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Old 05-21-2018, 1:55 PM
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Default Info On 040165-002 UHF Duplexer

Hi there
Have anyone any info on the decibel product 040165-002 duplexer ?
Im intrested in adjuatment proicedure i cant adjust it i suspect the capacitors are not ok
Someone know what should be the capacitance of these capacitors and where can i buy such ?
Any info is Welcome
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Old 05-21-2018, 3:22 PM
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I'm not an EE, but it has always been my understanding that most (all?) Pass/Reject duplexers are passive, mechanical devices with no electronic components. They are usually tuned by adjusting each cavity, in combination with the recommended length of each connecting cable - which must be precise. You can often find on-line instructions for the tuning procedure, or contact the manufacturer for assistance.

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Old 05-21-2018, 7:18 PM
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You may be able to find the instruction manual on Repeater Builder, but I doubt the capacitor values would be listed in any parts list.

How are you adjusting it, and what is it that makes you think the capacitors are bad? In any case, they're going to be difficult to replace. I'd want to be darned sure they need it.
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Old 05-21-2018, 8:16 PM
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Quote:
Originally Posted by chief21 View Post
I'm not an EE, but it has always been my understanding that most (all?) Pass/Reject duplexers are passive, mechanical devices with no electronic components. They are usually tuned by adjusting each cavity, in combination with the recommended length of each connecting cable - which must be precise. You can often find on-line instructions for the tuning procedure, or contact the manufacturer for assistance.

- John AC4JK


Pass, or notch only cans do not have capacitors. Band pass/band reject duplexers have capacitors on the loops.


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Old 05-22-2018, 1:58 AM
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the symptoms are
1) I get no pass band at all it passess alll frequency like there is no Cavity at all no matter how i turn the tunning rod
2) I get no Notch ider
I have read article by duplexer repair company that mentioned that the Johnson capacitor failure is a common problem in DB product duplexers I suspect that is the problem in this case
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Old 05-22-2018, 7:30 AM
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The capacitor failure is a common problem, usually due to cracking from being dropped/rough handled or an overzealous tech with the wrong size diddle stick. Try Bird electronics, they still use the Johnson cap on their Pass/Reject duplexers.
Tuning instructions should be available as stated at repeater builder. You might also want to try and determine the newer part number for that duplexer as DB Products is long defunct, and information might be easier to find.

I have gone through the DB catalog and I can't find that part number, maybe a picture would help, or do your own comparison and find the newer model number.
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Old 05-23-2018, 1:54 PM
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Well... You learn something new every day! Here is an article from an Alabama outfit that specializes in duplexer repair. Scroll down to the section about capacitors:

Repair Services – Duplexer Repair

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