====== SX 600 simple user guide ======

SX 600 is simple non-accurate easy-to-use SWR meter located in brmlab subsection named radiolab. Here easy guide for measuring handheld radio antenna is descibed

===== Official operation instructions ====
{{ :project:ok1rbm:sx600.pdf | official documentation}}

===== basic operation =====

==== prerequisities ====
  * SX-600 SWR meter (see [[http://192.168.77.20/brmsklad/items/|brmsklad]] for location)
  * cables to connect antenna to radio (see [[http://192.168.77.20/brmsklad/items/|brmsklad]] for location)
  * antenna which is measured
  * TX source (your radio, it's preferable to have some which can give decent power to the circuit - 4W is sufficient)

==== experimental setup ====
  * connect radio to SWR Radio channel (for commonly used radio freq sensor 2 TX connector - if unsure, see {{ :project:ok1rbm:sx600.pdf | official documentation}})
  * connect antenna to SWR antenna channel (second plug on same side, in this case sensor 2 ANT connector)
  * if you're measuring just SWR and not forward or reflected pwr, you don't need to connect SWR to external power source

== usefull notes ==
    * for results closer to application situation geometry of experiment simillar to real situation is preffered, if you're measuring antenna for handheld radio, it's good to grab connector near antenna itself to simulate geometry simillar to when you're holding radio and communicate.
  * geometry of experiment can crucially change SWR (for detailed results see [[project:ok1rbm:sx-600#example|example]] below)

==== measurment itself ====
  * set aproppiate power range (for 4W handheld radio 5W is good choice)
  * turn cal knob just to 0 (turn it CCW to minimal position)
  * switch Function switch to CAL position 
  * open channel on radio and turn cal knob to triangle mark (it's on end of the scale, right upper corner)
  * close channel on radio
  * switch Function switch to SWR position
  * open channel on radio and check for SWR value on scale, it's second big red line from top.
  * calibration of scale (that means CAL cycle) is function of frq, that means that instrument needs to be recalibrated on every frequency change to give reliable results.

for deeper insight don't hesitate to see {{ :project:ok1rbm:sx600.pdf | official documentation}} it's pretty short and easily understandable.

 * Measuring forward and reflected power and calculating SWR is more precise, but also more time-demanding.

===== example =====

==== measuring of Nagoya NA-701 from CN distributor ====

antenna was obtained through unverified channel, so it can be clone, but price was pretty friendly. Antenna is marked as 144/430 MHz and it's used mainly on ~173-177 (SD70) and ~466 (PMR) channels, so three wavelenghts were measured and recorded, also shift by geometry of experiment was monitored. Results are collected in Table 1 below.

=== results ===
<table>
<caption>table 1 NA-701 144/430 frequency-SWR values measured by SX-600</caption>
|frq| |SWR {a}|SWR {b}|
| | | | |
|144.000| | almost 10 | around 2-3 |
|177.000| | notably more than 10 {c} |   slightly over 10 {c} |
|446.000| |2                         |   around 1,8 , maybe slightly better |
</table>
notes:

a) antena freely hangs from table

b) cable which was connected to antena was held just under antenna to simulate real world enviroment

c) SWR start's to be pretty unprecise in those values

<table>
<caption>table 2 NA-701 144/430 frequency-Pf,Pr values measured by SX-600</caption>
|frq| | Pforw | Prefl | SWR |
| | | | | |
|172.000| | 2.6 | 0.9  | 12.8{a} |
|172.000| | 4.5 | 3.2  | 11.8{a,b} |
|446.000| | 1.7 | 0.4  | 2.9{a} |
</table>
notes:

a) calculated by equation from documentation SWR = [sqrt(Pf) + sqrt(Pr)]/[sqrt(Pf) - sqrt(Pr)]

b) measured another day, antena hanging freely

==== measuring original baofeng antenna ====

<table>
<caption>table 3 - measuring original baofeng antenna frequency-Pf,Pr values measured by SX-600</caption>
|frq| | Pforw | Prefl | SWR |
| | | | | |
|172.000| | 4.8 | 3  | 8.6{a} |
|446.000| | 3.2 | 0  | 1{a} |
</table>
notes:
a) calculated by equation from documentation SWR = [sqrt(Pf) + sqrt(Pr)]/[sqrt(Pf) - sqrt(Pr)]

==== measuring china NA-771 =====
<table>
<caption>table 3 - measuring china RH771 antenna frequency-Pf,Pr values measured by SX-600</caption>
|frq| | Pforw | Prefl | SWR |
| | | | | |
|172.000| | 3.8 | 2.4  | 8.7{a} |
|446.000| | 2.4 | 1.3  | 6.6{a} |
</table>
notes:
a) calculated by equation from documentation SWR = [sqrt(Pf) + sqrt(Pr)]/[sqrt(Pf) - sqrt(Pr)] , measured "hanging freely"


==== measuring taiwan NA-701 =====
<table>
<caption>table 3 - measuring china NA-771 antenna frequency-Pf,Pr values measured by SX-600</caption>
|frq| | Pforw | Prefl | SWR |
| | | | | |
|172.000| | 4 | 3.5  | 30{a} |
|446.000| | 1.8 | 0.4  | 2.8{a} |
</table>
notes:
a) calculated by equation from documentation SWR = [sqrt(Pf) + sqrt(Pr)]/[sqrt(Pf) - sqrt(Pr)] , measured "hanging freely" - looked same from hand

==== original wouxun antenna =====
<table>
<caption>table 3 - measuring original wouxun antenna frequency-Pf,Pr values measured by SX-600</caption>
|frq| | Pforw | Prefl | SWR |
| | | | | |
|172.000| | 2.6 | 1.1  | 4.72{a} |
|446.000| | 1.9 | 0.9  | 5.4{a} |
</table>
notes:
a) calculated by equation from documentation SWR = [sqrt(Pf) + sqrt(Pr)]/[sqrt(Pf) - sqrt(Pr)] , measured "hanging from hand"