[Moon-net] 13 cm system question.

[w2drz]

Trevor,

Check out some good SMA relays, as some of those for receive use maybe
just what you need for high isolation..

tom W2DRZ



Trevor Benton 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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