned around and used as a combiner) is a good idea.
Mini-circuits are great components and have a great variety of quality RF/IF components. The only problem is that their distribution network is limited and unless you find a retail source that has what you want getting parts can be a little difficult .... and you will start getting called by the "area rep" wanting to know how many hundred you will be needing every few months :) That said, they HAVE been accomodating when I needed something that wasn't available through distribution.
- Howie, AB2S
> Date: Fri, 6 Feb 2015 08:00:04 -0500
> From: marklhammond at gmail.com
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] Splitter for receiving system?
> Hello All,
> I am really wishing for a "splitter" for my receiving system, good for both
> 2M and 70cm (so say, 144-450MHz or so.)
> Any suggestions? I really don't to lose 3dB in the process, but fear the
> only way to avoid that is some powered/amplified system. I recall such a
> device, but cannot for the life of me think where or the possible source.
> I do not need to xmit through it; receive only. Also, I do not need to
> pass 12V to power preamps, etc. So, just a low loss splitter good for 2M
> and 70cm. SMA, BNC, N connectors--any will work in my shack.
> Do folks refer to these as splitters? Combiners? Power splitters? I know
> about Mini Circuits--that's a sensory overload of stuff to pick through :)
> Any pointers to sources or such devices will be welcomed!
> Mark L. Hammond [N8MH]
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