Author Topic: Station licence, output power, where?  (Read 2675 times)

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Offline HS0ZED

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Station licence, output power, where?
« on: November 20, 2009, 02:02:01 PM »
I think most on here will be familiar with the documentation we have to support our activities in particular the equipment licence and the station licence.

Whilst the equipment licence specifies the power of the radio, input power or output power depending on the knowledge of the individual who writes up the licence, I've got some of each! The station licence, for amateur intermediate class licencees specifies 10, 100, or 200 watts. My question for the assembled masses here is very simple. At which point is this station licence power to be measured? Is it:

a. At the back of the radio transmitter unit?
b. After the tuning unit, coupler, filter or other associated device (amplifier?)?
c. At the antenna feed point?
d. The effective radiated power, allowing for gains and losses in the antenna system?

HS0ZIE

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Re: Station licence, output power, where?
« Reply #1 on: November 20, 2009, 05:34:41 PM »
god question I dont think NTC can answer that one

My radio is TS-940 100 watt output but NTC specified it as 200 Watt Because Kenwood say in the Manual 220 W PEP

 ::) ::)

Offline HS0ZIV

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Re: Station licence, output power, where?
« Reply #2 on: November 23, 2009, 09:11:01 AM »
Maybe this link helps you
http://eng.ntc.or.th/index.php?option=com_content&task=view&id=507&Itemid=0
Watch point 20.
20. Notification of the National Telecommunications Commission On Technical Standards for Telecommunication Equipment Re: Radiocommunication Equipment in Amateur Radio Service 

73 Helmut
HS0ZIV

Offline HS0ZJF / ON4AFU / XU7AFU)

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Re: Station licence, output power, where?
« Reply #3 on: December 02, 2009, 04:44:50 PM »
Dear OM,

for as far as I know, and also according to the international conventions ( ITU ) an output power is always measured at the outputplug of the transmitter .
Professional  Power measurements always will be done with a Wattmeter and a DIRECTIONAL Coupler ( pe HP 77D ) in case the measurements are done on an antannesystem where you always will find some SWR . So with the directional coupler you can measure separated the forward and reflected power. In case the measurements are done on a calibrated 50ohm charge only a Wattmeter will be used. The method with 50ohm charge is mostely used ....   

There are execptions for VHF-UHF-SHF installations where sometimes an amplifier is very closed to the antennasystem ( because of losses ) ... Here the power must be measured at the outputconnector of the amplifier.


When we talk about powermeasurements we have:


Outputpower in Watt or dBm ... 100W = 50dBm   measured at the outputplug of the final amplifier.

Inputpower in Watt or dBm .... 100W= 50dBm : measured at the outputplug of the amp but also taken in account the "reflected" power because many build in systems measure both at the same time. So mostely due of some SWR you will measure some more than 100W ( 100W output plus 25W reflected = 125W = 51dBm Input ..... this value you still can find on some older amplifiers as Heatkit SB200 SB220... where they say 1000W INPUT) .

Effectif Injected power EIP .... measured at the "base" of the atennasystem : so taken in account all the losses of the line between transmitter and antenne ( so 100W outputpower = 50dBm    minus 3dB cable, connector and other losses = 47dBm = 50W EIP)

Effectif Radiated Power ERP = outputpower MINUS the line and other losses PLUS the ANTENNAGAIN  ( 100W=50dBm outputpower minus 3dB losses plus 6dB antennagain = 53dBm = 200W ERP) 

I hope I could help you .
Regards   73
Eddy   hs0zjf/on4afu/xu7afu