Quote:
Originally Posted by Flint Ridge
The fog is kind of clearing now with the concept of the HLSJ to truly scrub out those signals.
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ADTech made some measurements of 2 HLSJs and I added some notes to the results to help me understand them. This might help clear the fog:
ADTech quoted:
Quote:
An HLSJ will pass EVERYTHING below the cutoff frequency (down to DC) through the "LOW" port unless it has a capacitive input on the LOW port. Neither of these two devices use that layout.
You just have to know the relative transition frequencies to select which might be appropriate.
I tested the Holland and Pico/Tru-Spec HLSJ devices a while back. The Holland starts to roll off between 100 and 110 MHZ with about 3-4 dB IL at 108 MHz. The Pico/Tru-Spec started rolling off between 110 and 120 MHz.
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http://www.digitalhome.ca/forum/81-o...ml#post1396123
comments by holl_ands:
Quote:
ADTECH measured the Frequency Response for both the Pico-Macom and Holland versions of the HLSJ (Hi-VHF/Lo-VHF Diplexer).
On the Lo-VHF Port, Insertion Loss for the tested Holland HLSJ unit was very low on Ch2-6, increasing across the FM Band to about 3-4 dB Insertion Loss on 108 MHz (Top of FM Band), whereas the measured Pico-Macom unit only had about 1 dB Insertion Loss.
On the Hi-VHF Port (actually Ch7 thru UHF), the Holland HLSJ had at least 25 dB Insertion Loss across the FM Band, increasing to as much as 40 dB in the upper part of the FM Band, whereas the measured Pico-Macom unit had at least 28 dB Insertion Loss, increasing to as much as 40 dB in the middle of the FM Band and reducing to about 30 dB on 108 MHz.
So YES, they are both effective as FULL BAND FM FILTERS.....but they also Eliminate Ch2-6 if that is an issue for you.
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http://www.avsforum.com/forum/25-hdt...l#post30726945
Holland specs:
http://www.hollandelectronics.com/ca...-Diplexers.pdf
There is a long thread here about FM filters:
http://www.avsforum.com/forum/25-hdt...fm-filter.html
post #23 of 124 has curves of the MCM FM Filter:
http://www.avsforum.com/forum/25-hdt...l#post29973297
http://www.mcmelectronics.com/produc...-FM-88-/33-341
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