[TowerTalk] 4 SQ issue

[Lux, Jim]

On 11/2/21 3:01 PM, Lux, Jim wrote:
> On 11/2/21 11:41 AM, Mpridesti via TowerTalk wrote:
>> My 80 m 4 SQ seems to work well in 3 positions. To the SW the signal 
>> drop in the favored direction where the other 3 directions appear to 
>> work well.
>>
>> SWR measurements seem normal around 2:1 at the end of the 1/4 wave 75 
>> ohm lines except one which is 1.87. Haven’t made loss measurements 
>> yet but I suspect the lowest SWR line is the problem (low reading due 
>> to higher than normal loss making it the suspect line).
>>
>> Has anyone else experienced this type of behavior?  Also the suspect 
>> line is the NW element and the direction which has the problem is SW. 
>> Does this make sense? Effectively this lossy element is the other 
>> half of the “driven element “ if you thought of the 4 sq as a 3 el 
>> vertical beam.
>>
>> Keeping with this concept, one would think the NE direction would 
>> have similar loss but it doesn’t (or it’s not noticeable).
>
>
> This is where a NanoVNA might be a useful tool.  Not only can you go 
> out to the box and measure each element separately, but you could 
> measure the element to element coupling, and I'll bet you'd see 
> something.
>
> You *might* be able to do a sweep from the shack, through the box, and 
> figure something out too, but figuring out which of the 4 has a 
> problem - I guess you could switch the direction of the beam and 
> probably figure it out.


FWIW TDR (from a sweep) would definitely show a lossy cable or element.