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Re: Yeasu FT480-R discriminator mod?



At 15:32 20/11/2001 +1100, you wrote:
>Before I try to reinvent the wheel, does anyone know of  a mod to the 
>FT480-R to allow for a centre-zero discriminator meter?
>  The discriminator itself is a 5 pin monolithic device of some sort, 
> SFD455S4. I suspect it may be a ceramic device.
>
>MAny thanks
>Norm, VK2XCI
>Voice of The Edge of The Outback
>njmcmillan@bigpond.com
>
>----
Thanks to those who replied thus far.

The device in question is in fact a ceramic discriminator, effectively a 
`black box'. I now have a circuit diagram of the Rx!!. The two outputs 
appear to be balance by a 5k6 resistor to earth from each pin, then a joine 
by two series diodes. From the junction of the 2 diodes are 2 audio feeds, 
one to the squelch amp via a lpf, the other to the audio chain via a 
squelch switch and de emp network

out1    0------->|-------------0-to audio etc.
         |                       |
         5k6                     |
         |                       0 I guess I'll try here!!!
         earth                   |
                                 |
                                 |
out 2   O-------|<--------------0-to squelch amp
         |
         5k6
         |
         earth
Murata list the device as "obsolete"!!!!!


73

Norm, VK2XCI
Voice of The Edge of The Outback
njmcmillan@bigpond.com

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