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thenannymoh

SNA600a dipoles performance over multiple blocks

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Looking for any experience people have with using their SNA600a dipole antenna to feed wideband receivers or receivers of different (but adjacent) blocks.  For example, if I were to have both block 21 and 22 in the bag, what (if any) antenna performance degradation could I expect by adjusting the dipole arm lengths to be roughly center for the combined blocks.

 

cheers!

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If you split the RX antenna length between the 21 and 22 marks and tune the 21 TXs to the higher end of their tuning range and tune the 22 TXs to the lower end of their tuning range your performance will be optimal. In theory, I believe this setup would be no different than using the full tuning range of a specific block. 

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My block setup is 24 / 25 / 26, each containing 2 channels, fed by 2 SNA600a's

Depending on how many channels I'm running I center the SNA freq.

Generally I run 4 channels, so I keep the freq at the very top of block 24, have never had any problems at all.

Even when I center it at 25, I don't get problems (that said I try to keep frequencies at the upper end of 24, or lower end of 26), range seems to barely be impacted if it at all.

 

You'll have no problems with 2 blocks.

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The bandwidth for a 2:1 SWR (Standing Wave Ratio) is generally considered a good operating bandwidth for an antenna. The 2:1 SWR of the SNA600 is +- 50 MHz or 100 MHz bandwidth or 4 full Lectro blocks. The 3 db down points are +- 75 MHz or 150 MHz bandwidth or 6 blocks. The frequency markings for the arms of the dipole are for centering the frequency range but don't exclude frequencies that are within a block or two of the center. The design was deliberately made wideband with the fat dipole arms. You can see that the real world operating frequencies described by the posters above (thanks) fall within these criteria.

Best Regards,

Larry Fisher

 

Edited by LarryF
100 MHz is 4 blocks not 2 blocks

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Others have answered but here is one more personal experience to add to the pot.  I once ran a musical theater show where I used a single pair of SNA600 antennas to feed 38 UHF receivers spanning blocks 470-26.  In that case I believe the SNA600s were fully extended so the block 24-26 stuff was outside the frequency range Larry mentioned.  It still performed flawlessly.

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All my wireless are block 19-22, I set the dipoles at near max length and dont need to adjust.  They are quite fantastic in that way, as Larry said above, since they cover ~100Mhz.

 

"Exact" quarter wave or half wave antennas would never work out given how often we need to adjust frequencies, it's always an average across a bandwidth.  The SNA600 more than cover the averages of multiple blocks.  I have 4 of them and use them for various wireless applications with great success.  I do want to test out the new Betso bow ties to test them against the SNAs, but from other reviews it seems they are more or less comparable.

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