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The Kenwood TS-711
Multimode 2 meter transciever

Factory Specifications Modifications            Computer Interfacing Links             
Overview

       The Kenwood TS-711a is, more or less, the 2 meter twin of my TS-440. The features are similar, and the styling is identical. Both units were introduced at about the same time, and even use some of the same accessories (such as the computer interface). This makes it a classic knob and dial turner, and button pusher. Unlike the HF model, the 2 meter version has a built in power supply, and can be plugged directly into the wall. This is an all mode transceiver, and is not limited to FM like most 2 meter units. There was also a third member of the family: the TS-811, a 70 CM unit. This was Kenwood's middle range series.
       The unit puts out 25 watts. This is enough power for local communications, within the limitations of the 2 meter band. It is also enough power to run a good quality linear amplifier up to full rated power. I plan, in the near future, on getting a linear amp for this unit. Mirage makes a suitable unit, which puts out 160 watts, and is capable of multi-mode (including FM) operation. This should give me a respectable amount of power, for local operation, and still be within the capability of the 42 amp power supply which runs my shack. The Mirage has a clamed current draw of about 20 amps, which still leaves plenty in case I wish to operate the linear and my TS-440 HF at the same time. It is unlikely that I will ever wish to do this, but it is comforting to know that the capability is there if I need it. Output is continuously adjustable, via the RF PWR knob, from 2 watts, up to the maximum of 25.
        Hitting any of the mode buttons to change mode generates a Morse code beep announcing the new mode selected. The main reason I selected this unit for my shack is that it is capable of all mode operation. the majority of 2 meter units out there are FM only. I don't know how much SSB or CW I will be using on two meter, but it's good to have the option. Frequency can be set in increments as small as 5 KHz.

        This unit has the optional speech chip, which was thought to be a very big deal back in the 80's, when digital technology was novel and just coming of age. Today, it seems kind of silly and quant. The speech chip announces, in a pleasant female voice, any frequency changes or mode changes that I make - 80's high tech. the unit also has the tone board, which was an option back in the eighties, but is certainly a requirement these days. This is also one of the earlier units to be capable of computer control. An optional chipset (IC-10) must be added, along with a level converter for RS-232C.

         There are 40 memory locations available in this unit. Each can store frequency, shift, and tone. The last three can store two separate frequencies to be worked as a split. This is a nice feature which somewhat compensates for the 600KHz non adjustable offset of the 711. With the tone card installed, the unit is capable of selecting between 37 tones from 67 to 250.3 Hz.

       The transceiver is capable of  shifting the receive frequency up to 9.99 KHz, using the RIT control. It is also capable of shifting the receiver passband, through use of the IF shift control. The unit also has scanning features, due to an early version of computer control, and an eighties era microprocessor. Scanning can be done fo segments of the band, or of the memory locations. You can also set a particular memory location for an alert, anytime it shows activity. A DCS feature allows the radio to respond to tone alerts or calls.

       Though this is of the same series as the TS-440, and shares that unit's all mode operation, the TS-711a is a bit less capable. In particular, it is missing many of the connections, which give the HF unit so much of it's flexibility. The rear panel features an antenna connector, ground, power connectors for 120v and 13.8 volt, computer interface, and audio jacks. Most activity, on the two meter band, is FM, making it hard for many ham operators to justify the expense of an all mode radio. To properly use the radio to its full potential, it should be hooked up to a vertical antenna for FM, and a horizontal dipole for SSB.
 

Antenna System

        Wow! Is there ever an abundance of material on how to make a two meter antenna.  This is an extremely popular band, and antenna matters are very interesting to most radio amateurs. Due to space limitations, I was unable to do anything very elaborate. I had considered several ideas, but finally went the very conventional route. I made myself a horizontal dipole for AM and SSB, and a modified version of a J-pole, called a Slim Jim for FM. The dipole is essentially three feet of wire, and the Slim Jim is about twice the amount of twin lead - simple.

        One great thing about my two meter station is that it is single band - one band, one antenna. This means matching the antenna once, and then  leaving it be. There are no recurring worries about SWR, tuning, or cable loss. Yes, VHF losses are greater in coax than those at HF frequencies, but this is all related to SWR, and SWR can be kept very low in a single band system. I do prefer to swap between the horizontal and the vertical, when I change operating modes, but this is a minor inconvenience. Lately, when I wish to operate in FM mode, I use my Azden 6000, rather than my Kenwood.

 


Specs
The following specs were taken from Kenwood literature:
Modes LSB (A3J), USB (A3J), CW (A1), AM (A3), FM (F3), FSK (F1)
Antenna Impedance 50 Ohms
Grounding Negative
Power Requirements 120v / 13.8v
Current Drain Receive Mode with no input 1.2 amps
Transmit Mode 6.5 amps
Operating temperature -10 to +50 C (+14 to +122 F)
Dimensions Wide
High
Deep
10.6 Inches
3.78 Inches
10.2 Inches
Weight 15.6 Pounds
Transmitter
Frequency range 144mhz-146mhz
Input Power LSB, USB, CW, FM, FSK 25 watts
AM 25 watts
Modulation LSB, USB Balanced Modulation
FM Reactance Modulation 
AM Low Level Modulation
Spurious radiation (CW)  Less Than -60 db
Carrier Suppression  More Than 40 db (With 1.5 KHZ Reference)
Unwanted Sideband Suppression  More Than 40 db (With 1.5 KHZ Reference)
Third Order Distortion More than 26 db below one of two tones
Maximum Frequency Deviation (FM)  5 KHZ
Frequency Response (-6 db) 400 to 2600 HZ
Microphone Impedance  500  to 600 Ohms
Receiver
Circuitry Double Conversion Superheterodyne
Frequency range 144mhz-146mhz
Intermediate Frequency 1st: 30.265 MHZ, 2nd: 10.695 MHZ, FM: 455 KHZ
Sensitivity LSB, USB, CW, FSK
(At 10 db S/N)
less than .13uV
AM (At 10 db S/N) less than .13uV
FM (At 12 db SINAD) Less Than 0.2 uV
Selectivity LSB, USB, CW, FSK -6 db 2.2 KHZ
-60db 4.8 KHZ
AM -6 db 2.2 KHZ
-60 db 4.8 KHZ
FM -6 db 12 KHZ
-60 db 24 KHZ
Squelch Sensitivity LSB, USB, CW, FSK 100 to 150 KHZ Less Than 20 uV
FM  1.6 to 30 MHZ Less Than .32 uV
Output   2 Watts at 8 Ohms (5% Distortion)
Output Load Impedance 4 to 16 Ohms
Frequency Accuracy  Less than .00001 error
Frequency Stability  Less than .00001 error


Mods
As with most commercial ham radios, there are a number of modifications and enhancements that can be made, many by the owner.
Extended Transmit Frequencies:
  • Remove the top cover and locate the control unit (X53-1410-XX)
  • Cut diode D30, xmit now 141.000 TO 150.995 MHz.

Computer Interfacing
    The 711, as part of the same series as the TS-440, interfaces to a computer in the same manner. Rather than simply cut and paste the same information here, I will link to the pertinant section on the TS-440.

Links
Manual Eham Review