2 Meter Portable Repeater

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zz0468

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And another thing, the 6 cavitie small mobile VHF duplexers are rated around 70dB isolation at 5MHz. How are you gonna keep that spec and narrow the BW by over 10X?
prcguy

That would fall under my previous post where I stated that I wasn't advocating the use of a 5 MHz spaced mobile duplexer. Remember that? It was only yesterday. I'm just saying that for a low power portable repeater, one doesn't need a $2000 high performance duplexer. One can get by with less.

I hear what you're saying, I understand, and I agree. But isolation requirements aren't always that stiff, if some intelligent compromises are made.
 

rescuecomm

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The Micor transmitter is running about 25 watts carrier out with about half coming out the helical filter set. It is probably doing the same thing to the receiver side with 3 db loss. However, being able to forward deploy the unit more than makes up the 2.0 db a larger duplexer would give us. I did try this duplexer on a Vertex VXR7000 repeater running 25 watts on a 3 mhz separation and the desense was too great to be usable. I ended up getting a larger flatpack rated to 2 mhz for that application. So the Micor front end really helps. So back to the question: Do I change the receiver or the transmitter freqs?

Bob
 

N7NEW

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Have built a portable 2 meter repeater with normal split and it works fine.
Go to
2 Meter Portable Event Repeater
Mounted everything in a small job box and have had no trouble with it after I changed the slug on the PLL board from to ferrite.
Later, Mike "N7NEW"
 
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