henkvdw 0 Report post Posted July 29, 2009 I recently got a system similar to this: http://www.hczye.com/en/product_detail.asp?productid=422 Mine has a 1000 mW Tx that looks exactly the same as the 1500 mW unit in the link. I'd like to upgrade the Rx antenna with something like this: http://www.l-com.com/item.aspx?id=20248 When I started doing the research, I noticed that the connector on the L-com patch antenna is SMA (implying 50 Ohm impedance?). The specifications for this antenna indicates that it is good for video though. The antenna connector on the Rx is Type F (implying 75 Ohm impedance?). So it seems there is a mismatch here. Probably my limited knowledge of this subject is to blame. My understanding is that video gear uses 75 Ohm? I also noticed on my 900 MHz Rx (Racewood) the antenna connector is SMA. This confuses me more. Anybody able to clarify this for me? Thanks Henk Share this post Link to post Share on other sites
Mr.RC-Cam 123 Report post Posted July 29, 2009 The F-connectors are not good choices for 1.2GHz, but you will find them on low cost A/V systems because of the savings to the mfg. The satellite tuner modules found inside the 900-1.3GHz receivers typically have 75 ohm RF inputs, even when a SMA has been used. So, either way you end up with a 50ohm/75ohm situation. The minor mismatch is actually nothing serious to be concerned about. So, go ahead and use an RF adapter to convert the F-connector to SMA. Honestly, I'd recommend you rescale the GP Patch for use on your frequency. It works great. After all, you're on a DiY site, where building things is king. Share this post Link to post Share on other sites
