[Moon-net] 13 cm system question.

[Steve Powlishen]

Trevor,

Something doesn't sound right with your Y relays. The
Transco spec is 36 dB minimum isolation, 40 dB typical @ 2 GHz.

I just measured a couple Y relays at 1.5 GHz.  Both had >43 dB isolation.

A "D" type relay will have better isolation, spec. is 60 dB @ 2 GHz.

Steve,  K1FO


At 03:58 AM 12/26/2007, you wrote:
>Hello all & I hope everyone is having a good xmas.  I anticipated
>becoming operational on 13cm about now but have struck an
>unexpected snag in the form of two blown preamp devices in a
>short period of time which usually is due to either incorrect
>sequencing or insufficient isolation.
>The sequencing is ok & the same as I have used for other systems
>with never a damaged preamp.
>I measured the isolation between ports of my Super VE4MA feed
>with septum & found it to be 22 db.  Next I measured at 2301 MHz
>the isolation of the Transco Y relay [type 11300] & discovered it
>was only 18db.  My spare 11300 Transco is even worse at 15.5 db.
>With 40 db of isolation & 120w at the feed this means the ATF36077
>is seeing 12 mW at its gate with the spec sheet indicating the "absolute
>maximum" not to exceed 10dbm.
>I have been unable to get isolation fiqures for the Transco Y relay
>at 13cm though the info is out there somewhere however I would
>have thought it would be considerably better than 18db?
>In any event another SPDT relay with female N connectors is required
>before any progress is made & I welcome suggestions.
>Tnx for your time.
>
>   73`s, Trevor,  VK4AFL.
>
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