Erkal Taskin Posted October 30, 2015 Report Share Posted October 30, 2015 Wow you tested, thats very kind of you. So it always needs power. Thats good to know. Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted October 30, 2015 Report Share Posted October 30, 2015 While a lot of wireless theory is useful and makes sense it is not always what we experience in practice. I have tested 2 micplexer1s daisy chained in to qrx100s and while there was no visible reception improvement there was no digital artifacts or drop outs. Tested in wavelab. Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted November 2, 2015 Report Share Posted November 2, 2015 I am reading of new products coming on the market that are a concern to me. Amplified antennas should only be used for two reasons. It is to overcome the RF loss of long cable runs to a receiver (50 feet or more) or the RF loss of passive splitters used to drive multiple receivers. Any receiver used for the professional wireless industry has the optimum amount of RF gain as set by the manufacture. When used incorrectly adding gain to the receiver with a powered antenna will only serve to make the receiver overload more easily and will not enhance range any more than a passive directional antenna. Receiving an RF signal is all about signal to noise. Antennas with amplification can only amplify signal and noise at the same time not providing any real advantage. There is a feel good factor in that the signal on a meter may be higher with an amplified antenna but so is the noise so the benefit is hard to see if it is there at all. The other thing to watch out for is filtered antennas. You must know what the bandpass looks like to know if the filter is doing any good. Zaxcom receiver filters for example have a band pass of +/- 17.5MHz and attenuate about 30 dB at +/- 50MHz from the center frequency. If an antenna filter in front of the receiver has a +/- 50MHz bandpass and attenuates 20dB at +/- 100MHz away from the center frequency that is good to know as that will not provide good protection from interference. The point is, antenna RF filters are never the same and all manufactures should publish a frequency response graph so the the customer can understand exactly what the product does or does not do. With this information a proper system will be easy to put together. Glenn Sanders President Zaxcom Inc. With this in mind, here is a question: Zaxcom recommends the log period "Blue Fin" antenna. This antenna has a published spec of 8dB gain on axis. However, the same receivers are also used in bags and on cameras with a quarter wave whip antenna with a theoretical maximum gain of 3dB of gain. Does the input of Zaxcom receivers have 5dB of attenuation to reduce front end overload? If so, doesn't this reduce performance by 5dB when a whip antenna is used in a bag or on a camera? Should receivers have an attenuation switch to optimize the receiver for the antenna being used? Quote Link to comment Share on other sites More sharing options...
r.paterson Posted November 2, 2015 Report Share Posted November 2, 2015 're a micplexer 2 the 6db gain on outputs...does anyone know if this can be set to unity gain on outputs ie 0db.? I don't want any gain from the rf dist, only unity any gain what level comes in same level goes out on each output, I'd want any gain to come from anntena ie yagi or sharkfin..Thanks..Richard Quote Link to comment Share on other sites More sharing options...
RadoStefanov Posted November 2, 2015 Report Share Posted November 2, 2015 Richard, the gain in the micplexer is a good thing. in my experience the gain increases the range significantly. The XR modulation deals with noise very well so a little gain in the antenna distro does not seam to be a bad thing. Quote Link to comment Share on other sites More sharing options...
Derek H Posted November 3, 2015 Report Share Posted November 3, 2015 Zaxcom should consider designing a robust, flexible, harness-strap friendly dipole antenna. Maybe something similar to their filtered dipole antenna for the old stereoline transmitters but with a wider pass-band. And BNC connectors! Quote Link to comment Share on other sites More sharing options...
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