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Author Topic: FleaBay Duplexers  (Read 15487 times)
NF9K
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« on: December 18, 2012, 06:08:06 PM »

I'm working on converting a Kenwood TKR-820 over to 70cm.  The internal duplexers are the newer model that don't tune well into the lower 70cm band.  I'm trying not to dump a whole lot of cash into a new set of cans.  Checking FleaBay, I see a few Hong Kong sellers and a couple of China sellers that have duplexers similar to what I have now, but able to be tuned to where I need them.  A few offer free tuning as well. 

I've purchased a couple of things from HK sellers and had good luck.  Given that these were compact flash adapters and a Motorola mic.

Anyone have any experience with duplexers from HK sellers? 
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K1CJS
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« Reply #1 on: December 22, 2012, 06:01:40 AM »

I can only offer one thing concerning tuning.  Any amount of jarring from being tossed around--such as international shipping--will most likely make any tuning done next to worthless.  The duplexer cavities will probably have to be retuned when you get them to your location.  Don't plan on getting a pre-tuned duplexer set and using it right out of the package--it won't happen.
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N1OFJ
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« Reply #2 on: December 22, 2012, 07:18:36 AM »

I would not waste my time with these...you need pass/reject cavities and the ones I seen on that auction site look like reject only...this will not work if the repeater is going to a multi-user site.  Not only do you need great isolation TX/RX, but also some protection from the other emitters to prevent intermodulation products etc from happening.  Some tower sites will also require a circulator on the TX.
Hate to say it, but there is no cheap way to do it right.  I have been dealing with repeaters of all bands (6m-900 MHz) for 20 years and the only way to do it is correctly right from the start, otherwise you will be chasing your tail and spending good money after bad to fix the issues.....there are no cheap/band-aid approaches that work.
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N1RIK
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« Reply #3 on: February 15, 2013, 07:52:05 AM »

You can occasionally find a good set of Motorola T-1504 Pass/Reject duplexers for the $100 - 150 range on ebay.  They work quite well.  Mine are giving me better than 90 db of isolation on my 440 repeater, and allows me to run a 18 db preamp on it, while running 30-watts with not a whisper of overload.

But that's just my 2 cents Smiley

73s ~ Bill, n1rik
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K4JJL
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« Reply #4 on: February 15, 2013, 09:15:19 AM »

I have some Decibel cans that came out of a Mastr II Deskmate cabinet.  I'll hook you up, $100 shipped.  Let me know if you want some pics.  I can tune before I send them, but they usually get knocked out of tune in transit.
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