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[Yaesu] FT1000 switching diodes

To: <yaesu@contesting.com>
Subject: [Yaesu] FT1000 switching diodes
From: stuart@itron-ca.com (Stuart Rumley)
Date: Mon, 20 Jan 1997 09:15:15 -0800

Try this experiment.  Disconnect the antenna, switch in the attenuator (20dB).
Now turn the RF gain to max (normal RF gain position (S-meter should be
below S-1)).  
Turn the AF gain up until you hear noise.  Now switch between 250Hz (500Hz)
filter and
the 2.4kHz filter.  You should hear appreciable noise reduction (10dB in the
case of 250Hz/2400Hz).
If you do not, the noise is IF noise comming from the 455kHz amplifier
following the filter.


At 08:08 AM 1/16/97 -0600, Rob Emerson wrote:
>I have an older FT1000 that I think is experiencing IMD
>from the switching diodes that select the bandpass filters
>for receive. The noise does not go away switching in the
>attenuator. The best I can describe the noise is that it is
>the same as what happens when you switch in a noise blanker
>with a strong signal up or down the band.
>I have heard that Yaesu has a new type of diode (pin diode)
>to replace the switching diodes. Anyone gone through this?
>Rob Emerson, K0ZZ
>Computerized Medical Systems, Inc.
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Stuart Rumley KI6QP                             e-mail:         
Hardware R&D Manager                            Phone:  408/973-7024 
Itron Silicon Valley                                    Fax:    408/973-8647    
Saratoga CA

Home e-mail: stuart@ricochet.net

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