[Top] [All Lists]

Re: [TowerTalk] Help need Vacuum Relay Isolation 1.8 to 30 MHz

To: "Jim Lux" <>,"RCARIELLO" <>,"Towertalk" <>
Subject: Re: [TowerTalk] Help need Vacuum Relay Isolation 1.8 to 30 MHz
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Wed, 5 Jan 2005 02:02:29 -0500
List-post: <>
> Even though the relay mfr only guarantees 40dB, you have
seen 60 dB?

Sure. I measure it all the time with accurate instruments.

> wouldn't be surprised, since the mfr is specing a "worst
case under all
> conditions and all manufacturing variation" kind of
number.  Array Solutions
> quotes 60-65 dB kinds of numbers for their AS1GRS232, and
55-60dB for the
> SixPak (typical, not guaranteed), but doesn't quote any
specs for the
 RatPak, etc.

The Rat Pack I measured had -51.7 dB crosstalk on 14 MHz,
and -45.3dB on 30 MHz.

> But even with 60dB, you're still putting 0dBm into the
second receiver. If
> you're expecting same band operation, that's a pretty
challenging dynamic
> range requirement if you're looking for narrow band
signals at  -150 dBm
> close to the noise floor.

I don't understand why anyone would worry about that.

Not only is that clearly NOT how he intended to use the
switch, the path loss between antennas and other things
external to the switch would be an even bigger problem.

Typical receivers will easily handle 30dBm without ill
effect when you are not duplexing on the same band.

73 Tom


See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>