MATCHING IMPEDANCE

[DIRTY HARRY]

HI FOLKS! PLEASE CAN ANYBODY TELL ME HOW TO RECTIFY THE IMPEDANCE BETWEEN MY FEEDLINE & ANTENNA??, THE FEEDLINE IS 50OHMS & THE ANTENNA 75OHMS. THE ANTENNA IS A 5/8 WAVE VERTICAL WHICH I INTEND TO USE ON 11 METERS & ANY HELP WILL BE APPRECIATED AS TO HELP ME. CHEERS,SHAUN.

 

[Master Chief]

WHAT? I CAN'T HEAR YOU! CAN YOU PLEASE SPEAK UP?!

 

[DIRTY HARRY]

WHAT? I CAN'T HEAR YOU! CAN YOU PLEASE SPEAK UP?!

I ALWAYS WRITE IN LARGE PRINT AS I HAVE DAMAGED EYESIGHT, DUE TO MY TIME IN IRAQ.

 

[Master Chief]

You might have a hard time reading some of the responses then.

 

[Hamin' X]

The mismatch between the antenna and the coax will only result in a 1.6:1 SWR and will not impact the performance of the radio in a significant way.

The big question should be, what kind of antenna are you using on 11 meters, that has a 75 ohm impedance?

Rich

 

[DIRTY HARRY]

You might have a hard time reading some of the responses then.

OBVIOUSLEY I MIGHT HAVE, WHY YOU GOT A PROBLEM WITH IT??? JUST MAKES IT EASIER FOR ME.

 

[DIRTY HARRY]

[quote="Hamin'

The big question should be, what kind of antenna are you using on 11 meters, that has a 75 ohm impedance?

Rich[/size][/quote]
HI HAMIN X, YEP ITS CALLED A PROBE 5800, IT LOOKS SIMILAR TO THE ANTRON 99, EXEPT ITS 21FT LONG & DOES NOT HAVE THE TUNING RINGS LIKE THE ANTRON 99, SHAUN.

 

[bob85]

IF ITS A KESTREL PROBE IT SHOULD HAVE 3 RADIALS AT THE BASE AND SHOULD BE NEARER TO 50 OHMS WHEN MOUNTED IN THE CLEAR

 

[DIRTY HARRY]

IF ITS A KESTREL PROBE IT SHOULD HAVE 3 RADIALS AT THE BASE AND SHOULD BE NEARER TO 50 OHMS

A BIG NEGATIVE ON THAT BOB, ITS JUST CALLED A PROBE 5800. CHEERS ANYWAY.

 

[Butcher318]

Warby, on most any forum when you type in bold it means you are shouting or trying to make a word stand out. THATS WHY HE SAID THAT. See, like that.

You might try posting the question in the ANTENNA SECTION, could get more replys.

 

[DIRTY HARRY]

I KNOW THAT ABOUT TYPING IN LARGE PRINT, JUST FELT HE COULD OF GONE ABOUT ASKING ME WHY I WAS TYPING IN LARGE BEFORE COMMENTING, I POSTED IT ON HERE BECAUSE ANOTHER EARLIER THREAD HAD BEEN PUT ON HERE ABOUT IMPEDANCE, IF ANYBODY FROM ADMIN IS READING THIS PLEASE WILL YOU MOVE THIS TOPIC TO ANTENNA'S FOR ME, CHEERS!!

 

[Paris]

I'm sure Hamin'X has worked the formula right, but I suspect that your SWR will actually be more than 1.6:1. I think this because I had a 10 Ohm mis-match, and the SWR was ~1.6-1.7:1. So, I'm pretty sure that a 25 Ohm mis-match will lead to something worse. How to fix it? How would you fix it on the big radios -- an antenna tuner, I guess. Para Dynamics makes just such a gizmo for CB radios. In fact, I have one; I'll give it a try tomorrow and let you know if it's worth anything.

 

[ken white]

For a mismatch between 75 Ohms and 50 Ohms, the VSWR will be 1.5:1 (75/50) assuming the ohms are purely resistive and not reactive.

 

[DIRTY HARRY]

HI PARIS, WELL A MATCHER WONT SOLVE THE IMPEDANCE DIFFERENCES, IT WILL JUST CREATE A MATCH BETWEEN THE TRANSCEIVER & THE TRANCEIVER END OF THE FEEDLINE (COAX) & NOT BETWEEN THE OTHER END OF THE FEEDLINE & THE ANTENNA WHERE A MIS-MATCH WILL STILL EXIST.I HAVE READ ABOUT BALUNS, & TRANSMISSION LINE TRANFORMERS ETC, BUT IM NOT SURE HOW TO MAKE ONE OR SET ONE UP, HOPE FULY SOMEBODY ON HERE WILL BE ABLE TO HELP ME????

 

[DIRTY HARRY]

For a mismatch between 75 Ohms and 50 Ohms, the VSWR will be 1.5:1 (75/50) assuming the ohms are purely resistive and not reactive.

HI KEN, YEP YOU ARE RIGHT ON THE 1.6:1 SWR, ANY IDEAS HOW I CAN RECTIFY THE DIFFERENCE BUD??