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if the smart folk are correct there is no sense in saying a choke can't hurt in any situation,
unlucky coax outer shield length + unlucky choke ={Cry_river}

we know the only thing that determines vswr is the load impedance in relation to the coax characteristic impedance ( look it up and or do tests don't blindly believe what you read on forums including what i post )

ignoring the unlucky choke/coax length scenario, adding a choke can still change the match,

common mode impedance is seen in parallel with the antenna load impedance,
if altering coax length alters your vswr more than what can be attributed to any change in coax loss due to the different length coax you very likely have cm currents on the coax outer shield and a common mode impedance seen in parallel with the load that changes with coax length and it been grounded or not grounded,

inserting a high series impedance in the coax outer shield by winding a choke or adding ferrite can raise the parallel common mode impedance to reduce the cm currents which will change the effective load impedance in the same way that changing coax length or grounding/ungrounding your coax can change the common mode impedance/current = changes load impedance = changes vswr.

<blockquote data-quote="bob85" data-source="post: 427315" data-attributes="member: 18">if the smart folk are correct there is no sense in saying a choke can&#039;t hurt in any situation, unlucky coax outer shield length + unlucky choke ={Cry_river}we know the only thing that determines vswr is the load impedance in relation to the coax characteristic impedance ( look it up and or do tests don&#039;t blindly believe what you read on forums including what i post )ignoring the unlucky choke/coax length scenario, adding a choke can still change the match,common mode impedance is seen in parallel with the antenna load impedance,if altering coax length alters your vswr more than what can be attributed to any change in coax loss due to the different length coax you very likely have cm currents on the coax outer shield and a common mode impedance seen in parallel with the load that changes with coax length and it been grounded or not grounded,inserting a high series impedance in the coax outer shield by winding a choke or adding ferrite can raise the parallel common mode impedance to reduce the cm currents which will change the effective load impedance in the same way that changing coax length or grounding/ungrounding your coax can change the common mode impedance/current = changes load impedance = changes vswr.</blockquote>

[QUOTE="bob85, post: 427315, member: 18"] if the smart folk are correct there is no sense in saying a choke can't hurt in any situation, unlucky coax outer shield length + unlucky choke ={Cry_river} we know the only thing that determines vswr is the load impedance in relation to the coax characteristic impedance ( look it up and or do tests don't blindly believe what you read on forums including what i post ) ignoring the unlucky choke/coax length scenario, adding a choke can still change the match, common mode impedance is seen in parallel with the antenna load impedance, if altering coax length alters your vswr more than what can be attributed to any change in coax loss due to the different length coax you very likely have cm currents on the coax outer shield and a common mode impedance seen in parallel with the load that changes with coax length and it been grounded or not grounded, inserting a high series impedance in the coax outer shield by winding a choke or adding ferrite can raise the parallel common mode impedance to reduce the cm currents which will change the effective load impedance in the same way that changing coax length or grounding/ungrounding your coax can change the common mode impedance/current = changes load impedance = changes vswr. [/QUOTE]

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