[Collins] KWM-2 S-Meter Sensitivity

[Byron Tatum]

OK-
    Thanks for reply Dave. Yes, I did notice that R-158 is chosen in 
production for correct S-Meter response. I researched R-158 some in regards to 
the Collins Service Bulletins and comments on the email reflectors.
    My KWM-2 is a RE unit that as best as I can tell was made somewhere around 
1967-68, based on D/C's of crystals and electrolytic caps. The 2 mentioned 
resistors in Service Bulletin at turret E-40 were already the new recommended 
values of 68K and with R-158 at 220 ohms
    I found the procedure of finding the correct value for R-158, whereby a 
resistance decade box is placed across R-158 to get the S-Meter to read S-9 
approx with 100 uV signal, with the receiver gain adj pot set for AVC threshold.
    I found that decreasing the value of R-158 (from 220 ohms) worsens my 
problem. Right now I have a 470 ohm resistor in for R-158 and my situation is 
better, but I still cannot peg the S-meter (with RF Gain backed off all the way) 
at the desired lower setting of receiver gain adj pot. With R-158 at 470 ohms I 
can peg the S-meter  (with RF Gain backed off all the way) at a lower setting of 
the receiver gain adj pot, however I still need to be able to reduce the 
receiver gain adj pot some more. I guess I will continue to increase the value 
of R-158.
    My concern is that I am adjusting the correct part for my problem, from all 
indications it appears R-158 is what I need to manipulate but I just wanted to 
ask others to be certain.
                                        Thanks, Byron WA5THJ