^rHelp for Tune Channel^r

The [+] and [-] keys are used to  increment or decrement  the value of
the parameter being adjusted.

^rSQUELCH TUNING:^r
Use the  UP or DOWN  arrow key to select the Squelch item.  Switch the
radio off and on.  On the right side  of the  squelch value the actual
squelch status  is shown.  This field lets  the user  know  whether or
not carrier squelch has been detected  by  the radio's receiver.  This
allows you  to set threshold squelch on those channels which are PL or
Select 5  protected.  Once you have selected the squelch field  follow
the procedure given below.



* With no  RF signal applied to  the radio,  set the squelch  value to
zero  (0)  by using the [-] key.  You should  read  the  status "Radio
unsquelched".  If the channel is a carrier squelch channel  you should
hear the noise through the speaker in the test set. Make sure you have
the test set at the speaker position instead of the  load position and
the volume on the radio set up  high enough so  that you  can hear the
noise.

* Increment  the squelch value by  using the [+] key  until  the radio
squelches (no  noise  present),  the  status  field  will  show "Radio
squelched".  Then increment  the value by  one (1)  using the [+] key.
This setting is defined as threshold squelch.




* You can now set the  same squelch value  to all the  channels in the
radio by pressing the [F9] key.  Pressing the [F9] key  will cause the
current squelch value to be copied over  to all the  other channels in
the radio.  If  you want  to make the squelch value  different  on any
other channel,  then you will have to go to  that channel  and set the
squelch by following the procedure given above.

^rVCO AND REFERENCE OSCILLATOR MODULATION:^r
When adjusting deviation,  two separate adjustments are required - one
for  VCO  modulation  and  the  other  for  the  Reference  Oscillator
Modulation.  The procedure given below  will go through both  of these
adjustments.

* Connect  the RF  BNC connector to  a 50  ohm load  and to  a service
monitor so that you can measure deviation.

* Select  the "VCO  Modulation"  function on the Tune Channel  menu by
using the UP or DOWN arrow key.

* Using the [+] or [-] key, set the VCO modulation value to 1F.

* Select the "Reference Osc.  Modulation" function on the Tune Channel
menu by using the UP or DOWN arrow key.

* Using either the [+] or [-] key,  set the  Reference Osc. Modulation
value to 0F.

* Now select the "VCO Modulation" function on the Tune Channel Menu.

* Apply a 1 kHz, 25 mV RMS tone to the external microphone port on the
test  set.  Measure this  level at  the AC/DC  metering  jacks  on the
Portable Test Set. Measure deviation by keying up the radio.
* De-key the radio and adjust  the VCO modulation  value.  Use the [-]
key to decrease the deviation.

* Re-key  the radio and measure the  deviation.  Repeat  the procedure
(this step and the step  above this)  until the  required deviation is
reached.

* Apply a 355  mV RMS,  1  kHz tone to the to the  auxiliary transmit
port on the radio (the female BNC on the RKT-4203A).  The signal level
should be measured with the audio generator connected to the radio. To
do  this  you  may  have  to  use  a  T-connector  so   that  you  can
simultaneously apply the signal to the radio as well as applying it to
the AC meter.

* Select the "Reference Osc.  Modulation" function on the Tune Channel
menu by using the UP or DOWN arrow key.
* Key the radio.  The auxiliary TX port will become  enabled. Measure
the deviation and note it as DEV 1. De-key the radio.

* Remove  the 1  kHz tone and apply a 335mV RMS,  20  Hz tone to the
auxiliary port.

* Key the radio.  The auxiliary TX port will  become enabled. Measure
the deviation and note it as DEV 2. De-key the radio.

* Adjust the Reference Oscillator modulation value by using the [+] or
[-] keys. Repeat the step above until DEV 2 = DEV 1.

Note: This procedure is required on a per channel basis if the carrier
frequency changes.


Note also  that  you can use the [F9]  key to  copy  the value  of the
selected  data field  to all channels in  the radio.  However you must
still  check the other channels  to  ensure that the deviation  is set
correctly on those other channels.

Once you have completed tuning press the [F10] key to  exit  this menu
or the [ESC] key to jump back to the Main Menu screen.

^rOnce all tuning has been  completed,  you must reprogram  the radio so
that it  will  contain the values  for the  parameters  that  you have
adjusted.^r

                 * * *  END  OF  HELP  TEXT  * * *
