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Re: SBL-1 Mixer Question



Actually if you have alot of gain to play with, simply put 3-6 dB resistive 
50 Ohm pads on each port, and it works wonderfully.  (Conversion loss should 
NOT be a problem here) I'll probably get dinged by someone for suggesting 
this, but it works.  And in the case of the Drakes, Transystems, etc. out 
there driving it the loss might actually be beneficial.

You will find that it is VERY important to terminate all of the ports of a 
doubly balanced mixer.  The mixer will fail to work well otherwise.

The Minicircuits mixers are all specified for 50 Ohms impedance at all 
ports.  If I remember correctly it'll say "max VSWR" over Lo, Med, and Hi 
ranges in the data sheet.  If the VSWR in the data say 2:1 Max, that means 
that the resistive+reactive component will be from 25 to 100 ohms.  In most 
cases they are better, and even 2:1 is good enough.

But for "quick and dirty" use the 50 ohm resistive pads and you'll be set.

Fred W0FMS



>From: Matt Donohoe <m_donohoe@dingoblue.net.au>
>To: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] SBL-1 Mixer Question
>Date: Wed, 10 Oct 2001 21:59:13 +1000
>
>Hello,
>
>I am wondering if anybody knows what the input/output impedence of the 
>SBL-1 is for 122-124MHz Input with a LO of 96MHz and an output of 
>28MHz..... Is it 50ohms
>or different? Minicircuits doesnt give ANY specs!
>
>Sorry guys if you dont want to read this, but it's a bit hard to get 
>answers off Minicircuits!
>
>Matt Donohoe
>m_donohoe@dingoblue.net.au
>
>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


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