Using the SA 7L13 and the TR502 to calibrate a filter with 75 ohm impedance.


Attilio
 

Hello everybody,
I would like to calibrate a VHF band pass filter using the tracking generator TR503 (converted to TR502) and the SA 7L13 in the mainframe 7613, but I have the problem that they have a characteristic impedance of 50 ohm while the filter has input and output impedance of 75 ohm . How can I do ?
I have seen on the internet a 50 to 75 ohm BNC adapter (5.7 dB attenuation) but it is quite expensive.

Thanks for the attention
-- Cheers
Attilio


EB4APL
 

You can build it at home, it is just a 2 resistor pad. Google for minimum loss adapter.

Regards,

Ignacio EB4APL

El 12/03/2021 a las 16:09, Attilio escribió:
Hello everybody,
I would like to calibrate a VHF band pass filter using the tracking generator TR503 (converted to TR502) and the SA 7L13 in the mainframe 7613, but I have the problem that they have a characteristic impedance of 50 ohm while the filter has input and output impedance of 75 ohm . How can I do ?
I have seen on the internet a 50 to 75 ohm BNC adapter (5.7 dB attenuation) but it is quite expensive.

Thanks for the attention
-- Cheers
Attilio
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On Fri, Mar 12, 2021 at 05:08 PM, EB4APL wrote:


You can build it at home, it is just a 2 resistor pad. Google for minimum loss
adapter.
The following will do fine: At the 50 Ohm side: 91 Ohm to Gnd. 43 Ohm between 50 Ohm and 75 Ohm signal lines.

Raymond


Attilio
 

Thanks great advice,
I put everything in a small metal box with two BNC connectors (input / output). On the 75 ohm side I put a 75 ohm BNC connector.