A word of caution - DC grounded antennas

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G7MRV
Posts: 3
Joined: Fri Feb 28, 2014 11:55 am

A word of caution - DC grounded antennas

Post by G7MRV » Thu Mar 06, 2014 4:27 pm

I will voice this caution now, although I have yet to establish if this is the exact cause -

My first R820T dongle seems to have failed after attempts to use it with an antenna with a hairpin impedance match - in otherwords, with an antenna that DC grounds the antenna connector.

I am trying to find from the datasheet if the R820T is sensitive to ground conditions on the antenna port, but I would advise anyone to avoid antennas that are DC grounded like this, at least for the time being!

It may be a simple overload failure though, and im trying to find this out. Luckily, I have a spare...

RadioMaintainer
Posts: 1
Joined: Fri May 02, 2014 11:54 am

Re: A word of caution - DC grounded antennas

Post by RadioMaintainer » Fri May 02, 2014 12:04 pm

Some RTL Sticks seem to support supplying voltage to an external device such as a pre-amp I have read 3+ on the antenna connector and on some as much as 5+. Before hooking your unit up to any external device I would check the antenna terminals to see if there is any voltage present. If there is it would be advisable to purchase an isolator such is used with inline cartridge pre-amps such as those sold for Satellite systems or antenna pre-amps like the cartridge remote pre-amps sold by Radio Shack that the preamp is to be installed at or near the antenna. These units are usually attached to the antenna side of the pre-amp and heat shrinked in place with clear shrink. They can be ordered on line from several satellite sources and are usually located near the bias "T" power injectors. It is their exact purpose to isolat DC and pass RF up to around 3 or 4 Ghz.
Laurin WB4IVG

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