Enhance Your Easy Sat Experience!

December 7, 2012

Clayton, W5PFG, a very active satellite operator and grid activator, did a write-up on a very cheap and simple upgrade to your amateur satellite setup - one which will change your operating skills dramatically.  Below is his description of the upgrade:

Have you thought about upgrading your station to full-duplex capability?
 

I realize that many amateurs jump into the satellite fray by utilizing an existing handheld radio and an antenna like the Arrow, Elk, or tape-measure beam. It's a great way to get your feet wet and make that "first" contact via the birds.

Now, let's look at how we can do BETTER.

Full-duplex has a very important purpose in the satellite world. It allows you, the ground station, to know that your signal is being received and retransmitted by the satellite. I’m not saying it is a mandatory but once you see its benefit, you may never want to go “semi” again.

How do you really know you are being heard by the bird if you can't hear yourself? Answer: You don't.

How do you know another station wasn't already being captured by the bird and in the middle of a QSO when you transmit? Answer: You don't.

Let's talk about HOW to do full-duplex. First of all, you don't need base-station radios like the Icom IC-9100, IC-910, Kenwood TS-2000, or Yaesu FT-847. If you own two handhelds, chances are you have what you need!

What you need is at least one radio capable of transmitting on the uplink and one radio capable of receiving on the downlink. For example using AO-27:

1. A 2m-only HT, set to the satellite's uplink, ~145.85 MHz.
2. A 70cm-only HT, set to the satellite's downlink, ~436.795 MHz.

Technically you do not even need a radio capable of transmitting to hear yourself on the downlink. A scanner or pocket receiver works dandy!

To get into full-duplex inexpensively, there are numerous options. You can buy a NEW Baeofeng UV-3R for about $50-60 USD, shipped. This radio could serve as an uplink or downlink radio, depending on your need. I’m not peddling these radios but using them as an example.

If you have the Arrow with the built-in diplexer, simply bypass it by running a patch cord from each radio to the respective UHF and VHF beams. If you are running an Elk or tape-measure 2m beam, you will need an inexpensive diplexer to give you both 2m and 70cm feed points. One can be constructed easily or purchased from numerous vendors for $30-80.

Give full-duplex a try. You will not only help the satellite community by eliminating unnecessary hetero-dyning tug-of-war, it will generally make you sound better on the birds! Oh, and use a pair of earphones or a headset when you give it a try to avoid feedback.

Thanks & 73,
Clayton
W5PFG

Here are some more example full-duplex combinations:

Wouxon HT - Downlink
2m only-HT - Uplink

FT-60R - Uplink
Baofeng - Downlink

Handheld scanner - Downlink
Dual-band HT - Uplink