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Decibel Products DB4140-2A VHF Notch Duplexer

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#1
I have been trying to locate a specification sheet for a Decibel Products DB4140-2A VHF Notch Duplexer. I'm interested in the frequency range, Minimum frequency separation and insertion loss. Normally I can find spec sheets for most DB Products duplexers but this one seems to be some what of a mystery.

Any information will be appreciated.
 

buddrousa

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Jan 5, 2003
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NW Tenn
#2
What is the intended input frequency and the intended output frequency?
The set on ebay from AZ Highway Department range from 150-156's and are very old. We had a set that worked 300Kz they were a lot larger and very expensive.
 
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Dec 10, 2008
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46
Location
Phoenix, Arizona
#6
Thank you for the information sheet. I think this confirms my suspicion that the duplexer was constructed of individual filters and not as a set by the manufacturer. It should still work but I would be more confident if they were a matched set.

Thank you again for all your posts.
 

chief21

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Summer - western NC; Winter - Tampa Bay FL
#7
I think the important distinction here is that this item is listed as a "Notch Filter" rather than a "Duplexer". A typical VHF Pass/Reject duplexer is much larger and usually consists of multiple filters. This device is a single filter and is apparently intended to notch out a single interfering signal. I don't think that I would attempt to use this with a repeater in lieu of a true duplexer (if that is your intent) as I'm not sure that you would get the necessary isolation between the transmitter and the receiver.
 
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