[HCDX] Re: NRD-535 AGC modification

[Fabrizio Magrone <fmagrone@xxxxxxxxxxxx>]

Hello!

> anyone on this list familiar with NRD-535 modification for the AGC 
> circuit,  read there is a Kiwa mod for this but does it work only on 
> AM,  not also on SSB?

I modified my 535's AGC several years ago and, IMHO, it's a very useful 
improvement for this receiver and it works in all modes.
Modification is very simple. You must work on the "CAE-227A IF AMP UNIT" 
circuit board, connecting a resistor between the positive side of capacitor 
C104 and the negative side of capacitor C105.  Looking to the components 
side, C105 is near the upper side of the board, on the left; C104 is again 
on the left, in the middle of the board, just under IC7.  I chose a 840 
kiloohm resistor, but you can try other values to get different AGC times; 
a little 1/4 - 1/8 watt resistor will do.
This modification isn't mine, but I can't remember whose idea it was; 
anyway, a big thank you to its author!

73

Fabrizio


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