[NLRS] DEMI 10368-144 Bias Circuits

[Dr. Gerald N. Johnson]

That is the DEMI PPS-1 board. I don't have a layout, but I have a 
picture and a complete schematic, in a paper for CSVHF next weekend. Its 
also on line at > http://www.geraldj.networkiowa.com/papers/2012/pps1c.pdf

and in the documents somewhere at DEMI, should be under PPS-1.

Its always powered I think. That depends on how that power supply is 
connected to the TC board that switches voltages around. The board 
primarily supplies negative bias required by the FET in the low noise 
option
> http://www.geraldj.networkiowa.com/papers/2012/OldDEMI10gcolor.pdf

and the transistor slows the drain voltage to give the 7660 time to 
create the bias voltage as the older FETs didn't like a drain supply 
without bias. Its also almost the same as in some preamps documented on 
DEMI. Another paper I'll be presenting Saturday and also on the DEMI web 
site somewhere.

These were published in the SEVHF proceedings last April also. The 
printed versions aren't in color like these.

73, Jerry, K0CQ

On 7/22/2012 9:45 PM, Melvynkc0p at aol.com wrote:
>
>
> I am looking for info on the ICL7660 Voltage Divider circuit board  that
> feeds the first Rcv gain stage with about +4.5 volts. This is for a
> transverter built about 2001. Most helpful would be layout of the
> separate little circuit board on the circuit side.
>
> Is the input to the switched capacitor chip always powered or just
> in receive mode ?
>
> I have looked on the DEMI website and cannot find it, nor can I find
> any of my hardcopy documentation (not surprizing !)
>
> Any help would be appreciated.
>
> Mel KC0P
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