Originally posted by abcd567
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My first collinear antenna
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Originally posted by FR24-BB8 View PostI´ve also ordered a flightaware bandpass filter that i will connect as soon as it arrives.
You may use a satellite amplifier (950 mhz - 2050 mhz)+power inserter+ac/dc adaptor 15v dc, with your DVB-T
O R
Use Flightaware ProStick which is DVB-T with built-in amplifierLast edited by abcd567; 2016-06-20, 21:23.
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Originally posted by abcd567 View PostThe FA band pass filter, and for that matter all filters have insertion loss of several dB. Your signal may require an amplifier to cover for this attenuation.
You may use a satellite amplifier (950 mhz - 2050 mhz)+power inserter+ac/dc adaptor 15v dc, with your DVB-T
O R
Use Flightaware ProStick which is DVB-T with built-in amplifier
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Flightaware filter Specs:
"They have SMA connectors (male and female), pass 980-1150MHz with an impedance of 50ohms and insertion less of <2.5dB."
See here:
FlightAware ADS-B filters now for sale worldwide
And here:
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Attenuation of two filter chips:
Insertion Loss
Chinese TAI-SAW 1075 to 1105 Mhz = 2.3 dB typical, 3.0 dB max
USA TriQuint 1085 to 1095 Mhz = 2.6 dB typical, 4 dB max
Specifications (pdf)
1) Chinese (TAI-SAW) Filter: http://www.taisaw.com/upload/product/TA1090EC.pdf
2) USA (TriQuint) Filter: http://triquint.com/products/d/DOC-B-00000374
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My first collinear antenna
I've now had my new coax only spider (with 20mm horizontal radials before bending) up for two days, and my impression is that the range is decreased, I'll post the range plot later today. The best antenna so far is my first coax only with radials bent 45° directly. So tonight I will reattach that one and wait for my FA bandpass filter. According to FR my top range is 175 nm with the first one. Around 130 with the others.
Cheers
/P
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whatch this video it explains decibels quite nicely then you will see how big the difference between several and your examples.
https://greatscottgadgets.com/sdr/3/T-EGLF8
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Originally posted by SpaxmoidJAm View Postwhatch this video it explains decibels quite nicely then you will see how big the difference between several and your examples.
https://greatscottgadgets.com/sdr/3/
Thanks for video link, but I dont need this video to undersatand meaning of dB. I am already fully conversant with dB and fully understand what a dB means, and how it is calculated (10 log P1/P2). For just quick understanding of hobbyist, amplification by each 3 dB means doubling the power, and attenuation by each 3 dB means halving the power.
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Originally posted by FR24-BB8 View Post@abc567
According to your figures earlier in this thread, how much gain do I get from these spiders? I mean if I get around 2 dB loss with the filter, am I all out of signal then?! [emoji16]
The dB is the log of ratio of signal to a reference signal level. Hence signal in dB = 10 log S/Sr, where Sr =reference level. For signal level equal to reference level, S/Sr =1, and sinal in dB = 10 log 1 = 0 dB.
So zero dB means signal level equal to reference level
Even with less than 0 dB (i.e. negetive values of dB), the signal is not zero
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Here´s my range plot with the second coax:
Sk&#228;rmklipp.PNG
Compared to the earlier:
coax-only (1).PNG
They both are attached for the same amount of time, approx two days.Last edited by FR24-BB8; 2016-06-22, 21:43.
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