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Thread: best antenna

  1. #2181
    Flight attendant LDSP's Avatar
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    STR_EDDS....If I can see your antenna was so close to chrome pipe handle.Reception would be better if kept away from it ,reckon.Anyway, very crafty look like factory made! Well done!

  2. #2182
    Captain abcd567's Avatar
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    Quote Originally Posted by LDSP View Post
    STR_EDDS....If I can see your antenna was so close to chrome pipe handle.Reception would be better if kept away from it ,reckon.Anyway, very crafty look like factory made! Well done!
    You are right. To avoid reduced performance, antenna should be away from metal objects. As a bare minimum, it should not be less than one wavelength away (30 cm / 1 ft in adsb case).

    You are very observant. Thanks for pointing out. I checked again the photos STR_EDDS has posted. The lowest leg of Franklin is not only close, but looks as if is touching the chrome handle (in this case chrome handle is antenna's part now and affecting Gain & SWR). Also the lowest leg's entire length is behind the wall blocking adsb signal to lowest leg from the direction of wall. Anyway, even with these things, the STR_EDDS 's Franklin gave good performance.
    Last edited by abcd567; 2015-01-26 at 18:34.

  3. #2183
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    i put it there only for the pictures
    for the tests i raised the antenna in the air with my hands.

  4. #2184
    Captain abcd567's Avatar
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    Quote Originally Posted by STR_EDDS View Post
    i put it there only for the pictures
    for the tests i raised the antenna in the air with my hands.
    Wow, you stood at top of tower holding antenna in your hand for 15 minutes in this freezing temprature & wind!! I will quit in less than 5 minutes.

  5. #2185
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    Quote Originally Posted by abcd567 View Post
    @charan:

    Another Amplifier circuit from Infineon (Siemens), one of the manufacturers of transistor BFP420

    Source: http://www.infineon.com/dgdl/AN018.p...1427688a990761

    Attachment 5334 Attachment 5335
    Hello back again ! I got BF420 from local website. so i made this lna https://blackbirdengineering.files.w...013/05/lna.png and result is stunning.! haha better reception without lna..
    i made exactly as shown in circuit (trust me) except for powering up from coaxial i removed C2 and R2 and placed them near receiver and powered it with 5.22V.fm with pwer.jpg <- this is with power and see what happens when i disconnected power (but not lna) with out pwer.jpg


    Please help im getting headache with these !
    RTL SDR : T-VEVZ1

  6. #2186
    Captain abcd567's Avatar
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    A 6 element Franklin recently built by "Karin" - Nice built!

    Karin-P1260120a.jpg . Karin-P1260119a.jpg

  7. #2187
    Captain abcd567's Avatar
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    @ charan:

    (1) You are testing at FM frequency 93.5 Mhz instead of ADSB freq. 1090 MHZ

    (2) At high frequencies like ADSB, printed circuit board layout or connection wiring plays a significant role. Did you use the printed board layout shown on the web page https://blackbirdengineering.wordpre...lna-for-ads-b/ ?

  8. #2188
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    Quote Originally Posted by abcd567 View Post
    @ charan:

    (1) You are testing at FM frequency 93.5 Mhz instead of ADSB freq. 1090 MHZ

    (2) At high frequencies like ADSB, printed circuit board layout or connection wiring plays a significant role. Did you use the printed board layout shown on the web page https://blackbirdengineering.wordpre...lna-for-ads-b/ ?
    I got it working ! yay.... contact issue.. but yes i want it for Airband so testing with FM but now got another problem FM is interfering with airband.... every where FM only from around 70mhz to 160mhz :/ ! can you please give circuit for BFP420 for airband ? ill shift this for ADS-B and will let you know the results soon !!!! ( seems like this specified circuit is for ADS-B only).!
    RTL SDR : T-VEVZ1

  9. #2189
    Captain abcd567's Avatar
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    @charan:
    You need to add filter at input of amplifier to reject FM and other TV and communication VHF bands. A band-pass filter for air band will reject frequencies higher & lower than air band and pass only air band to amplifier.

  10. #2190
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    Quote Originally Posted by abcd567 View Post
    @charan:
    You need to add filter at input of amplifier to reject FM and other TV and communication VHF bands. A band-pass filter for air band will reject frequencies higher & lower than air band and pass only air band to amplifier.
    Oh thanks !
    RTL SDR : T-VEVZ1

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