antentopSince2 July

** PLEASE DESCRIBE THIS IMAGE **
** PLEASE DESCRIBE THIS IMAGE **

 

 

 

 

Antentop is FREE e-magazine devoted to Antennas and Amateur Radio an

Special page devoted to

Two Simple Low Pass Filters for 145 - MHz Band

Custom Search

 

ANTENTOP- 01- 2018 # 022

Two Simple Low Pass Filters for 145- MHz Band

 

 

Figure 11 Layout of the PCB capacitors

 

Inductor 106 nano- H contains 4 turns. ID is 10 mm. Inductor is wound by wire in diameter of 1.5- mm (14 AWG), 5- mm gap between turns.

Inductor 62 nano-H contains 2 turns. ID is 10 mm. Inductor is wound by wire in diameter of 1.5- mm (14 AWG), 5- mm gap between turns.

 

Filter has SWR 1.1:1 at the 2- meter band. Figure 12 shows SWR for the filter at the 2- meter Band. Figure 13 shows return loss of the Low Pass Filter for 145- MHz Band at frequencies 200- 500- MHz. Figure 14 shows attenuation for the Low Pass Filter for 145- MHz Band at the 2- meter Band.

Best result for tuning the filter will provide a Spectrum Analyzer. In this case the tuning may take just 20 minutes. At first step the filter is tuned for low SWR. At this step inductors are adjusted by pressing/ stretching. At the second step the filter is reversed (where was the filter's input- now is the filter's output) and the filter checked and adjusted if it is needed. The filter may be tuned without a Spectrum Analyzer. Just turn on the filter to a transmitter, load the filter to 50- Ohm, and tune the inductors to minima SWR. The procedure may be done with the real antenna system (cable plus antenna).

73! RL1L

 

 

 

 

Figure 12 SWR for the Low Pass Filter for 145- MHz Band at the 2- meter Band

 

 

www.antentop.org

Page- 78

 

74 75 76 77 78 79


 

 

Just for Fun:

Map IP Address
Powered byIP2Location.com

Thanks for your time!

Last Updated:

January 3, 2020 21:10

** PLEASE DESCRIBE THIS IMAGE **

** PLEASE DESCRIBE THIS IMAGE **

2003entop