Larry wants to use separate receivers and transmitters -
possible different antennas for the receiver and transmitter.
In this situation for protecting the receiver, it must be
completely isolated from the antenna during the transmitting
time by a good antenna relay, PIN diode switch or high voltage
PhotoMOS switch. Also, for best protection the receiver
antenna terminal should be shorted using same kind of devices.
I have used NAIS or Panasonic PhotoMOS AQV204 that can stand
400 V and switches in less than 100 µs.
See:
http://www.datasheetarchive.com/semiconductors/pdfdatasheet.php?Datasheet=387760
Naturally, carefully designed sequencing and switch driver
circuits will be needed. Still, due to switching transients a
good "RF" mute may be necessary.
73, Ahti OH2RZ
----- Original Message -----
From: "Jim Lux" <[EMAIL PROTECTED]>
To: "Larry W8ER" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
"'Flex Reflector'" <FlexRadio@flex-radio.biz>
Sent: Wednesday, December 14, 2005 11:16 PM
Subject: Re: [Flexradio] Mute for SDR Receiver
At 08:28 AM 12/14/2005, Larry W8ER wrote:
Eric .. I would like to eliminate all other receivers from
my ham shack.
The Flex is the best. Occasionally I like to fire up an old
boatanchor AM
transmitter or something other than the Flex transmitter. I
am looking for
a way to mute the Flex receiver. Killing the audio is fairly
simple but in
doing so the Flex hears the big local signal and upon return
to receive,
the AGC has to recover and so forth. A good clean mute is
what I am after.
I think the confusion might be with what "mute" means,
because I think most
folks thought it meant shutting off the AF output, but what
you mean is an
"RF" mute, or at least one that freezes the AGC.
Jim
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