开云体育

1/2 coax wavelength

#nanovna-h4

James Balagtas All Messages By This Member #23344 Hi guys Wonder if you can acctually cut an exact 1/2 wave coax for a given freq without getting VF and math usong nano VNA. It woukd be very useful when making 4:1 balun with better accuracy rather than estimating with math. I also need it for duplexer pigtails. Ive been searching in youtube if soneone ever did a video. Thanks more power DW3JBX James
Clyde Spencer All Messages By This Member #23346 You can try this process. [image: image.png] Clyde K. Spencer toggle quoted message Show quoted text On Fri, Jul 16, 2021 at 4:15 AM James Balagtas <jbx907@...> wrote: Hi guys Wonder if you can acctually cut an exact 1/2 wave coax for a given freq without getting VF and math usong nano VNA. It woukd be very useful when making 4:1 balun with better accuracy rather than estimating with math. I also need it for duplexer pigtails. Ive been searching in youtube if soneone ever did a video. Thanks more power DW3JBX James image.png
Clyde Spencer All Messages By This Member #23347 Forgot one important note. Trim the coax stub until the dip is at the desired frequency. Clyde K. Spencer toggle quoted message Show quoted text On Fri, Jul 16, 2021 at 7:55 AM Clyde Spencer <cftr01b@...> wrote: You can try this process. [image: image.png] Clyde K. Spencer On Fri, Jul 16, 2021 at 4:15 AM James Balagtas <jbx907@...> wrote: Hi guys Wonder if you can acctually cut an exact 1/2 wave coax for a given freq without getting VF and math usong nano VNA. It woukd be very useful when making 4:1 balun with better accuracy rather than estimating with math. I also need it for duplexer pigtails. Ive been searching in youtube if soneone ever did a video. Thanks more power DW3JBX James image.png
Jim Lux All Messages By This Member #23348 On 7/16/21 12:16 AM, James Balagtas wrote: Hi guys Wonder if you can acctually cut an exact 1/2 wave coax for a given freq without getting VF and math usong nano VNA. It woukd be very useful when making 4:1 balun with better accuracy rather than estimating with math. Very easy - cal the vna, hook up your coax, look at the phase of S11.? Cut until the phase is zero degrees at your frequency of interest.? Your cable is a multiple of half wavelengths. 180 degrees phase shift on the way out, reflection from the open (which does not flip the phase, like a short does), 180 degree phase shift on the way back, so the net is zero degrees. The magnitude of S11 is twice the cable loss. If you want a 1/4 wave stub, go for 180 degrees. 90 degrees on the way out, reflect, 90 degrees on the way back. I also need it for duplexer pigtails. Ive been searching in youtube if soneone ever did a video. Thanks more power DW3JBX James
Fred KB4QZH All Messages By This Member #23349 Look at W2AEW YouTube channel I think he did a video on this. 73 Fred KB4QZH
n5kzw All Messages By This Member #23366 When you go to put a connector on the open end, make sure the center conductor of the cable is flush with the end of the center contact on the connector. Trim the outer cover, shield, and dielectric as needed. Then double check with the VNA. Ed

Previous Topic Next Topic