1. BITX20@groups.io

Re: Installing BCI and Kit-Projects AGC

Jerry Gaffke
 

The AGC board operates on two different signals in the radio.

AGC attenuation level is determined by measuring the audio signal level
after all of the filters that pick out only your signal of interest.
The AGC board is physically placed in the incoming RF path (not in the audio section)
so it can best attenuate the very low level signal coming in from the antenna.  

You might be right that the BCI filter would be better placed in front of the AGC board,
this could help if incoming AM broadcast band signals are 10 times stronger than all the shortwave signals.
But if the AGC board's RF attenuator is sufficiently linear, it won't make any difference.
I don't see any advantage in having the BCI filter after the AGC attenuator.

Jerry, KE7ER


On Sun, Jun 9, 2019 at 09:52 PM, Joel Trenalone wrote:
Hello All,
I have been working on a UBITX V5 and am installing both a BCI filter and the Kit-Projects AGC. According to what I have read regarding the BCI FILTER and the Kit-Projects AGC, both are installed by cutting in the RF receive path between K3 & K1. 

The way I read the schematic, the receive path travels from the antenna through K3 to K1 and on to the receiver. All the instructions (Kit-Projects and UBITX.net) show the AGC installed immediately after K3, then install the BCI then onto K1 (in that order). 

My my question is for the AGC to work properly, shouldn’t it be installed after the BCI filter (So the AM broadcast is filtered out)?

Please excuse my ignorance, but before I cut the trace and install these two modifications, I want to make sure they are in the right order,

Thanks in advance,
Joel KD6AGW :)
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