[R-390] Break In
David C. Hallam
dhallam at rapidsys.com
Wed Dec 5 10:18:48 EST 2007
I have found that in addition to operating the break-in relay in my R-390 on
transmit I have to open the RF gain terminals on the rear terminal strip to
completely mute my receiver.
David
KC2JD/4
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of
> Flowertime01 at wmconnect.com
> Sent: Wednesday, December 05, 2007 10:06 AM
> To: R-390 at mailman.qth.net
> Subject: Re: [R-390] Break In
>
>
> Collin,
>
> Break-in opens the antenna input relay and opens a circuit in the
> audio path
> some where after the diode load.
>
> It depends on how much RF the transmitter radiates around the
> shack to the
> receiver and how much RF is radiated across the open relay
> contacts in the
> receiver.
>
> Also you now have the external amp subject to RF exposure.
>
> You should be able to operate the receiver break-in relay from the
> transmitter keying circuits.
>
> The receiver audio as heard in the speakers should then be
> reduced to just
> the noise of the receiver and amplifier. The RF from the
> transmitter should be
> at a low level that does not radiate into the receiver and
> amplifier to cause
> sonic howls. If the transmitter when keyed is causing more audio
> output than
> just the noise level you have if you short the break-in terminal
> on the receiver
> to ground then you need to get some shielding between the
> transmitter and the
> rest of the equipment.
>
> If you want the audio to mute when you go to break-in, then you
> will need a
> relay between the Diode Load output and the external amplifier.
> You will need
> to devise your own power source and keying circuit for that extra
> relay. Once
> you get that taken care of you then have to consider how badly
> the audio pops
> as the relay goes from passing audio, to open circuit, to
> grounded input as the
> relay switches. There will be another pop as the relay comes out
> of break-in.
> Many audio circuit things to think about as you make improvements to you
> stations operation.
>
> But then it is winter and time to work on these problems as you
> hug your warm
> glowing equipment.
>
> Roger AI4NI </HTML>
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