>------- Original Message -------
>From : Eric Lemmon[mailto:[EMAIL PROTECTED]
>Sent : 5/21/2005 4:05:15 PM
>To : [email protected]
>Cc :
>Subject : RE : Re: [Repeater-Builder] Poor Repeater RX
>
>Alexander,
>
>The
>Sinclair Q-202G duplexer can barely make 85 dB when tuned on a network
>analyzer, so that's the major part of your desense problem. It's only a
>four-cavity duplexer, specified at 80 dB minimum isolation, so no amount
>of tuning is going to make it operate at an isolation above its design
>limit.
While I don't disagree with what has been written, please realize that *most* commercial manufacturers 'rate' their highband/2M duplexer at 500 kiloHertz split, not 600 kiloHertz where most amateur 2 meter repeaters are operated. This added frequency separation allows for the duplexer to provide more than the stated isolation at the 500 kiloHertz specification.
The Wacom WP-641 is specified at 85 dB of isolation at a 500 kiloHertz split, but provides 93 dB of isolation at 600 kiloHertz. The Sinclair Q202G is similar in its factory specifications, and isolation provided.
Kevin Custer
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