Cubic R3030 AGC

[WA1GFZ]

I've spent the past few weeks reverse engineering a few different Cubic Detector modules. R3030, R2411 and R3050. I found some interesting circuits.
The R2411 and R3050 have an AM detector similar to the K2CU AM detector.
actually Rob had a version just like the Cubic before he came up with the present design. Anyway all of these modules have the same average AGC for AM. It is way too fast with a fast release time. It will be easy to change it to a dual time constant fast attack/slow decay with the addition of a diode and resistor. The AGC charge cap value varies in different models. I'm looking for opinions on attack and release times because it ends up just value selections.
Anybody out there have Cubic receivers with comments?
Cubic dropped the hang type AGC in the 2411 and 3050
The 3050 Detector has a ceramic tail filter to reduce noise.
Cubic changed some of the digital AGC control from the CPU that will make it interesting to get the newer modules work in the 3030. 

[WA1GFZ]

Here is the simple modification to eliminate the AGC hang circuit. When I was done and I listened a bit maybe the issue is C66 is too large causing a big delay in the AGC and R92 a 22K the discharge resistor is too small but I didn't go back and check. This change gives you about the same discharge time constant .05, .25, 3.0 sec.
1. Remove Q14 AGC discharge FET (controlled by U6B -12 one shot )
 
2. Remove R91 a 1Meg resistor between U6B-7 and VCC.
 
3. Install the 1 MEG resistor across the outside pads of Q14 (Drain -Source) This is the new AGC discharge resistor
 
4. Drill out plated through hole or cut trace at R91 U6B-7 side (to get oneshot out of circuit,)
 
5. Connect jumper U9 4066 pins 9-10 to pin 7. (grounds new timing caps)
 
6. Remove C66 33uf/25V near U9 (old AGC storage cap not necessary)

 
7. Connect jumper C66 positive side pad to the bottom side board from R91 connected to C28-.047uf, C67-.22uf and C68-3.3 uf positive side. (These are the new AGC timing caps.)
 
The .05 and .25 AGC positions are pretty active so you might want slower settings it is easy to modify by changing the cap values. There is a lot of static tonight and .05 really catches the static peaks. A bit fast for SSB. 3.0 seconds sounds fine.  Pretty easy to back out depending on how you break the connection to U6B-7.  Timing .05= C28 &1Meg,  .25= C28+C67 &1Meg,   3.0= C28+C68 & 1Meg
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AM Agerage Cubic increased C65 to 10uf in later receivers. The value in my module is 2.2uf. I like the higher value better.