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Re: ft-736 problems with downconverters... help :)



There's two things you need to be concerned with regarding a "protector":

1.  Insertion loss
2.  Power handling ability

SSB makes a "protector" which has low insertion loss (.5 dB) at typical
downconverter IF frequencies (2M or 70cm). It isn't a dummy load but  takes
advantage of the fact that most modern, solid state transmitters sense SWR
and quickly reduce power (almost to 0) if they sense a significant loading
problem.  SSB's "protector" presents an infinite SWR to the transmitter,
causing it to effectively shut down.  In reality, there's maybe a couple of
hundred milliwatts that get through, depending upon the set, but most D/Cs
and preamps can handle that.

73 de Rick - KG6IAL

----- Original Message -----
From: "Scott Elliott" <scott@pieh0.co.uk>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, March 18, 2002 6:54 PM
Subject: [amsat-bb] ft-736 problems with downconverters... help :)


> hi there,
>
> ive read about the 736 accidently tx'ing into a downconverter when
switching
> from rx vfo to tx vfo. and as im getting a downconverter with not much
money
> to spend on replacing bits for it every month or so. i would like to know
> how a rf protector works.
>
> i assume its basically a dummy load up to what ever amount of power you
> build it too. but before building this and thinking it will work, then
just
> to blow it up anyways. i just wanted to check to see if my idea is
correct.
> i know it will stop the power, but im not sure what it will do to the
> received signal.
>
> plus if it is basically a inline dummy load type of thing. that would also
> stop any voltage going through to power the d/c. (just thought of that
> problem :).
>
> anyone got any ideas on this?
>
> thanks for any help :P
>
> Scott Elliott
> Scott@Pieh0.co.uk
> M1SJE / 2E1FJB
>
> ----
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> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>

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