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[aprssig] Motorola radios for Satgates.

Spider spider at rivcom.net
Sun Aug 1 17:25:50 UTC 2004


----- Original Message ----- 
From: <scott at opentrac.org>
To: "'TAPR APRS Mailing List'" <aprssig at lists.tapr.org>
Sent: Sunday, August 01, 2004 9:58 AM
Subject: RE: [aprssig] Motorola radios for Satgates.


> >Incorrect de-emphasis? If possible, connect at the discriminator or
before
> >the de-emph network and build your own to "tune" to the application..???
>
> Speaking of which, has anyone got a good example of a passive high-pass
> filter to accomplish pre-emphasis on the transmit side?

Scott, a passive filter is very dependant on the load impedance on both ends
of the circuit.  Not sure 600 ohms is a good design impedance for some of
these ham radios anymore but just changing the input capacitor size is
sometimes more than enough using the input as the 'R' component.
Substitution boxes work wonders for quick determinations
with such a small frequency span!

Jim, WA6OFT












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