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Subject:  Kantronics KAM HF frontend modifications
From: Warren Stone 60dB (KAM)        >80dB (KAM+)



With the help of the schematic and the component layout diagram for the

KAM the location of components is simple and the use of a solder sucker

to clear the holes for the double sided PCB will facilitate a clean job.



Components to replace;

     OLD   NEW

R17  470   100     (All 1/4 watt carbon resistors)

R18  47K   68K

R19  2.2K  10K

R27  15K   2.7K



Remove CR11 and reinstall with polarity reversed

Remove CR5 and discard

Lift the end of R13 that is common with R1.



Insert one end of a .1uF 50V capacitor into the PCB hole vacated by the

end of R13 common to R1; solder in place.

Connect the other end of this cap to the free end of R13.

Install a 100K 1/4W resistor between the free end of R13, the .1UF CAP

and ground.  Use the PCB hole vacated by removing CR5 (ground side).

You end up with a tripod of components.



CAUTION: Some PCB holes having double sided traces may need to be

soldered on both sides of the board to ensure a through board solder job.



This completes the update modification for the KAM.

You will notice a better dynamic range for input signals to the KAM

and an improved limiter using the FM/AM front panel switch.  I noticed an

improvement in throughput when operating AMTOR/PACTOR.  I also noted improved

CW reception using the 'AM' position of the FM/AM switch providing perfect

copy on 160M CW signals.



I would appreciate any feedback on this modification or other improvements:

K5HK


73,  CARL YOUNG, K5HK /MM2

     ABOARD SS KAINALU



HOME QTH: 983 LESTER AVE.

           RENO, NV 89502





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KAM VHF front end improvement                         7 April 1995



Original KAM VHF port audio sensitivity 20mVpp, >60dB dynamic range

KPC9612, KPC3 VHF port audio sensitivity 5mV, 70dB dynamic range



The KAM uses the same modem IC as used in both the KPC3 and KPC9612.

By changing some components the KAM VHF performance can be improved to

the same specs as the KPC3 or KPC9612.



To improve the KAM VHF performance;



Remove R4, R8, Q4

Remove and place jumpers in place of C14 and R6

Replace R9 6.8k with 100k

Replace R26 6.8k with 100k

Replace R28 15k with 470k

Replace C6 0.001uF with 0.01uF



K1 position 2 or off, equalization off

K1 position 1, equalization on



This will change the configuration of the original KAM VHF front end

to be similar to the KPC3 and KPC9612.  I use a Mocom70 with direct

audio feed from the discriminator.  There is no way to simply increase

the volume level to get more audio.  There is a great improvement in

the VHF port performance of my KAM since making these changes.



73 de Warren VO1KS



Packet VO1KS
Email  ar772