About this Modification:
The Argonaut 516 transceiver’s microphone gain control setting is critical for transmit signal quality.
The procedure for adjusting the microphone gain, as outlined in the manual, may result in excessive
microphone gain though there is proper ALC indication. This can result in a distorted transmit audio
signal and low tranmsit audio quality. To prevent this, a modification can be made to the ALC circuit
to raise the level at which ALC activation occurs. This makes adjustment of microphone gain less
critical and ALC overload less likely.
Does my Argonaut 516 need this modification?
This modification is not required. If you have not observed distorted transmit audio this
modification may not be necessary. If you have experienced SSB transmit audio distortion this
modificaiton should be made.
Not all Argonaut 516 transceivers need this modification. In October 2004, this change was
incorporated into the Argonaut manufacturing process. In addition, radios received for repair at the
factory after October 2004 will have been modified by the Ten-Tec repair department. You can
check the manufacturing date of the transceiver by looking at the serial number. The first two digits
of the serial number are the month of manufacturer and the last digit is the year. For example, serial
number
9
C1001
4
was manufactured in September 2004.
Parts Included with Modification Kit:
1
#30672
Resistor, 6.8k ohms, surface mount (marked 682)
1
#30674
Resistor, 10k ohms, surface mount (marked 103)
1
#30682
Resistor, 47k ohms, surface mount (marked 473)
1
#23196
Capacitor, electrolytic, 2.2mfd. radial leads
1
Short piece of solder-wick braid
1
Short piece of .031 diameter solder.
Tools Required:
1
#1 Medium tip Phillips screwdriver
1
Small pair of tweezers for holding chip resistors.
1
Small pair of wire cutters for trimming capacitor leads
1
Grounded tip 60Watt soldering iron with pencil or needle tip
1
Magnifier work lamp to make the job easier
Disassembly of Model 516 Argonaut:
!
1) Disconnect all cables from Argonaut.
!
2) Remove five(5) black Phillips head screws securing Top and Bottom Covers.
Field Modification of Ten-Tec model 516 Argonaut to
Reduce Potential of SSB TX Distortion.
