Hello Duane: To my knowledge, the following are the reference impedance's called out in the following documents for the UK:
NET 4 (ETS 300 001): Just like you said, 370 ohms + 620 ohm//310nF NTR3: 270 ohms + 750 ohms//150nF BS6305 (class a equipment): 370 ohms + 620 ohms//310nF TBR21: 270 ohms + 750 ohms//150nF Joe referenced BABT SITS 94/54 in his article as being 275 ohms + 780ohms//150nF. This has now become NTR3 (you will notice there is a slight difference in the reference termination's of NTR3 and BABT SITS 94/54). The Reference Termination in NET4 mirrors that of BS6305. Right now, there are three approval options for the UK. Approval to BS6305 (i think it is finally on its last dying gasp), NTR3, or NET4. NTR3 closely follows TBR21. I would recommend referring to BABT Application Note number 56. In short, I believe that the 275 ohms + 780ohms//150nF is obsolete (along with BABT SITS 94/54), and has been replaced by 270 ohms + 750 ohms//150nF (NTR3). The BS6305/NET4 option (370 ohms + 620ohms//310nF) is also a valid option. Is this correct Joe? All known disclaimers apply. Mel Pedersen, Homologations Engineer Midcom, Inc. e-mail: [email protected] Phone: (605) 882-8535 Fax: (605) 886-6752 ---------- From: Duane J Marcroft[SMTP:[email protected]] Sent: Monday, February 17, 1997 2:28 PM To: [email protected] Cc: [email protected] Subject: U.K. Complex Impedance Network for Measuring Return Loss Joe, I read your article on U.K. Requirements in the Compliance Engineering 1996 Reference Guide. The article indicates the RT reference network is a 275 ohm resistor in series with a parallel network consisting of a 780 ohm resistor and 310 nF capacitor. A different network is shown in ETS 300 001:March 1996, Chapter 4 [4.1.2 (GB) 1]. It shows a 370 ohm resistor in series with a parallel network consisting of a 620 ohm resistor and 310 nF capacitor. Do you or any other TREG'R know which is correct? Thank you in advance. Regards, Duane
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